DEDICATION

Thissymposium is dedicated to thememory of Dr. Mike S. Laverack, Pioneerin thestudy of sensorystructures in Crustaceans.

Henever lost sight of the fact that the Class Crustacea includes many interesting animalsbesides lobsters, crayfish and crabs.

Dr.Laverack was involved in the initial stages ofthe planning ofthe symposium. Manyof his ideas for topicsand participants have been incorporated into the symposium plans. ACKNOWLEDGEMENTS

Thesymposium started as a vagueidea and a sensethat most sensory biology meetings lackpapers on zooplankton, and most zooplankton behavior conferences have few if any papersfocused on sensoryaspects. From these beginnings, many people have helped us in theevolution from idea to symposium.We would like to thankDr. RandyAlberte, Officeof NavalResearch, Dr. Jack Davidson, University of Hawai'iSea Grant College Program,Dr. FredGreenwood, Director of PacificBiomedical Research Center, Dr. MikeLaverack, Dr. DavidMacmillan, University of Melbourne,Dr. GusPaffenhofer, SkidawayInstitute of Oceanography,Dr.Art Popper,University of Maryland,College Park,Prof. Dr. PiergiorgioStrata, International Brain Research Organization, and Prof. Dr. Konrad Wiese,Universitat Hamburg.

Thissymposium would not have been possible without generous support from the Office of NavalResearch, International Brain Research Organization, Pacific Biomedical ResearchCenter Universityof Hawai'iat Manoa!,University of Hawai'iSea Grant CollegeProgram, and University of MarylandSystem Center for Environmentaland EstuarineStudies, Horn Point Environmental Laboratory!. The special luncheon with a keynoteaddress by Dr. TheodoreBullock is partiallysupported by the Hawaii State Chapterof the Societyfor Neuroscience.

Thestaff at PacificBiomedical Research Center, University of Hawaiigenerously supportedthe symposium through their time, advice and secretarial expertise. We would speciallylike to thankMr. Dave Au, Administrative Officer, Dr, Marilyn Dunlap, BiologicalElectron Microscope Facility, Dr. Brad Jones, Bekesy Lab. of Neurobiology, Ms.Carol Kosaki, Bekesy Lab. of Neurobiologyand Ms. Lynette Reyes, Bekesy Lab. of Neurobiology. Wewould like to thankMs. Yvonne Yamashita, UH Conference Center, College of ContinuingEducation and Community Service, who provided much needed logistical support.We also thank the staff of theAla MoanaHotel for theirefficient and helpful support with the conference details. SYMPOSIUM PROGRAM SUNDAY,JANUARY 8, 1995:REGISTRATION AND RECEPTION

1800-2000 Registration outside GardenLanai

1800 No-hostcocktail reception Garden Lanai

1830 Welcome P. Lenz Symposium Goals D. Hartline Introductions J. Purcell

MONDAY, JANUARY 9, 1995: GENERAL

MORNING SESSION Garden Lanai

0825 Introduction Chair; K. Wiese

SENSORY SYSTEMS

0830 J. Atema Spectral,temporal and spatial signals in nearfieldand farfield chemoreception

0900 D. Mellon,Jr. Characteristicsof broadspectrum neurons in crustacean olfactory midbrain

0920 T. Cronin,N.J. Marshall and R.L. Caldwell Compound eyes and photoreceptionin meroplanktoniccrustacean larvae

0950 Break GardenLanai coffee,tea, breads!

1010 A.N. Popper Sounddetection by fishes

1040 H. Bleckmann,J. Mogdans and A. Fleck-- Integrationof hydrodynamic information in the hindbrain of fishes

1100 B. Schmitz Reception andproduction ofhydrodynamic stimuli in crayfishand snappingshrimp

PELAGICENVIRONMENT - Physicalaspects

1120 M.A.R.Koehl Hydrodynamicsof olfactory antennae

1140 T. Breithaupt The structureand biological significance of water currents in predator-prey interactionsand chemical communication

1200 Lunch -- Hibiscus Room AFTERNOON SESSION -- Garden Lanai

1300 Introduction Chair: D. Nilsson

PELAGIC ENVIRONMENT - Biologicalaspects

1305 Video presentation: J.R. Strickler Information, information, information! Seeingvon Uexkull's "Umwelt" of planktonic crustaceansand the animal's reactions towards it

1335 D.E. Morse and A.N.C. Morse Signals, receptors,transducers and genes controlling substratum-specificmetamorphosis: Larval ecology and practical applications

CRUSTACEAN MICRONEKTON

1405 J.F. Case No place to hide: Bio]uminescenceand the sensoryecology of pelagic crustaceans

1435 M.I. Latz Cryptic bioluminescence in the midwater environment

1455 M. Omori, H. Fukami and M.I. Latz Confirmation and measurement of bioluminescenceof the pelagic shrimp Sergia lucens

1515 T.M. Frank and E.A. Widder Behavioral sensitivity to near-UV and blue-green light in deep-seacrustaceans

1535 K. Wiese Recording andanalysis of the turbulentpropulsion jet of euphasiid shrimp Crustacea!

1555 Break GardenLanai coffee, tea!

ROTIFERS

1610 P.L. Starkweather Sensory potential in ciliated zooplankton: Structural and behavioral aspectsof diet selectionin rotifers

1635 T.W. Snell and R. Rico-Martinez -- Surfaceglycoproteins serve as contact mate recognition pheromonesin rotifers

1655 D.J. Lonsdale,T.W. Snelland M.Frey Lectin bindingto surfaceglycoproteins on Coullanaspp. Copepoda:Harpacticoida! can inhibit mateguarding TUESDAY,JANUARY 10, 1995:PLANKTONIC CRUSTACEANS

MORNINGSESSION -- GardenLanai

0825 Introduction - Chair: P. Starkweather

0830 P. Larsson Behaviourand ecology of cladocerawith focuson theinfluence of chemical signals in their environment

0900 J. Ringelbergand E. vanGool Memoryfor fish kairomone in Daphnia & E. van Gool andJ. Ringelberg-- The influenceof kairomonesand food concentrationon theresponse of Daphniato changinglight intensities

0930 L. DeMeester Qualitatively different responses of Daphnia clones to the presenceof predator smell

0950 S.I. Dodson Optimal swimming behavior in zooplankton

1010 Break-- GardenLanai coffee,tea, pastries!

1030 D.-E.Nilsson Eye design,vision and invisibility in planktonicinvertebrates 1100 N.J.Marshall and M.F. Land Orientationand tracking by hyperiid amphipods 1120 E.J.Buskey, J.O. Peterson, J.W. Ambler The role of photoreceptionin the swarmingbehavior of the copepodDioithona oculata

1140 J.W.Ambler, S.A. Broadwater, E.J. Buskey, M. Kracht,and J.O. Peterson Mating behavior in swarmsof Dioi bona oculata

1200 Open discussion

1205 Lunch -- Hibiscus Room

1300 SPECIAL LUNCHEON ADDRESS T.H. Bullock,Scripps Institution of Oceanography Neuroethologyand the aquaticrealm

AFTERNOON SESSION GardenLanai

1355 Introduction Chair: J. Case

1400 J. Yen,S. Colin,M. Doall,P. Moore,A. Okuboand J.R. Strickler Mate trackingin copepods:Pheromones or species-specific wakes? 1420 S.M.Bollens, B.W. Frost, and J.R. Cordell Individual behavioral flexibility of themarine copepod Acartia hudsonica in response tofood and predators 1440 G.A. Boxshall, R. Huys, S. Ohtsuka,J.R. Strickler, and J. Yen The evolution of non-feedingmales in marine planktonic copepods

1500 M.H. Bundy and G.-A. Paffenhofer The sensoryphysiology of copepod nauplii investigatedusing laser scanning confocal microscopy

1520 D.K. Hartline and P.H. Lenz Sensory physiological studiesof the first antenna of calanoid copepods

1540 Open discussion

1545 Break Carnation Rooin

1600-2130 Informal video presentations by sign-up! Carnation Room

1600-1700 POSTER PRESENTATIONS I postersgo up by 0830; come down by 2200! Carnation Room la. K.B. Heidelberg, K.P. Sebensand J.E. Purcell Water flow effects on zooplanktonescape behaviors from coral predators lb. L.J. Hansson Behavioural responsesto contactbetween the scyphozoan predator Cyaneacapillata and the prey Aurelia aurita

2a. M. Brewer Virtual plankton: A novel methodfor investigatingzooplankton predator-preyinteractions

2b. J. Gokcenand D. McNaught Behavioral bioassaysemploying Daphnia for detectionof sublethaleffects: responsesto polarizedlight

3a. N. Butler Effects of sedimentloading on food perceptionand ingestionby freshwater zooplankton

3b. C.K. Wong, Q.C. Chen and L.M. Huang -- Responsesof copepodsto hydromechanical stimuli WEDNESDAY,JANUARY 11, 1995: LARVAE

Moaxia4 SvSsroN-- GardenI.anai

0825 Introduction Chair: M. Koehl

MEROP LAN KTON

0830 M. Hadfield Metamorphosis in marine invertebrates: Theneed for speed 0900 R.B. Forward, Jr. -- Sensoryphysiology andbehavior of crab larvae during horizontal transport

0930 M.S.Laverack, D.L. Macmillan and S.L. Sandow -- Neuraldevelopment in theplanktonic and early benthic stages of thepalinurid lobster, Jasus edwardsii 1000 Break GardenLanai coffee,tea, pastries!

1020 A.N.C. Morseand P.T. Raimondi-- Theuse of a novelchemo-inductive substrateresolves factors involved in recruitmentof coral larvae 1040 R.K.Zimmer-Faust Chemosensory ecologyof marine larvae: Benthic-pelagic coupling

MICRONEKTON

1110 B.U.Budelmann Cephalopod sensory neurobiology

1140 Open discussion

1200 Lunch -- Ilima Room

AFTERNOON SESSION Garden Lanai

1310 Introduction Chair: B. Budelmann!

1315 H.I. Browman Sensitive periods in theneurobiological andbehavioral development of fishes

1350 D. Featherstone,C. Drewes and J. Coats A techniquefor noninvasive detectionofneural and muscular electrical events during the escape response in larval fish

1410 F.A.McAlary, E.R. Loew and W.N. McFarland Planktivory in larval fishes: Enhancementof foraging on zooplankton by ultraviolet sensitive vision

1430 Open discussion 1440 Break Carnation Room

1440-2130 Informal video presentations by sign-up! -- CarnationRoom 1530: Doall 1600: Fields 1630: Stewart

1440-1640 POSTER PRESENTATIONSII postersgo up by 0830; come down by 2200! Carnation Room

1440-1540 Poster presentations lla la. M.H. Doall, J. Yen and J.R. Strickler Prey detectionand attack performance in Euchaetarimana, a predatory calanoidcopepod video 1530!

2a. D.M. Fields and J. Yen -- The escape behavior of marine copepods in response to quantifiable fluid disturbance video 1600!

3a. L. Farley, T. Breithauptand J. Atema A comparisonof developmental changesin sensoryanatomy and flow field dynamicsbetween larvae and post-larvae of Homarus americanus

4a. I. Walter and K. Anger Delay of metamorphosisin decapodlarvae due to substrate and conspecific cues sa. T.P. Norekian Sensory inputs to the neuronsunderlying prey capture in the pteropod mollusc, Clione limacina

1540-1640 Posterpresentations lib

lb. E. van Gool and J. Ringelberg The influence of kairomonesand food concentrationon the responseof Daphnia to changinglight intensities

2b. C. Herren, P.H. Lenz and D.K. Hartline -- Behavioralresponses of calanoid copepodsto quantitativemechanical stimuli

3b. T. Weatherbyand P.H. Lenz Morphological studiesof mechano-and chemoreceptivesetae in the first antennaof a calanoidcopepod

4b. S. Stewart Field and laboratory observations of the cubozoan Tripedalia cystophora: implications regarding vision video 1630!

5b. J. Arnold Title not available cephalopod stereocilia!

1930 2030 SPONSORS HOUR Office of Naval Research Dr. Harold Bright Sea Grant Dr. Jack Davidson THURSDAY,JANUARY 12, 1995: GELATINOUS ZOOPLANKTON

MORNINGSESSION Garden Lanai

0825 Introduction Chair: J. Purcell

CNIDARIANS & CTENOPHORES 0830 G.O.Mackie Involution, intimidation, escape: Defensive strategies in planktonic coelenterates

0900 W.M. Hamner Migrationand spawning in cnidarians 0930 J.H.Costello, B.K. Sullivan and C.L. Suchman Prey responses to scyphomedusanflowfields do theyexplain prey selection? 0950 A.N.Spencer, N. Grigoriev and J. Przysiezniak Excitability properties of epitheliaand neurons in Polyorchis Hydrozoa!: Their relevance to behavior 1010 Break -- GardenLanai coffee,tea, pastries! 1030 G. Matsumoto-- Observations onthe anatomy and behaviour of thecubozoan Cary bdea rasronii

1050 J.E.Purcell and P.A.V. Anderson Chemical basis for prey selection in a pelagic cnidarian

1110 T. FalkenhaugandO.B. Stabell Predator-prey interactions in ctenophores 1130 W.Greve Response patterns ofa ctenophore:Pleurobrachia pileus

1150 Open discussion

1200 Lunch, Hibiscus Room

AVfERNOONSESSION Garden Lanai

1310 Introduction Chair: J. Purcell

CHORDATES 1330 L.P.Madin Sensory ecology ofpelagic tunicates: More questions than answers

1400 G.O.Mackie Unconventional signalling mechanisms inpelagic tunicates

10 1430 J.-L. Acuna, D. Deibel and C.C. Morris Flow fields within the pharynx of an oikopleurid tunicate

1450 A.B. Bochdanskyand D. Deibel Behavioral ecologyof Oikopleuravanhoeffeni Appendicularia!

1510 C. Gait -- Larvaceanhouses deter predationby fish and chaetognaths

PTEROPODS

1530 R.A. Satterlie, M. Lagro, M. Titus, S. Jordan and K. Robertson Morphologyof wing mechano-receptorsinvolved in the wing retractionreflex of the pteropod mollusc Clione limacina

1550 Open discussion

1600 TEA PARTY -- Garden Lanai

11 ABSTRACTS FLOWFIELDS WITHIN THE PHAR YNX OF AN OIKOPLEURIDTUNICATE. J.-L.Acuna, D. Deibeland C.C. Morris, 'Departmento deBOS., University Oviedo, c/Jesus Arias de Velasco S/N!, Oviedo 33005, Spain, and Ocean Sciences Centre, Memorial Universityof Newfoundland,Canada Wehave used video-assisted microscopy totrack marker particles within the pharynx of Oikopleuravanhoeffeni. Ourprime motivation wasan attempt torationalize twoapparently contradictoryresults we have published, ! that the pharyngeal filterof O.vanhoegeni is relativelycoarse mean pore dimensions of 3.2 x 6.4Iim! and ! thatthis filter appears to capturesubmicron particles with much higher efficiencies thancan be accounted forby a sieving model. Flowvelocity was highly variable across thesurface ofthe filter, with maximum particle impactvelocities justabove the ciliated spiracles. The mean impact velocity ofparticles we measuredwas 560+290 pm s ' +SD,n =30!.Thus, the Re number is6 x10 fora filterfiber 203nm in diameter. The pharyngeal filteris made ofrectilinear pores and operates ina closed system.Thus, it is an ideal case for application ofthe pressure drop and retention efficiency equationsof Silvester 983! derived from aerosol filtration theory. We used the pore dimensionsandfiber diameter above, and the impact velocities wehave measured, topredict retentionefficiencies using Silvester's equation. Predicted values fall within the 95% confidence limitsof empirically-determinedretentionfor particles between 0.17 and 3 pmin diameter. Thus,direct interception accounts forthe observed overcapture ofvery small particles lessthan the sieve dimensions. MATINGBEHA VIOR IN SWARMSOF DIOITHONAOCULATA. J.W. Ambler, S.A.Broadwater', E.J.Buskey, M.Kracht', and J.O. Peterson, Millersville University, Millersville,PA17551, USA'. Marine Science Institute, University ofTexas atAustin, Port Aransas,TX 78373, USA Theadaptive significance ofdioithonan swarming maybe to enhance mating behavior bybringing together many conspecific adults. Although lightis the primary cue for initiating andmaintaining swarms, chemical cues such as sex phermones mayhelp maintain individuals in a swarm.We observed mating behavior of copepod pairs, and videotaped mating in laboratoryswarms. Laboratory swarms ofsingle stages andsexes were videotaped todetermine if swarmformation andmaintenance depended onthe presence ofadult females which are most photosensitive.Groupscomposed ofonly adult females, adult males, orcopepodid stage5 formeddense swarms, butyounger copepodid stagesdid not. To observe conditions leading to matinginteractions, wefirst created anall male swarm, added experimental animals adult females,virgin females, C5, or males!toa screenedcompartment, andthen raised the screen sothat both groups formed a swarm. Inall these experiments, matingwas observed only betweennewly molted virgin females and males. Motion analysis didnot reveal differences in averageswimming behavior between theinitial swarm with only males, and the later swarm withmales and females mating. Therefore, premating swimming behavior didnot appear tobe differentfrom swimming behavior in swarms. Swimming patterns of coupled pairs was distinctlydifferent, and are heing quantified.

12 SPECTRAL, TEMPORAL AND SPATIAL SIGNALS IN NEARFIELD AND FARFIELD CHEMORECEPTION. J. Atema, Marine Biological Laboratory, Boston University Marine Program, Woods, Hole, MA 02543, USA

For many animals, the world of immediateinterest is only a few body lengths in size. Larger and fasteranimals have greater need for distanceperception. Tactile, hydrodynamicand acoustic pressure signals represent a series of mechanical information channels covering increasingdistances, Specific receptororgans cover the threedistance ranges. A similar series exists in chemoreception. The ranges contact, nearfield, farfield are coveredby a variety of receptor organs, such as taste and smell. All chemicalsignals have in commonthe potential for preciseidentity information. This can include recognition of individuals and their internal stateas well as subtly different food sourcesand homeareas. Thus, spectralsignal analysisis commonto all chemoreceptororgans. In contactand nearfield chemoreception,temporal stimulusanalysis is simple, but here spatial analysisacross the body surfacecan be complex. In farfield chemoreceptionthere is no brain body projection, but here temporalanalysis of turbulently dispersedodor patchesmay be used to locate distant odor sources. Finally, functional and anatomicallinks betweenchemo- and mechanoreceptionare evident but poorly understood.

INTEGRATION OF H YDROD YNAMIC INFORMATION IN THE HINDBRAIN OF FISHES. H. Bleckmann, J. Mogdans and A. Fleck, ZoologischesInstitut der Universitat Bonn, PoppelsdorferSchloP, 53115 Bonn, Germany

Aquatic animalswhich move or which move body parts generatehydrodynamic stimuli which can have frequencycomponents up to 100 Hz or more. Although hydrodynamicstimuli near-fieldwater displacements! attenuate rapidly during stimulus propagation due to thephysical propertiesof water, theyare of greatinterest to both, predatorsand prey. Fish usea special sensory system, the lateral line to detect weak water movements. The lateral line consists of up to several thousandindividual neuromastsspread over the head and body. Lateral line neuromastsare mechanicallow-pass filters which respond about proportional to either the velocity or the accelerationcomponent of a wavestimulus. This holdstrue for frequenciesfrom below 1 Hz up to about 150Hz, i.e. up to the upperfrequency limit of this sensorysystem. Within this frequencyrange, the stimulus parameters duration, amplitude, frequency, and phase are signalledto the brain. Here, we presentdata from electrophysiologicalrecordings in the hindbrainof two fish species,a catfish,Ancistrus sp. andthe goldfish, Carassius auratus. Our datademonstrate in whichway differentaspects of thehydrodynamic stimuli areprocessed by the hindbrain of fishes.

13 BEHAVIORAL ECOLOGY OF OIKOPLEURA VANHOEFFENI APPENDICULARIA!. A.B.Bochdansky andD. Deibel,Ocean Sciences Centre, Memorial University of Newfoundland,St.John' s, Newfoundland,A1C 5S7, Canada A newflow-through technique enabled usto measure theclearance rates and record the behaviorof individual appendicularians simultaneously onvideo. Our direct measurements of theclearance rates support the Morris A. Deibel model 993! which was based onbehavioral andmorphological studies on this species. Detailed time-budget analysis of the major componentsof the behavior time spent feeding [TSF], tailbeat frequency [TBF] and the presenceorabsence of the pharyngeal filter!, revealed that the 'feeding effort' is best described by theproduct of TSFand TBF. O. vanhoeffeniactively responded to an increased food concentrationby reducing their feeding effort down to a certainthreshold level. Further increaseoffood concentration resultedin a linearincrease ofthe ingestion rates determined by fecalpellet volume! with food concentration. In ourexperiments TSFvaried by 10-fold 0-100%!,whereas theTBF was bracketed within 0.6 to 1.3 tailbeats persecond -4 degrees C!.More variance inthe clearance rateswas explained byTSF than by size for animals varying from2.16 to 5.6 mm in trunk length. Time intervals between fecal pellets was independent of thefood concentration, suggesting constant gut passage times. However, the time interval betweentheegestion offecal pellets changed dramatically whenthe animals ceased toproduce thepharyngeal filter. Theimplications of our findings for particle fluxes in thesea and for the designof functionalresponse experiments will bediscussed.

INDIVIDUALBEHAVIORAL FLEXIBILITY OF THEMARINE COPEPOD ACARTlA HUDSONICAINRESPONSE TOFOOD AND PREDATORS. S.M.Bollens, B.W. Frost, andJ.R. Cordell, 'Biology Departinent, WoodsHole Oceanographic Institute,Woods Hole, MA,02543 zSchool ofOceanography, WB-10,University ofWashington, Seattle,WA 98195, ~FisheriesResearch Institute, WH-10, University ofWashington, Seattle,WA 98195, USA Wepresent results from a suiteof experimentalstudies investigating if individual A. hudsonicapossess flexibility in theirhabitat depth! selection behavior. A seriesof manipulationexperiments wereundertaken ina temperate marine lagoon inwhich we varied the concentrationofboth predators andfood resources inwell-replicated, insitu plastic enclosures spanningthenatural depth range ofthe copepods. Wereview briefly some ofour previously publishedresults indicating that adult female A. hudsonicacanrespond to the presence or absenceoftheir natural predator, thethreespine stickleback Gasterosteus aculealus!, byaltering theirdiel vertical migration behavior andtheir diel cycle offeeding. More recent, unpublished resultsare presented indicating that A. hudsonicacan also alter their vertical distribution in responseto variable food resources. These results are discussed in the context of individual zooplanktersmaking trade-offs between predator avoidance andfeeding intheir habitat selection behavior.

14 THE EVOLUTION OF NON-FEEDING MALES IN MARINE PLANKTONIC COPEPODS. G.A. Boxshall, R. Huys, S. Ohtsuka, J.R. Strickler, and J. Yen, The NaturalHistory Museum, London SW7 5BD, London, U.K. FisheriesLaboratory, Hiroshima University, 1294Takehara-cho, Hiroshima 725, Japan. ~Centerfor GreatLakes Research, University Wisconsin-Milwaukee,600 E. GreenfieldAve., Milwaukee,WI 53204, USA. Marine SciencesResearch Center, State University of New York, StonyBrook, NY 11974- 5000, USA

Non-feedingadult maleswith atrophiedmouthparts are morewidespread amongst the marineplanktonic copepods than hithertorealised. Phylogeneticanalysis indicates that this phenomenonhas evolved independently on numerousoccasions and examples can be foundin five different orders: Calanoida,Harpacticoida, Poecilostomatoida, Siphonostomatoida and Mormonilloida. The extentof the degenerationin mouthpartstructure varies from group to groupbut a commonpattern can be recognized.The cessationof feedingat the final moult from fifth copepodidto adultmale is alsomarked by profoundchanges in thearray of sensors carried along the paired antennules. Someof thesechanges are correlated with the cessation of feeding but comparativestudies indicate that other changesare linked to the onsetof sexual maturity and, in particular, to mate location behaviors.

THE STRUCTURE AND BIOLOGICAL SIGNIFICANCE OF WATER CURRENTS IN PREDATOR-PREY INTERACTIONS AND CHEMICAL COMMUNICATION. T. Breithaupt,Universitat Konstanz, Fakultat fiir Biologic,Postfach 5560 M 618!, D-78434 Konstanz, Germany

Hydrodynamicreceptor systems have been described and studied in detailin a variety of aquaticorganisms, including crustaceans. Little is known,however, about the physical parametersof the stimuli to whichthey haveadapted. Using modern techniques laser anemometry,flow visualization! flow fields were investigated that are created by swimmingand breathinganimals and that, in naturalcontexts, are detected and processed by hydrodynamic receptorsystems. Swimming fish cavefish Astyanax fasciatus and the trout Salmogairdnerii! createa laminarflow field aroundthe headregion bow wave!. Every tail beat,in contrast, evokesstrong turbulent water disturbancesthat detachfrom the fish and travel, for a considerabledistance and time, through the water in theform of stablevortex rings. Behavioral studiesindicate that blindfolded crayfish Procambarus clarkii!, catchingsmall fish, useboth bowwaves and vortex rings for hydrodynamicorientation. Water currents can also convey chemicalinformation about the sources of disturbance,Lobsters Homarus americanus! use self generatedcurrents both for breathingand for the dispersalof their urine. Urine borne pheromonesare used by conspeciflicsto recognize the dominant animal from previous fights. Detailedstudy of flow patternsand pheromone release revealed a sophisticatedapparatus for the directionaland temporal control of chemicalsignals. This example reflects the tight coupling betweenchemical and hydrodynamicstimuli.

15 "VIRTUALPLANKTON": A NOVEL METHOD FOR INVESTIGATING ZOOPLANKTONPREDATOR-PREY INTERACTIONS. M.C. Brewer, Center for Great LakesStudies, University ofWisconsin-Milwaukee, 600E. Greenflield Ave., Milwaukee, WI 53204, USA Theconservative swimming hypothesis CSH! states that individual Daphnia swimming behaviorhas evolved to maximizefitness in thepresence of predators. Numerous chemical and physicalenvironmental cuescombine toshape Daphnia's swimming behavior atany moment. Specifically,the CSH predicts that a Daphnia's swimming behavior relative to thebehavior of othermembers of the population affects predation risk. Individualsthat swim in a mannerthat differsfrom their neighbors become more conspicuous tovisually cued planktivorous fishand therefore,more vulnerable to predation. Thisprediction was tested using computer simulated "virtual Daphnia". Individual fish weretrained to attacksmall dots on a computermonitor that moved in a mannerthat mimics Daphnia'shop-and sink swimming behavior. This system was used to test the hypothesis that fishshow a preferenceforindividual virtual Daphnia that swim differently from a background "population"of other virtual Daphnia.

SENSITIVEPERIODS IN THE NEUROBIOLOGICALAND BEHAVIOURAL DEVELOPMENTOF FISHES. H.I. Browman,Department of Fisheriesand Oceans Canada,Maurice-Lamontagne Institute,Marine Productivity Division, 850 Route de la Mer, P.O. Box 1000,Mont-Joli, Quebec,GSH 3Z4, Canada Anoverview of neurobiological andbehavioural development in fishes will be presented. Sinceit would be impossible toprovide details for every sensory system and/or behaviour in the timeavailable, vision and visually-guided foraging behaviour willbe emphasized. Themanner inwhich the developmental trajectory presented forthe visual system can be generalized toother sensorymodalities willbe evaluated. Theconcept ofontogenetic sensitive periods SPs!, which havebeen defined atseveral different biological levels, will be used as an example of the possibleinteractions between a fish's neuroethological development andits ecology. For the purposesofthis discussion, SPsrepresent restricted anddiscrete temporal windows during which ananimal's developing organ systems are particularly susceptible toenvironmental influences. It isasserted thatSPs atdifferent biological levels embryological, neurobiological, ethological andecological are hierarchically interrelated. If this is so,the environmental conditions to whicha fishis exposed during its development mayhave fundamental consequences forhow it transducessensory information and, therefore, for howit behaves.

16 CEPHALOPOD SENSORY NEUROBIOLOGY. B.U. Budelmann, Marine Biomedical Institute and Departmentof Otolaryngology, University of TexasMedical Branch, Galveston, TX 77555-0863, USA

Cephalopodsare the mosthighly evolvedinvertebrates. With only a few exceptions,they are visually oriented, fast moving predators with highly effective sense organs and a sophisticatedbrain. Thedegree of complexityof thesesystems differs in thevarious cephalopod groups,depending upon the demandsof their lifestyleand the environment in which theylive. This paper will briefly outline the structure, function and biological significanceof the sense organs cephalopodspossess, as well as highlight some of the capabilities of their nervous system. Specialemphasis will be placedon their vertebrate-likeeyes which, most likely, do not see colors but, instead, the plane of polarized light; their vestibular analoguestatocysts with receptorsystems for linear and angularaccelerations; their control systemfor compensatoryeye movements which is similar to the vertebrate vestibulo-oculomotor reflex VOR!; their lateral line analoguesystem; the questionwhether or not cephalopodscan hear; their touch and distant chemoreceptors;their recentlydiscovered neck proprioceptor organ which monitors theposition of the head relative to the body; and their highly centralizednervous systemwhich is capable of different forms of learning and memory.

THE SENSORY PHYSIOLOGY OF COPEPOD NAUPLII INVESTIGATED USING LASERSCANNING CONFOCAL MICROSCOPY. M.H. Bundy'and G.-A. Paffenhofer, Skidaway Institute of Oceanography,10 OceanScience Circle, Savannah,GA 31411. USA. Present address: Great Lakes Environmental Research Laboratory, NOAA, 2205 Commonwealth Blvd., Ann Arbor, MI 48105, USA!

The functional morphologyof the first and secondantennae Al and A2! of the nauplius IV of the calanoid copepodsEucatanus pileatus and Centropagesvetificatus was investigated using laser scanningconfocal microscopy LSCM!. E. pileatus nauplii create feeding currents and move constantly, while C. velificatus nauplii do not createa feedingcurrent and move in intermittent jumps. The roles of mechanoreceptiveand chemoreceptivesensilla on the Al and A2 of the nauplius are discussedin terms of the remote detectionof food particles and the control of swimming behavior.

17 THEROLE OF PHOTORECEPTIONIN THE SWARMING BEHA VIOR OF THE COPEPODDIOITIVONA OCULATA. E.J. Buskey, J.O. Peterson andJ.W. Ambler, The UniversityofTexas atAustin, Marine Science Institute, Port Aransas, TX 78373, USA Thecopepod Dioithona oculata forms dense swarms near mangrove proproots that are centeredaround shafts of lightpenetrating themangrove canopy. These swarms form at dawn anddisperse atdusk, and light seems tobe an essential cuefor swarm formation. Insitu and laboratoryobservations of swarming behavior were recorded using video cameras, andthe swimmingbehavior ofthe copepods anddensity ofthe swarms were quantified using video- computermotion and image analysis techniques. Swarms canbe created inthe laboratory under lightshafts created with fiber optics. Swarm formation canoccur atlight intensities aslow as 0.1limol photons m s'. Copepodsreversetheir swimming direction whenthey encounter light intensitygradients near the edge of a lightshaft, maintaining theswarm. Swarm formation appearstohave anendogenous rhythm,as copepods willnot form swarms atnight under a light shaft.In si uobservations ofswarms indicate that densities ofcopepods inswarms can exceed 80copepods ml'. Swarmscanbe maintained evenduring period when tidal currents exceed 2 cms ',so that these 0.8mm in length copepods sustainswimming speedsof 5 body lengthss for' periods ofhours. Swarm formation mayprotect thecopepods frompredation by planktivorousfishby allowing them tomaintain their position within the mangrove proproot habitat.Planktivores wererarely observed under the mangrove canopy, which is often populatedwith piscivorous fish.

EFFECTSOF SEDIMENTLOADING ON FOODPERCEPTION AND INGESTION BYFRESHWATER ZOOPLANKTON. N.M.Butler, Flathead Lake Biological Station, The Universityof Montana, 311 Biostation Lane, Poison, MT 59860,USA Suspendedinorganic sediments, suchas clays and silts, are an important non-point source ofpollution inaquatic systems throughout theworld. In the lakes ofwestern Montana, the intensityofsediment loading isstrongly influenced byland use patterns. The presence of suspendedparticles canaffect not only the net primary productivity, aslight penetration andthe euphoticzone are reduced, but can also affect the availability of food to theherbivorous zooplankton.Themajority ofresearch onthe effects ofsediment loading onzooplankton feedinghave centered onorganisms which are not naturally associated withturbid environments. InSwan Lake, an oligotrophic lakelocated innorthwestern Montana, there isa closeassociation betweenzooplankton population development andseasonal maxima inturbidity levels, suggesting thatthe community present inthe lake during peak turbidity levels isminimally impacted bythe presenceofsuspended sediments. HereI present theresults oflaboratory investigations intothe effectof suspendedsediments onfeeding b the copepod Leprodiapromus ashlandii, the dominantzooplankter inSwan Lake. Using P labeledalgae Chlomydomonas reinhardtii! offeredinclay suspensions overof a rangeof0 to250 NTU's, I have observed thateven at verylow levels of turbidity less than 25 NTU!, the presence of suspended particles hasa negativeimpact on feeding behavior and ingestion. NO PLACE TO HIDE: BIOLUMINESCENCE AND THE SENSORY ECOLOGY OF PELAGIC CRUSTACEANS. J.F. Case, Marine Science Institute and Department of BiologicalSciences, University of California,Santa Barbara, CA 93106,USA

The pelagic environmentis a continuumlacking fixed pointsof referenceexcept gravity, downwelling light and temperaturetransitions. It is transparentand almost universally lacks concealment. Micronecton numbers are low. Most micronecton faunal biomass is constituted of bioluminescentanimals. Prominentamong these are euphausids,mysids and decapods. While chemo- and mechanoreceptionare well developedin all these,the physics of the environment arguesthat vision coupledwith bioluminescencedominates their long range interactions. Bioluminescenceis important in tracking targets,even non-luminescent ones, by their triggering of third-party luminescence;it offers counterilluminationconcealment in appropriatelylit depths; it probablyprovides signalling among conspecifics; and it mightallow rapidestimation of local faunal structure, for exampleduring vertical migration when predator/preynumbers at various depthsare critically valuableinformation. The interplayof visionand bioluminescence in both predation and concealmentwill be discussedon the basis of investigationsof compoundeye physical optics, electrophysiologicalcharacterization of compoundeye receptivefields, behavioral experiments, and field observations.

PREY RESPONSES TO SCYPHOMEDUSAN FLOWFIELDS DO THEY EXPLAIN PREY SELECTION? J.H. Costello',B.K. Sullivan andC.L. Suchman,'Providence College,Providence RI 02918and ~University of RhodeIsland, Narragansett, RI 02882,USA

In si u time budgetsdemonstrate that three speciesof scyphomedusae,Aurelia aurita, Cyaneasp. and Chrysaoraquinquecirrha, spend 95-98% of their time swimming. Fluid motions createdduring swimming entrain prey and bring them to capturesurfaces. However, in situ preyselection differs for thethree species. We discussrelationships between predator flow field characteristics,prey swimming and escapepatterns and prey selectionby each species.

19 COMPOUNDEYES AND PHOTORECEPTIONIN MEROPLANKTONIC CRUSTACEANLARVAE. T.W. Cronin', N.J. Marshall, andR.L. Caldwell, University ofMaryland, Baltimore Co,Baltimore MD21228 USA; Sussex University, Falmer, Brighton BN19QG UK; 3University ofCalifornia, Berkeley, CA 94720,USA Larvaeofstomatopod anddecapod crustaceans possess paired compound eyessimilar to thoseofadults ofthe same species. Such larvae are generally planktonic forlarvae, the term is"meroplanktonic"! andpredatory, andthus face the usual demands ofmaking a living inthe plankton.Their compound eyes are used for orientation, migration, and shadow avoidance. Whilethere isat present nocompelling evidence fortheir involvement invisual tasks requiring imaging,analogies withpermanently planktonic crustaceans suggestthat the behavior served by larvalvision could be very complex. Since crustacean larvae pass through several developmentalstages,and finally metamorphose toa verydifferent adult form, larval compound eyesmust change radically throughout development. They typically increase in size and in ommatidialnumber with each larval molt. In some species, ommatidial optics are fundamentally alteredat metamorphosis.Mostdramatically, in stomatopods, larval eyes are so different from theeyes of thepostlarvae and adults! that in a singlemetamorphic molt, the larval retina is replacedwith an entirely new adult-type photoreceptor array.

QUALITATIVELYDIFFERENT RESPONSES OF DAPHNIA CLONES TO THE PRESENCEOFPREDATOR SMELL. L. DeMeester, Laboratory ofAnimal Ecology, Universityof Gent, K.L. Ledeganckstraat 35,9000 Gent, Belgium Theresponses of Daphnia. to the presence of predators e.g. fishes! that have been reportedinthe literature include several behavioral e.g. phototactic behavior, overall excitation, aggregation!andlife history traits e.g. size at maturity!. It is suggestedthatshowing all responsestogether may be maladaptive, at least under certain circumstances, andthat the responsestothe presence ofpredator-mediated chemicalsmay be clone-specific qualitatively in additionto quantitatively. A comparisonof the results on changesinduced by thepresence of fish-mediated chemicalsin two behavioral characteristics, phototactic behavior and overall excitation, of Daphniaclones isolated from contrasting habitats, indeed indicates thatthe two responses are tosome extent uncoupled. A hypothetical receptor-effector pathway isproposed toaccount for geneticdifferences in both nature and degree of the response tothe presence of specific predators.Itis noted that our results also imply that the observation ofan absence ofa specific responsetothe presence ofa predatorina given Daphnia clone not necessarily isproof of the absenceof functional receptors forkairomones released bythat predator.

20 PREY DETECTION AND ATTACK PERFORMANCE IN EUCHAETA RIMA NA, A PREDATORY CALANOID COPEPOD. M.H. Doall', J. Yen, and J.R. Strickler, 'MarineSciences Research Center, State University of NewYork at Sony Brook, Stony Brook, NY 11794-5000,USA. Center for Great Lakes Studies,University of Wisconsin-Milwaukee, Milwaukee, Wl 53208, USA

The sensoryand attackperformance of Euchaetarimana, a predatorycalanoid copepod, is assessedthrough behavioral analyses of interactions with smaller calanoid species. Predator/preyinteractions are categorizedbased on the behavioralresponse and capturesuccess of the predator, E. rimana. Three categoriesof interaction are defined: 1! escape,in which E. rimana fails to recognizethe stimulusas prey and jumps away from it; 2! attack and miss, in which E. rimana recognizesand attacks i.e., lunges toward! a prey item but does not successfully capture it; and 3! attack and capture, in which E. rimana recognizes and successfullycaptures a prey. Preyrecognition efficiency is computedas the numberof attack attempts divided by the total number of interactions. Attack efficiency is computed as the number of successfulcaptures divided by the number of attack attempts. Preliminary analyses indicate that E. rimana can perceivea prey outsideof its attackvolume, and acceleratetoward the three-dimensionallocation of the prey until within striking distance. The attack volume of E. rimana is describedby plotting prey locations at the momentof attack around a standard three-dimensional orientation of E. rimana.

OPTIMAL SWIMMING BEHAVIOR IN ZOOPLANKTON. S.I. Dodson, Departmentof Zoology, University of Wisconsin, 430 Lincoln Drive, Madison WI 53706 USA

The ConservativeSwimming Hypothesis CSH! placeszooplankton swimming behavior within an ecological and evolutionary context:

zooplankton exhibit conservative swimming behavior over a wide range of environmentalconditions. We hypothesizethat conservativeswimming is the result of a balanceof adaptiveecological strategiesthat optimize fitness in the presence of predators.

The CSH synthesizesprevious information especiallyfor freshwaterzooplankton such as Daphnia! from different fields of freshwater ecology: chemical communication, feeding behavior, predator-preyencounter rates, predator sensitivity to variability in swimmingactivity, and synergismsamong independentphysical and biological factors. The CSH usesknowledge aboutboth feeding and predator-preyecology to makepredictions about zooplankton swimming behavior over a wide range of interacting physical and biological conditions. Testablepredictions of a graphicalmodel of the CSH include: 1! Individual swimming behavior affects feeding and population growth rates, 2! Food concentrationsand predator encounter rates interact to produce conservative swimming, 3! Food concentration, above starvation levels, will not affect swimming behavior, 4! Uniform low-variance! swimming behavior is a defense against visual predators, and 5! There are non-linear synergistic! interactions between light level and predator smell kairomone concentration!.

21 PREDATOR-PREYINTERACTIONS IN CTENOPHORES. T. Falkenhaug andO.B. Stabell,The Norwegian College ofFishery Science, University ofTroms6, Troms6, Norway Twospecies of ctenophores coexist in thenorth-east Atlantic, one genus Bolinopsis! foragescrustaceans, while the other genus Beroe! feeds exclusively on the former. In laboratoryexperiments, Bolinopsis demonstrated anescape response to mechanical stimuli directedtowards thefrontal lobes; while chemical stimuli, inthe form of water conditioned by thepredator, gave no detectable responses. Physical contact with a predator,observed in experimentsasa direct touch between thesides ofBolinopsis andthe rear end of Beroe, initiated no flightresponse. No detectableincrease in searchbehaviour by Beroe,measured as swimmingactivity, could be found, neither when stimulated with water conditioned by Bolinopsis,norwhen stimulated withextracts ofhomogenised specimens ofthe prey. Beroe turnstowards a prey, however, asa resultofa mechanicalstimulus onthe sides of thebody, probablyinitiated bywake ofa passingprey,as demonstrated byweak water jets from pipettes. Jetsof waterconditioned byBolinopsis caused noincrease inthe turning response. Turning towardsa prey mostly resulted indirect contact bythe 'lips', further initiating a rapid feeding responsebyextension of the mouth opening, and ingestion of the prey by sucking.The importanceof chemical stimuli in thefinal stage of preyselection was confirmed bylack of mouthextension following contact with glass pipettes, whereas mouth extension andfeeding behaviour,directed towards the wall of a glassjar, was observed when tissue from Bolinopsis wassqueezed between the mouth opening and the wall of thejar.

COMPARISONOF DEVELOPMENTALCHANGES IN SENSORYANATOMY AND FLOW FIELDDYNAMICS BETWEEN LARVAE AND POST-LARVAEOF HOMARUSAMERJCANAS. L.G.Farley', T.Breithaupt, andJ. Atema', 'Boston University Marine Program, Woods Hole, MA 02543, USA, Universityof Konstanz,D-78434 Konstanz, Germany Afterhatching, the lobster Homarus nmericanus hasthree pelagic larval stages I-III! and one transitionalpost-larval stage IV! before settling into a benthicexistence. Morphologically, larvaeare mysid shaped,andhave feathery exopodites onthe thoracic appendages thatare capable ofgenerating currents. The metamorphicmolt occurs between stage III larva!and stage IV post-larva!,where there is a transitionfrom themysid shape tothe adult lobster morphology. During the post-larval stage, the thoracic exopodites are regressedand the pleopods of the abdomen areused for swimming. Very little is knownabout how larval andpost-larval stages obtain sensory information from their respective environments. Since currents which passover the lateral antennule may contain sensory information, both the sensory anatomy of the lateral antennuleandthe flow flield dynamics ofthe currents arebeing examined. Thestage I lateral antennule the organofolfaction inthe adult lobster! does not possess chemosensory aesthetasc sensilla, butinstead possesses a largedistal giant sensillum. Anatomical studies using DIC microscopy showed thatthe presumptive nerve fibersatthe base ofthe giant sensillum develop intoaesthetasc sensilla. This provides preliminary evidence thatthe giant sensillum maybe chemosensory sensillum. Inaddition toanatomical studies, comparative flow fieldanalyses were performed onlarval stages I-III and post-larval stageIV toexamine thepossible information/feedingcurrentsproduced byeach stage. During'the larval stages, thethoracic exopodites producecurrents which are capable ofdrawing particles from the posterior aswell as particles anterior over theantennules andmouthparts. Thepost-larvae generate verypowerful pleopod currents bywhich they direct theflow from anterior toposterior. From the flow field analyses, it appears thatlarvae and post-larvae generatecurrents which would allow for chemicals to encounter chemoreceptive organs and these currents mayalso increase prey encounters, asis knownfor post-larvalstages.

22 A TECHNIQUE FOR NONINVASIVE DETECTION OF NEURAL AND MUSCULAR ELECTRICAL EVENTS DURING THE ESCAPE RESPONSE IN LARVAL FISH. D. Featherstone,C. Drewes,and J. Coats, 'BekesyLaboratory of Neurobiology,Pacific BiomedicalResearch Center, University of Hawaii,Honolulu, HI 96822,department of Zoology,Iowa StateUniversity, Ames, IA 50011,USA., Departmentof Entomology,Iowa State University Ames, IA 50011, USA

In most teleost fish, an escaperesponse occurs when a sudden stimulus via one or severalsensory modalities! causes one of a pairof Mauthner M-! cellsin the fish hindbrainto fire a singleaction potential. This actionpotential, as it travelstailward within the spinalcord, excites motor neurons which, in turn, activate axial muscle. We present a noninvasive electrophysiologicaltechnique for measuring,in intactlarval fish, the followingescape-related parameters:1! The conductionvelocity of the Mauthnerspike as it travelscaudally within the spinalcord. 2! Time from deliveryof a standardizedacoustical and vibrationalstimulus to Mauthnerspike initiation. 3! Delaytime from Mauthneraxon spike to motoneuronpotential. 4! Probabilityof an escapebehavior in responseto a stimulus. 5! Electromyographicburst number and duration representingthe initial, fast body bend of the fish as it turns away from the stimulus,and subsequenttail flips as it swimsaway.! This techniquemay be usefulfor developmental,toxicological, or neurobehavioralstudies which require repeatedmeasurements on the same animal.

THE ESCAPE BEHA VIOR OF MARINE COPEPODS IN RESPONSE TO A QUANTIFIABLE FLUID DISTURBANCE. D.M. Fields and J. Yen, Marine Science ResearchCenter, StateUniversity of New York, Stony Brook, NY 11794-5000USA

Copepodsare subjectto high predationrates throughout much of their planktoniclife. As a resultpredator detection and avoidance are crucial to the survivalof individuals. This studyexamines the escape reaction of 4 oceanicspecies of copepods from a varietyof different habitats! in responseto a quantifiablefluid dynamic disturbance. Of the animals studiedone species Pleuromamma xiphias! shows an extensivevertical migration being found between 20 meters during the night and 700 metersby day. Two other species,Euchaeta rimana and a cyclopoidcopepod, are offshore surface dwellers while Labidocera madurae is foundprimarily at the surfacein shallow waters. Fluid characteristicssuch as shear,velocity and acceleration ratesat the point of escapeare examined and compared for the differentspecies. Preliminary data suggeststhat spatial variation in fluid velocity is most predictive of the escapelocation, however, each specieshad a different threshold that elicited the escapereaction. Onceinitiated the escapereaction for all the specieswas extremely rapid. For the larger animals-studiedthe escapespeed surpassed 1000 mm/s with accelerationrates up to 14 times the accelerationdue to gravity. The variability in stimulusthreshold and escapespeed between the differentspecies may be a reflectionof the differentpredation pressures on theseanimals.

23 SENSORY PH YSIOLOGY AND BEHAVIOR OF CRAB LARVAE DURING HORIZONTALTRANSPORT. R.B. Forward, Jr., Duke University Marine Laboratory, Beaufort, NC 28516, USA

Manyestuarine decapod crustaceans release their larvae at specifictimes relative to environmentalcycles. They are then transported outof the estuary and undergo development incoastal areas. Using the blue crab Callinectes sapidus asan example, aspects ofthe sensory physiologyandbehavior involved intransport back to the adult habitat bythe postlarval stage megalopa!will beconsidered. Field studies indicate transport onshore to themouth of an estuaryisby wind generated surface currents, while selective tidal-stream transport isused for up-estuarymovement. Chemical cues in offshoreand estuarine waters induces separate behavioralresponses toenvironmental factorswhich underlie onshore andup-estuary transport. A biologicalrhythm in activityand photoresponses maintain megalopae near the surface for onshoretransport during the day. Duringup-estuary transport megalopae arein thewater columnduring the rising tides at night and are on, or closeto, the bottom at all othertimes. Theascent during rising tides could result from a tidalrhythm in activityor behavioral responsesto changes in environmental factors such as temperature, pressure and salinity. Responsestothese factors are frequently used for depth regulation among zooplankton. A considerationof the activity rhythm, and the physiology of responses toenvironmental factors indicatesthat the ascent is cued by the rate of changein salinity.

BEHAVIORALSENSITIVITY TO NEAR-UVAND BLUE-GREENLIGHT IN DEEP SEA CRUSTACEANS.T.M. Frank and E.A. Widder, Harbor Branch Oceanographic Institution,Ft. Pierce,FL 34946,USA Severalspecies ofdeep-sea crustaceans possess unusually high spectral sensitivity to near-UVlight, measured electrophysiologically, inaddition to the expected spectral sensitivity peakin theblue-green. A protocol was developed to determine if these species exhibited behavioralsensitivity tonear-UV light as well. Experiments wereconducted on6 speciesof deep-seacrustaceans 3pulative dichromats withthe two spectral sensitivity peaks, and 3 putativemonochromats, witha singlepeak in theblue-green. These experiments were conducted1! to determineif there were behavioral differences to light between putative dichromatsandmonochromats, and2! to measure andcompare behavioral thresholds tolong andshort wavelength light. Results indicate that 1! there are no wavelength specific behaviors, and2! that the putative dichromats areequally sensitive tonear-UV andblue-green light,while themonochromats arealmost a log unit less sensitive tonear-UV vs.blue-green light. The possiblefunctional significance ofthis unusual sensitivity tonear-UV light in deep-sea organisms asit relatesto verticalmigration and bioluminescence will bediscussed.

24 LARVACEAN HOUSES DETER PREDATION BY FISH AND CHAETOGNATHS. C. Gait, Department of Biological Sciences,California State University, Long Beach, CA 90840-3702, USA

Oikopleurids,frequent prey of zooplanktonand fish, occupyrenewable, mucous, feeding houses.Do larvaceanhouses also deterpredation? I examinedlarvaceans' behavioral responses to visual predators juvenile fish, to 4 cm long! and non-visualpredators chaetognaths,to 1.3 cm!. As prey I used Oikopleuralongicauda up to 1.2 mm body length and 5 mm house diameter. Both predatortypes readily detectedand ingestedO. longicaudawhen it swamfreely without a house.Detection range was a few mm for chaetognaths,which detectthe prey's rapid swimming vibrations, and more than 10 cm for visual fish. In contrast, chaetognathsdid not strike at occupiedhouses, presumably because the gentlebeating of the larvacean'stail provided insufficient sensorystimulus. Juvenilefish showedfour interactionswith occupiedhouses: A! small fish peckedat but failed to disturb occupiedhouses; B! larger fish peckedat the house, triggering an escaperesponse in which the entire occupiedhouse rolled away; C! some fish attackedthe house, yet O. longicaudarapidly exited the houseand swam away; D! somefish ingestedthe occupied house, then rapidly and invariably regurgitatedit, while retaining the larvacean. Oikopleurids occupyinghouses are protectedfrom predation in a variety of ways comparedto highly vulnerable, free-swimming larvaceans.

BEHAVIORAL BIOASSA YS EMPLOYING DA PHNIA FOR DETECTION OF SUBLETHAL EFFECTS: RESPONSES TO POLARIZED LIGHT. J. Gokcen and D. McNaught, Departmentof Ecology, Evolution andBehavior, University of Minnesota,1987 Upper Buford Circle, St. Paul, MN 55108, USA

The swimming responsesof Daphnia pulicaria to both polarizedwhite and UV light were examined. Both sets of responseswere employed as behavioral bioassaysto investigatethe effects of sodium bromide NaBr! on their physiology. NaBr was chosenbecause it may be used in the Laurentian Great Lakes to eradicate the zebra mussel. The control responses to polarized light involved an orientation at 90' to the e-vector. With the addition of NaBr the responsebecame random. An EC>0of 9.9 x 10 M NaBr wascalculated, using the statistic Raleigh's Z to determinethe significanceof the plane of orientation. In contrast, the control responseto polarized UV light was a random orientation to the e-vector. However, as NaBr concentrationsincreased, Daphnia began to exhibitrepetitive behavior. At both10" and10 M NaBr, the organism consistentlyoriented itself between0-60' to the e-vector of polarized light. An EC>0of 3.0 x 10 M NaBr was calculatedfor this response. A possiblemechanism to accountfor the toxicity of this mild sedativeis the blocking by the bromide ion of chloride channels involved in transmitting impulses.

25 THEINFLUENCE OF KAIROMONESAND FOOD CONCENTRATION ON THE RESPONSEOF DAPHNIA TO CHANGINGLIGHT INTENSITIES. E.van Gool and J.Ringelberg, University ofAmsterdam, Department Aquatic Ecology, Kruislaan 320,1098 SM Amsterdam, The Netherlands Dielvertical migration DVM! ofplankton animals likeDaphnia isconsidered a strategy todiminish predation, forinstance, byvisual predators likejuvenile fish. Disadvantages arelow temperaturesandlow food concentrations atgreater depth and models predict that the change infitness depend onfood availability andpredation pressure. Theamplitude ofDVM isvery variable,indeed. So it washypothesized thatDaphnia hasa mechanismtodecide whether to migrateornot, depending onthe value ofboth factors. A firststep was to quantify the influenceoffish kairomones andfood concentration onphototaxis. Thisphototaxis isconsidered thebasic behaviour of migration. Asa stimulus,themaximum relative increase in light intensityprevailing atsunrise wasused and parameters suchasthe percentage ofresponding animals,displacement velocity, and latent period were determined. Wefound a significant influenceofkairomones andfood availability onthe percentage ofresponses andon the latent period.

RESPONSEPATTERNS OF A CTENOPHORE:PLEUROBRANCHIA PILEUS. W.Greve, Biologische Anstalt Helgoland, Zenale Hamburg, 22607 Hamburg, Germany Thetentaculate ctenophore Pleurobrachia. pileusis a highlysuccessful species. Since 400million years the lower Devonian period! its organization seems tohave remained almost unchanged.Thismay be due tothe simple andefficient wayin which itsresponse patterns help to saveenergy and avoid destruction. The responses of P. pileus are organized onseveral hierarchical levels. Theselevels are: the whole organism thesingle tentacle as a complexof organs the single organ Withinthese levels, atleast 31 discrete sensory responses andreactions canbe discriminated. A detailedflow diagram of the behavioral responses hasbeen determined anddocumented in a scientificfilm.Special attention isgiven tothe synchronous andasynchronous handlingof thetentacles. Thismay be an important means tosave energy. The prey-catching behavior thus hasbeen documented in 17parallel phases. The responses tovibrations, scyphomedusan stinging,contact withBeroe graci lis, pressure changes, temperature changes,and other possible cues are demonstratedand discussed.

26 METAMORPHOSIS IN MARINE INVERTEBRATES: THE NEED FOR SPEED. M.G. Hadfield, Kewalo Marine Laboratory, Pacific Biomedical ResearchCenter, University of Hawaii, Honolulu, HI 96822, USA

Accumulatingevidence supports a hypothesisthat external,chemically sensitive excitable cells initiate metamorphosisin swimming larvae of most benthic marine invertebratespecies. The current model statesthat specific molecular receptorson the cell surfaces,upon exposure to thresholdlevels of specificexternal ligands, producedepolarization of the cell membrane,and the electrical stimulus is transmitted to responding tissues through the nervous system. Support for this hypothesis comes from ! the rapidness of the metamorphic response, ! the metamorphicstimulatory or inhibitory activity of known neuro-activeagents, including a positive responseto excesspotassium ion in the medium, and ! demonstrationof altered electrical patterns in the brain of an invertebratelarva. For the larva to respondso rapidly to external chemical stimulation, it must be exceptionally "prepared" for metamorphosis,a criterion that is met by the developmentof metamorphiccompetence. Competentlarvae needonly nervous stimulation to commencemetamorphosis. Great congruity of a phenomenonacross a groupof organismsis usually explainedby evolutionary homology. However, the diversity of phyletic lineagesand larval typesdemonstrating chemoreception-neurostimulation of metamorphosis make homology highly unlikely. Rather, the time of settlementand metamorphosisis probably the most vulnerable in the lifespan of marine invertebrate animals, and convergentevolution of neuro-stimulatedmetamorphosis has been nature's repeatedresponse to this "need for speed."

MIGRATION AND SPAWNING IN CNIDARIANS. W.M. Hamner, Departmentof Biology, University of California, Los Angeles, CA 90024-1606,USA

Maintenanceof persistentpopulations of meroplanktonicorganisms over time requires that the planktonic phaseof the life cycle return to the site of initial fertilization in spite of oceanographic factors that promote dispersion. For cnidarians with benthic larvae and planktonic adults, the medusaemust not only return to a site suitablefor larval settlement,but they must also return simultaneouslyin numberssufficiently large so that planktonic spawning is possible. Spawningis often accomplishedwithin highly aggregatedmasses of sexuallymature medusae. Spawning, therefore, requires the neurological equipmentboth for returning to a specific location at sea and for recognizing the presenceof other reproductively mature medusae.The issuesof planktonicdispersion, migration, and spawningare discussedin relation to the life history, behavior and neurobiologyof scyphomedusae,with specific examplesfrom recent research on the moon jellyfish, Aurelia aurita, and with speculationsabout other taxonomic groups of Cnidaria.

27 BEHAVIOURAL RESPONSES TO CONTACTBETWEEN THE SCYPHOZOAN PREDATORCYANEA CAPILLATA AND THE PREY AURELIA AURITA. L.J. Hansson, GoteborgUniversity, Kristineberg Marine Research Station, S-45034 Fiskebackskil, Sweden Theinter-specific relationship between two scyphozoanmedusae was studied in the Gullmarsfjorden,Sweden. Experiments weremade inthe field in order to study the behaviour whenthe predator Cyanea capillata L.! encounters anindividual ofthe prey Aurelia aurita L.!.An underwater videocamera, operated bySCUBA divers, was used torecord themotility patterns of the medusae. Theobserved reaction inA. aurita varied when different parts ofthe medusan bodywere broughtincontact with the marginal tentacles ofC. capillata. The umbrella margin ofA. aurita washighly sensitive andin this region ofthe body, contact with a singletentacle ofC. capillata wasenough toinduce a typical change inthe motility pattern. However, thenematocysts on thetentacles of C. capillata did not have to discharge in order to cause this response inA. auritu.The same behavioural change could be evoked by merely mechanical stimuli. Themedusa ofC. capiilafa also responded tomechanical stimulation. When a pulling forcewas applied to the tentacles, a change in both swimming direction and swim pulse frequencywere observed. Possible ecological significance of the behaviour is discussed.

SENSORYPHYSIOLOGICAL STUDIES OF THEFIRST ANTENNA OF CALANOID COPEPODS.D.K. Hartline and P.H. Lenz, Bekesy Laboratory of Neurobiology, Pacific BiomedicalResearch Center, University of Hawaii, Honolulu, HI 96822USA Oneof thekeys to survival ofcalanoid copepods isa rapid escape "jump" to sudden mechanicalstimuli. Recent electrophysiological studiesof sensory cells in the antennae ofthese animalshave demonstrated discharge ofgiant spikes inresponse tovarious mechanical stimuli ofsetae onthe distal tip of the first antennae Yenet al, J. Plankton Res. 14: 495 [1992]; Lenz andYen BuII. Marine Sci. 53: [1993]!. Inthe present studies, extracellular recordings ofnerve impulsetraffic inresponse tocontrolled mechanical stimulito the antennal tipwere made using themethods ofGassie etal. Bull.Marine Sci. 53: 96 [1993]! incalanoids. Abrupt water movements trapezoidal waveforms!, mimicking thetype of hydrodynamic signalpresent in potentialpredatory lunges, triggered responses in two reidentifiable giant units at water velocitiesaslow as 10 microns/sec. Thisis comparable towater velocity thresholds reported incalanoids forsinusoidal forms of mechanical stimulus. / Inanother electrophysiological approach, suction electrode record ngs were made from theantennal nerve of Gaussiaprinceps bycutting a smallwindom in'the~ Pentr'al exoskeleton at thebase ofthe antenna. Touching setae onthe distal tip elicited impulses picked upby the electrodes.Electrical stimulation through the same elect'rodd elicited a rapidall-or-none abductionof the long anteriorly projecting seta, ¹8 WeatherbyI etal. J. crust.Biol. 14: 670 [1994]!. Escapereactions insome calanoid copepods show a highsensitivity towater velocities forvibratory signals ofunusually highfrequency fora crustacean000Hz; see Herren etal., thisvolume!. The mechanoreceptors describedhere possess thecharacteristics needed tobe the detectorsof thedisturbances leading to theseescape reactions. Supportedby NSFOCE-8918019 and the Ida Russell Cades Foundation.

28 WATER FLOW EFFECTS ON ZOOPLANKTON ESCAPE BEHA VIORS FROM CORAL PREDATORS. K.B. Heidelberg, K.P. Sebens, and J.E. Purcell, Horn Point EnvironmentalLaboratory, Centerfor Environmentaland EstuarineStudies, The University of Maryland System, PO Box 775, Cambridge, MD 21613, USA

Studies addressing coral predator's effects on zooplankton assemblageshave not examined the role of the zooplankton behavior on capture efficiencies. The relationships betweencapture and escapebased on zooplanktonbehavior, coral tentaclesize, and water flow speed were examined for the two scleractinian corals, Meandrina meandrites and Madracis mirabilis. We usedan oscillatory, recirculating laboratory flume at the Discovery Bay Marine Lab in Jamaica. Zooplankton encounters with coral tentacles were filmed with a high magnification, CCD camerausing infrared back lighting and low, medium, or high oscillating flow speedsthat were comparableto local reef conditions. A wide rangeof taxa of zooplankton behavior was characterizedusing frame by frame analysisof the video footage. Prey escape abilities, flow speed,and coral specieswere all found to play an important role in modifying encounter and capture rates. These results explain why coral coelenteron contents do not correspond to ambient zooplankton assemblages.

BEHA VIORAL RESPONSES OF CALANOID COPEPODS TO QUANTITATIVE MECHANICAL STIMULI. C. Herren*, P.H. Lenz, and D.K. Hartline, BekesyLaboratory of Neurobiology, Pacific Biomedical ResearchCenter, University of Hawaii, Honolulu, HI 96822USA and *Marine ScienceProgram, University of SouthCarolina, Columbia, SC, USA

Recent advancesin electrophysiologicaltechniques have permitted measurementof physiological responsesto controlled mechanical stimuli in calanoid copepods Yen et al. J. Plankton Res. 14: 495 [1992]; Lenz and Yen Bull. Marine Sci. 53: [1993]!; Gassieet al., Bull. Marine Sci. 53: 96 [1993j!. We report here results of comparablework on behavioral responses to the same stimuli. Labidocera maduraewere tetheredto a fine wire and stimulatedby water movements produced by a small piezo-electrically driven sphere positioned near by Gassieet al. 1993 loc. cit.!. Escape"jumps" were monitoredvisually through a dissectingmicroscope. Abrupt trapezoidal! water movementsof as little as 10 nm completed in 100 microseconds a symmetricalreturn movementwas delivered 2.5 mseclater! weresufficient to elicit responses in sensitive animals. Responsethresholds were measured to a trapezoidally-modulatedsine wave stimulus of 10 mseconset, 10 msecconstant amplitude and 10 msecoffset times, for frequenciesfrom 100 to 2400 Hz. Highestdisplacement sensitivities were observedaround 1000Hz, with sensitivities falling off graduallyat lower frequenciesand moreprecipitously at higherfrequencies. The velocity threshold,however, was near 10 microns per secondat 1000 Hz, paralleling electrophysiologicalfindings. Bestvelocity sensitivities are compatiblewith a singlesensory impulsebeing sufficient to triggeIan escape reaction under some conditions. C.H. was supportedby an NSF REU fellowship.

29 HYDRODYNAMICSOF OLFACTORYANTENNAE. M.A.R. Koehl, University of California, Berkeley, CA 94720-3140,USA

A criticalstep in theprocess of olfactionis thearrival of chemicalsignals from the environmentto thesurface of a chemosensorystructure. Many zooplankton use antennae bearingarrays of microscopichairs to pickup chemical signals from the surrounding water. Thefluid flow field in theimmediate vicinity of a sensoryhair determines the rates at which moleculesarecaptured, hence the hydrodynamic design of anantenna provides the first step in filteringenvironmental chemical signals. We have been using physical and mathematical models to identifywhich aspects of the morphologyand motionof antennaeare importantin determiningthe flow microenvironmentof the sensory hairs they bear.

BEHA VIOUR AND ECOLOGY OF CLADOCERA WITH FOCUS ON THE INFLUENCEOF CHEMICAL SIGNALSIN THEIR ENVIRONMENT.P. Larsson, Universityof Bergen,5007 Bergen, Norway

Thispaper gives an overview of howbehaviour, morphology and reproduction in filter feedingCladocera are mediatedby chemicalsignals from predators,competitors and conspecifics.The Cladocerans arepreferred prey for manyfishes and invertebrates andthey gotboth increased vigilance and direct behavioural responses to chemicals released bythese predators.They seemto discriminatebetween both the typeof predatorsand their environmentalsituation, and may react with directavoidance, aggregations in swarms or diel verticalmigration. Their tendency to makeswarms and diel vertical migrations seems to be strongly modifiedby the food conditions. It has not beendocumented that the searchfor appropriatefood is chemicallymediated. Some species have cyclomorphosis with a periodic appearanceof helmetsand longer spines. It hasbeen demonstrated that at leastsome of these reactionsare chemically induced. Cladocerans combine sexual and asexual reproduction. Their parthenogeneticreproduction isin periods broken by formation ofmales and sexual resting eggs ephippia!.The change in reproductivemode is regulatedby bothphenological cues like photoperiod,as wellas food concentrations and the intensity of chemicalsignals from their conspecificsor other cladoceran species. Other lifecycle changes are also reported.

30 CRYPTIC BIOLUMINESCENCE IN THE MIDWATER ENVIRONMENT. M.I. Latz, Marine Biology ResearchDivision 0202, ScrippsInstitution of Oceanography,La Jolla, CA 92093, USA

One of the strategiesmidwater animals have adoptedfor remaining cryptic to silhouette-scanningpredators is luminescentcountershading, called counterillumination, in which downward-directedbioluminescence replaces oceanic light that has beenreflected or absorbed by thebody. Becausecounterilluminating animals respond directly to theiroptical environment, anunderstanding of thecontrol of bioluminescenceprovides an insight into thevisual processing capabilitiesin systemswhich are poorly understood.In the penaeidshrimp, Sergestes similis, downward-directedillumination detectedby the eyes results in light emission from modified portionsof thehepatopancreas. Bioluminescence matches the physical characteristics of oceanic light. Experimentalresults suggest that two physiologicalcontrol systems, one neural and the other hormonal,regulate the inductionand control of counterillumination.One hypothesis is that the inductionof bioluminescenceis linked to light adaptationof the eye. Ultimately, deciphering the control of light emissionin S. similis will aid in understandingthe ecological rolesof bioluminescenceand vision in predator-preyinteractions and trophicdynamics in the midwater environment.

NEURAL DEVELOPMENT IN THE PLANKTONIC AND EARLY BENTHIC STAGES OF THE PALINURID LOBSTER, JASUS EDWARDSII. M.S. Laverack, D.L. Macmillan and S.L. Sandow,Department of Zoology, University of Melbourne, Parkville Vic. 3052 Australia

Jasusedivardsii has a seriesof elevenphyllosoma stage larvae that are morphologically adaptedfor a fully planktonicexistence. These are followed by a puerulusstage which, although it hasthe generalbody form of the adult, is alsoadapted for swimming,and then by the first of the truly benthicjuvenile stages.Using transmissionelectron microscopy we compared transversesections of connectivesin theventral nerve cord of thefirst phyllosoma,the puerulus and the first post-puerulusstage at a numberof levelsalong its length. We found that the anteriorcord of thephyllosoma has approximately the same number of neuronsas the puerulus. This has implicationsfor our understandingof crustaceanlarval sensorysystems because previouswork showsthat by far thelargest number of fibresin thenerve cord are sensory. Fibre countsin the post-puerulusincrease in the expectedmanner. The cord structureof the puerulusand post-puerulus is the same as that found in theadult whereas that of thephyllosoma is not organisedin the sameway.

31 LECTIN BINDING TO SURFACE GLYCOPROTEINS ON COULLANA SPP. COPEPODA:HARPACTICOIDA! CAN INHIBIT MATE GUARDING. D.J. Lonsdale', T.W.Snell and M. Frey','Marine Sciences Research Center, State University ofNew York atStony Brook, NY 11794-5000, School ofBiology, Georgia Tech., Atlanta, GA 30320-0230, USA

Wetested the hypothesis that surface glycoproteins found on Coullana spp. are important mate-recognitionfactors. Femalecopepodites mostly C V's! of Coullanacanadensis Maryland!and Coullanasp. Florida!were treated with 0.1 mg ml of four lectinsthat representa variety of carbohydrateaffinities. The females were then washed and exposed to males.Binding of somelectins significantly reduced the ability of malesto recognize potential matesand initiate precopulatory mate guarding. Other lectin treatments had no significant effect onthis behavior. These data suggest that surface glycoproteins onfemale Coullana spp. are importantmating signals for males in therecognition of conspecifics. Our results also suggest thatdifferences in chemicalsignals among these sibling species may have evolved.

INVOLUTION, INTIMIDATION, ESCAPE: DEFENSIVE STRATEGIES IN PLANKTONICCOELENTERATES. G.O. Mackie, University of Victoria,Victoria, British Columbia, V8W 2Y2, Canada Confrontedwith damaging or potentially harmful stimuli some hydromedusae adoptan armadillo-likestrategy, pulling in theirappendages andclosing the bell at the bottom involution, or "crumpling"!. The responseis evokedby sharpcontact on exteriorsurfaces. The entire exumbrellarepithelium is a sensoryreceptor that conducts signals firing thenerves and muscles involved.In somemedusae and siphonophores crumpling is accompanied by dramatic visual displays,for instancethe blinding, sheet-like luminescence of Euphysa and the astonishing, blanchingresponse of Hippopodius.The display serves to emphasizethe impressive bulk of theselargish, slow-moving forms and is mediatedby conductingepithelia. For powerful swimmers,escape provides anobvious solution. A shortresponse latency isessential, and giant axonshave evolved as rapidconduction pathways in somectenophores Euplokamis!, siphonophores Nanomia! and hydromedusae Aglantha!. Some species are acutely sensitive to vibrationas well as to direct contact and have evolved sensory receptors resembling vertebrate haircells that can detect small mechanical displacements caused by water-bornevibrations.

32 UNCONVENTIONAL SIGNALLING MECHANISMS IN PELAGIC TUNICATES. G.O. Mackie, University of Victoria, Victoria, British Columbia, V8W 2Y2, Canada

Theindividual zooids of salpsand pyrosomes have well developedcentral and peripheral nervous systems but so far as is known there are no direct nervous connections between the zooidsin thesepelagic colonies. This is also true of colonialascidians and distinguishesthe Tunicata as a class from ectoproct bryozoans and cnidarian colonies, where the zooids are usuallydirectly interconnectedby nerves. Facedwith the challengeof respondingto sensory stimuli on a colonial basis and achieving coordinatedresponses in the absenceof a colonial nervous system, tunicate colonies have evolved alternative mechanisms. Didemnid ascidianshave reinventedthe nervoussystem in theform of a sensory-motornetwork of conductingmyocytes located in the tunic enveloping the zooids. Botryllids use their colonial blood vesselsas signallingpathways. Salps have excitable epithelia that play an essentialrole in coordinating escapelocomotion. Conductingepithelia are also known to occur in doliolids, but their function is unknown. Pyrosomeshave hit uponthe mostbrilliant solutionof all, usingphotic signalling to communicate defensive responses within and between colonies.

SENSORY ECOLOGY OF PELAGIC TUNICATES: MORE QUESTIONS THAN ANSWERS. L.P. Madin, Woods Hole OceanographicInstitution, Woods Hole, MA 02543, USA

There is still relatively little known about the natural history of gelatinousanimals in the plankton, and their sensoryecology remains largely a matter of surmise, based on limited morphologicaland behavioraldata. A variety of sensorystructures, either demonstratedor presumed,have been described in thethree major groups of gelatinousplankters. In thepelagic tunicates,these include photoreceptors of varyingcomplexity, and several structures that have been suggestedto be mechano- or chemoreceptors. Different kinds of environmental informationmay be importantfor differentscales of behavior.Feeding and predator avoidance arelikely to beaffected by near-fieldstimuli from visual,chemical or mechanicalsources, while far-fieldinformation such as gravity or gradientsof light, temperature,or pressureare likely to cuebehavior spanning larger time and space scales, such as vertical or ontogeneticmigration, aggregationand reproductive cycles. I will usesome examples of feedingbehavior, swimming orientation,and vertical migration by thaliaceansand appendicularians to illustrate the kinds of sensorymechanisms that seem likely to existin theseanimals, and could be rewarding avenues of research.

33 ORIENTATIONAND TRACKINGBY HYPERIIDAMPHIPODS. N.J. Marshalland M.F.Land, Sussex Centre for Neuroscience, University ofSussex, Brighton, Sussex BN1 9QG, United Kingdom Manymesopelagic animals have large eyes which are used in a varietyofways. Very littleis knownof theirnatural behaviours, however, because of the difficulties in observing them.Hyperiid amphipods have very large compound eyes and behave well when brought to thesurface. Using a tankbacklit with IR light and an IR sensitive video camera system, we wereable to presentthe animals with a varietyof stimuliand observe their reactions in "dark" conditions.Various species had previously been shown torespond tolight and dark bars by swimmingaway, or occasionallyapproaching the stimulus Land, M.F., J. Mar.Biol Assoc. UK72: 41-60 [1992]!. In thispaper we describe much more striking and predictable behaviour in responsetoa bluelight emitting diode LED 475nm!. Brachyscelus sp.swarmed around theLED assoon as it wasswitched on andboth Phrosina semilunta and Phronima sedentaria trackedthe LED as it moved.They did this either by tiltingthe body axis towards the LED, or swimmingalong with it a fewbody lengths away. Interestingly thepart of theeye used to trackthe LED was not the dorsal acute zone, present in all species,but a frontalregion of slightlyelevated acuity in thelower eye seeLand, M.F., J. Comp.Physiol. 164: 751-762, [1989]!.This is consistentwith the idea that the upper eye is for viewingsmall dark objects againstthe residual downwelling daylight, whereas the lower eye is concernedwith luminescent objects.

OBSERVATIONSON THE ANATOMY AND BEHAVIOUR OF THE CUBOZOAN CARYBDEARASTONI. G.I. Matsumoto, Flinders University of South Australia, Adelaide, South Australia 5001, Australia Thecubozoan Carybdea rasioni occurs throughout thePacific and is veryabundant in areasof South Australia. C. rastoni has been observed feeding in the field on mysids and larval fishand on Artemia inthe laboratory. The medusae occur in swarms and are closely associated withsand patches during the day butare not capable of attachment likeC. sivickisi! and move upto the surface atdusk for feeding.The species is dioecious and the males secrete a sperm strandthat is picked up by the female. Preliminary observations oncolloblasts andthe optic systemwill be presented along with field and laboratory observations onanatomy and behaviour.

34 PLANKTIVORY IN LARVAL FISHES: ENHANCEMENT OF FORAGING ON ZOOPLANKTON BY ULTRAVIOLET SENSITIVE VISION. F.A. McAlary, E.R. Loew, andW.N. McFarland. 'Wrigley MarineScience Center, USC, P.O. Box 398, Avalon, CA 90704, USA, and DepartmentPhysiology, VRT, Cornell, Ithaca, NY 14853,USA

Mostmarine and many fresh water larval fishes are obligate, diurnal, visual planktivores. Survivalof larvaedepends on findingand capturing food, which is usuallypresented in a patchy framework,as well as avoidingpredators. Mortality of larval fishestherefore can be high becauseof the uncertaintiesof findingan adequate supply of food. Successfulforaging depends not only on the availability of zooplanktonbut also the sensoryabilities of larval fish to detect their planktivorousprey. Feedingexperiments reveal that oneday old hatchlingsand older larvae are capableof detectingand engulfing zooplanktonin UV-A light alone. The basisof this sensorycapability is the presenceof a classof conephotoreceptors containing a visual pigmentthat maximallyabsorbs photons between 350 and 370 nm. We suggestthat this short wavelengthextension of the visual systemincreases the chanceof capturing prey, and may be widespread,especially amongst, larval fishes.

CHARACTERISTICS OF BROAD SPECTRUM NEURONS IN CRUSTACEAN OLFACTORYMIDBRAIN. D. Mellon,Jr., Departmentof Biology,Gilmer Hall, University of Virginia, Charlottesville, VA 22901, USA

I have recordedelectrical activity from broad-spectrum,multiglomerular neuronsin the crayfisholfactory midbrain. Intracellularelectrophysiological techniques were used to record responsesto odorant stimuli applied to the antennulesof isolated, perfused crayfish head preparations. I obtained records from three different classes of midbrain neurons that were identifiedboth by theirelectrical responses to odorants and by theirmorphology from biocytin- labeled,sectioned material. All threetypes responded to a complexmixture of five aminoacids as well as to solutions of a commercialfish food. At least one of the classesof rieuron also respondedto individualamino acids and to sugars. The responseproperties, as well as the morphologies,of the neuronswere unique to eachtype, consisting in TypeI of stimulus- dependentexcitatory postsynaptic potentials and superimposed impulse trains, in TypeII of stimulus-dependentinhibitory postsynaptic potentials, and in TypeIII of brieftrains of impulses thatexhibited frequency and impulse-number maxima to stimulusdurations that were nominally abovethreshold, the responses falling sharply to stimuliabove or belowthis narrow range. All threecell typeshad extensive, multiglomerular dendritic arbors in the olfactorylobe, but each of theirrespective branching pattern morphologies was distinctive. Two of theneuronal types hadadditional dendrite branches in thelateral antennular neuropile and the olfactory-globular tractneuropile. I concludethat these broad-spectrum neurons are part of a parallelolfactory pathwaythat is separatefrom the putativequality coding olfactory circuitry by whichthe crayfish nervous systemmay discriminatebetween different odorant stimuli.

35 THE USE OF NOVEL CHEMO-INDUCTIVESUBSTRATE RESOLVES FACTORS INVOLVED IN RECRUITMENTOF CORAL LARVAE. A.N.C. Morseand P.T.Raimondi, Marine Biotechnology Center and Center for CoastalStudies, Marine Science Institute,University of California,Santa Barbara, CA 93106,USA

Previousstudies from our laboratoryreported that planula larvae of theshallow-reef Caribbeancoral, Agaricia humilis, have a stringentrequirement for detection of a specific chemicalcue for activationof metamorphosis.The result is rapid,permanent attachment to hardreef substrate and development to the single polyp stage. The chemical morphogen, associatedwith the cell wallsof tropicalspecies of non-geniculatecoralline algae Corallinaceae!,hasbeen isolated and partially characterized. Manipulation of the hydrophobic propertyof thismorphogenic compound has facilitated its concentratedadsorption to an inert resinbead matrix that can then be secured to a testsurface by embeddingin adhesive. This novelchemo-inductive substrate, containing a potent morphogen, hasrecently been deployed by usin fieldstudies with A. humilislarvae to testa numberof factorsthat might influence the typesof recruitmentpatterns exhibited by this coralspecies on thereefs of Bonaire.These include:availability of morphogen, behavioral response of larvae to orientation of substrate, effectof larvaltime in theplankton on requirement and stringency of recognition, and effect of depthon activity of themorphogen aswell as on post-recruitment predation and survival.

SIGNALS, RECEPTORS, TRANSDUCERS AND GENES CONTROLLING SUBSTRATUM-SPECIFICMETAMORPHOSIS: LARVAL ECOLOGY AND PRACTICALAPPLICATIONS. D.E. Morse and A.N.C. Morse, Marine Biotechnology Center,Marine Science Institute, University of California, Santa Barbara, CA 93106,USA Planktoniclarvae of benthicspecies from 3 phyla the coral, Agaricia; the mollusc, Haliotis;and the polychaete, Phragmatopoma! recognize specific signal molecules from the environmentthat induce substratum-specific settlement and metamorphosis. Wehave found that recognitionof these chemical cues plays a majorrole in determiningthe distribution of recruits inthe natural environment. InHaliotis larvae, these processes arecontrolled by2 convergent chemosensorypathways thatrespond to2 differentclasses ofchemical signals, each recognized bya distinctreceptor. To resolve the relative contributions ofchemosensory recognition and otherenvironmental factors that controlrecruitment of Agariciahumilis induced to metamorphosebyglycosaminoglycans associated with cell walls of therecruiting crustose red algae!,we are using a morphogen-basedchemical "flypaper" containing the purified inducer boundtoan artificial substratum. Practical applications ofsuch studies are seen in2 areas:! Useof larvalsignal molecule control points can increase profitability and yield in aquaculture aslarval settlement isfar more sensitive topollutants than is simple survival, providing State andFederal agencies with new bioassays thatare more reliable, less expensive andecologically moresignificant than those previously based on mortality. ! Becausethesignals, receptors, transducersandgenes controlling larval settlement areclosely related to thosecontrolling cell function,neuronal activity and development in humans, they may provide the basis for new therapeuticand diagnostic agentsfor human medicine.

36 EYE DESIGN, VISION AND INVISIBILITY IN PLANKTONIC INVERTEBRATES. D.-E. Nilsson, Departmentof Zoology, University of Lund, Helgonavagen3, S-223 62 Lund, Sweden

Unlike the continuous and extendednature of terrestrial visual environments, the visual world of planktonic animals consistsprimarily of point objects, either bioluminescentsources contrastingagainst a dark backgroundor dark silhouettesseen against a bright backgroundof downwelling day-light. The eye designsof planktonic invertebratesreveal a numberof unusual specializationsexploiting this uniquevisual 'environment.Some of the more interestingcases are the large cameraeyes of alciopid polychaetes,the tubular eyesof somesquid, the scanningeyes of heteropod molluscs and various copepod crustaceans,the parabolic mirror eyes of the ostracodcrustacean Gigantocypris, and the divided compoundeyes of euphausiidand hyperiid crustaceans.Many of theseeyes provide large-field general vision, which is useful in bright shallow habitatsand suits the detectionof bioluminescenceat any depth. Other eyeshave narrow visual fields specialized for spotting objects against the dim downwelling day-light at considerabledepths downto 700 m!. A relationbetween depth and eye design is particularly evident in somecrustaceans such as euphausiids and hyperiid amphipods:the deeperthe habitat, the more of the eye is concernedwith upward vision. The presenceof upward-looking predatorsis the obvious reasonfor severaltypes of camouflageto reduce the size or contrast of the body silhouette. General transparencyis one such adaptationwhich even involves a special type of transparent compoundeye in severalcrustacean groups.

SENSORY INPUTS TO THE NEURONS UNDERLYING PREY CAPTURE IN THE PTEROPOD MOLLUSC, CLIONE LIMACINA. T.P. Norekian, Departmentof Zoology, Arizona State University, Tempe, AZ 85287-1501,USA

The predatory pteropod mollusc Clione limacina is an extremefeeding specialistwhich feedsonly on shelledpteropods from the genusLimacina. Direct contactwith Limacina initiates a prey capture behavior which consistsof an explosive extrusion of buccal cones, specialized structuresthat are usedto catchthe prey, andacceleration of swimmingwith frequentturning and looping aroundthe placewhere Limacina was contacted. A systemof neuronswhich controls different componentsof prey capture behavior in Clione has been identified in the cerebralganglia. Tactile andchemical stimuli, which initiate feedingbehavior in intact animals, produceexcitatory inputs to theseneurons. Tactileinputs from the anteriorpart of the head producestrong, phasic activation of theneurons and appear to beof particularimportance since only direct mechanicalcontact with the prey initiates prey capturereactions. However, chemosensoryinputs also are believed to be importantfor chemicalrecognition of theprey. Purechemical stimuli without the mechanosensory component Limacina juice wasused in these experiments!induce a tonic,prolonged activation of theneurons and appear to bevery specific.

37 CONFIRMATIONAND MEASUREMENTOF BIOLUMINESCENCEOF THE PELAGICSHRIMP, SERGIA LUCENS. M. Omori',H. Fukami,and M.I. Latz. 'DepartmentofAquatic Biosciences, TokyoUniversity ofFisheres, 4-5-7, Konan, Minato-ku, Tokyo108, Japan, ~Marine Biology Research Division, Scripps Institution ofOceanography, Universityof California,San Diego, La Jolla, CA 92093-0202,USA Thisinitial study is thefirst direct confirmation of bioluminescence in Sergia lucens. Lightemission probably originates from the numerous, more than 160, dermal photophores. Lightemission was measured bya photon-countingphotomultiplier with a computerizeddata acquisitionsystem and a TVcamera equipped with an image intensifier and VTR. Light emissionwas directed downward from the ventral surface of thebody, and occurred overall as a dimcontinuous glow. Themaximum intensity was measured in female with matured ovaries being1.09x10 quanta/sec. This value was nearly equal to thatof downwellingillumination between250 and 300 m depthof thesea during daytime, suggesting that the bioluminescence maybe usedin countershadingthe body. Additionalresearch is neededto confirmwhether bioluminescenceis involved in swarmingbehavior of thiscommercially important species.

SOUNDDETECTION BY FISHES.A.N. Popper, Department ofZoology, University of Maryland, College Park, MD 20742, USA

Bioacousticsstudies have demonstrated that manyspecies of fish usesound for communication.Sounds are used in a varietyofbehavioral contexts, and provide long-distance, rapid and directional information in all water conditions. Sounddetection capabilities have been studied behaviorally in about 80 species and fishes canbe divided into two groups groups hearing generalists andhearing specialists. Hearing generalistsmost often detect sounds from below 50 Hz to about 500 to 800 Hz, while hearing specialistsoften detect signals from below 50 Hz to over3,000 Hz. Hearingsensitivity in specialistsalso exceeds that of generalists.Hearing specialists always have some structures associatedwiththe auditory system that enhance sound detection capabilities. Significantly, specialistsarefound in manyfish taxonomic groups, suggesting thatsimilar specializations have arisen multiple times in fish evolution. Thistalk will considerthe range of hearingcapabilities found among fishes and examine someof the characteristics of the peripheral auditory system that are found in hearing generalists andspecialists. [Work supported by ONR,NASA, and NIH]

38 CHEMICAL BASIS FOR PREY SELECTION IN A PELAGIC CNIDARIAN. J.E.Purcell and P.A.V. Anderson, University Maryland, Horn Point Environmental Laboratory, Cambridge,MD 21613; University Florida, Whitney Laboratory, St. Augustine, FL 32086, USA

Dietaryanalyses have showed that most siphonophores consume primarily crustacean zooplankton,but that Physalia physalis, the Portuguese man of war,consumes mostly fish and fishlarvae. Intracellular recordings from nematocyst-containing cellsin small pieces ofPhysalia tentacleswere used to quantify the electrical responses tochemical stimulation. Aqueous stimuli seawatercontrol, fish mucusextract, and 10 nM 1 mM aminoacids, nucleosides, monosaccharides!weredelivered upstream of the tissue by a 0.1ml volHPLC rotary loop injector.Seawater caused noresponse. The fish mucus extract produced 1-13 depolarizing spikes0 mVmax. amplitude!. Only the ,000 MWfraction was stimulatory. The various chemical >100 nM! caused 1-6 spikes of loweramplitude than the mucus extract. Aspartic aminoacid, histidine,and serine together comprised 60% of theamino acids in the fish mucus. Weconclude that prey capture in Physulia. ismediated bychemical stimuli from the prey, which mayaffect nematocystdischarge. Funded by NSF grant BNS-9011030.

MEMORYFOR FISH KAIROMONE IN DAPHNIA.J. Ringelbergand E. vanGool, Departmentof Aquatic Ecology, University of Amsterdam,Kruislaan 320, 1098 Amsterdam, The Netherlands

A chemical,mediated by visuallypredating fish, enhances phototactic reactivity to relativechanges in light intensity in Daphnia.In theepilimnion of LakeMaarsseveen, this kairomoneispresent when large shoals ofjuvenile perch Perca fluviati lis! roam the open water zone.At dawn,when relative increases in light intensity are maximum, the sensitizing effect leadsto extensivedownward movements out of the well-litpredation zone and into the hypolimnion.Although no kairomone is present atthis greater depth, an equally strong positivelyphototactic reaction brings the daphnids back into the epilimnion at dusk. Also, migrationcontinues for somedays after the juvenile perch have dispersed into the littoral zone. Theseobservations suggest that the sensitizing effect is preservedfor sometime. Indeed, experimentsrevealed that sensitivity gradually diminishes over a periodof 4-5days.

39 MORPHOLOGY OF WING MECHANORECEPTORSINVOLVED IN THE WING RETRACTIONREFLEX OF THE PTEROPODMOLLUSC CLIONE LIMACINA. R.A.Satterlie, M. Lagro,M. Titus,S. Jordan and K. Robertson,Arizona State University, Tempe, AZ 85287-1501,USA

Tactilestimulation of thewings parapodia!of activelyswimming Clione results in inhibitionof swimmingand retraction of the wings. Electrophysiological evidence suggests that wingmechanoreceptors havecentral cell bodies and wide innervation fields in theipsilateral wing.Scanning electron microscopy ofexpanded wings reveal ciliary cone processes arranged ina patternthat is similar to the electrophysiologically-determined innervationfields of wing mechanoreceptors.Transmission electron microscopy suggests that the ciliary cone structures areterminal processes of neuron-like cells. Three-dimensional reconstructions of serially- sectionedterminal processes indicate that cell bodies are not found in thewing epithelium or immediatelyunder the epithelium, further supporting thenotion that the wing mechanoreceptors do have central cell bodies.

RECEPTIONAND PRODUCTIONOF HYDRODYNAMICSTIMULI IN CRAYFISH AND SNAPPINGSHRIMP. B. Schmitz,Fakultat fur Biologic,Universitat Konstanz, Postfach5560, D-78434 Konstanz, Germany Eachorganism moving under water produces hydrodynamic stimuli. Red swamp crayfish Procambarusclarkii!, which are predominantly active at night, analyze these water movements to detectand localize predators, prey and conspecifics. During development thebehavioral responsestowards small swimming fish change from escape or roughstimulus lateralization in juvenilecrayfish toaccurate orientational responses andprey capture in adults. The sensory basesofthese changes areanalyzed studying thedevelopment ofhydrodynamic telson receptors, oftheir central projections, andthe connectivity between these hair sensilla andmechanosensory interneuronsin the terminal ganglion. Marine snapping shrimp e.g. Alpheus heterochaelis! areable to producea loudsnap as well as a fastwater jet by rapidlyclosing a specialized snapperclaw. The time of clawclosure isbelow 750 microseconds asrevealed by highspeed videoanalysis and optoelectrical measurements. Theacoustic and hydrodynamic signals, which areused in defense against predators andconspecific intruders, butmay also serve to stun prey organisms,areanalyzed with respect to amplitude,temporal, spatial and spectral parameters. Whileauditory receptors aremissing in snapping shrimp a largenumber of hair sensilla, and thuspotential hydrodynamic receptors, isrevealed byscanning electron microscopy.

40 SURFACE GLYCOPROTEINS SERVE AS CONTACT MATE RECOGNITION PHEROMONES IN ROTIFERS. T.W. Snell and R. Rico-Martinez, School of Biology, Georgia Tech, Atlanta, GA 30332-0230,USA

Pheromonal regulation of invertebrate reproduction influences several important ecological processeslike locating conspecifics, recognizing them as potential mates, and transferring sperm. For commonzooplankters like copepodsand rotifers, behavioralevidence has suggestedthe existenceof sex pheromones,but none hasbeen isolatedand characterized. We describe a 29 kD glycoprotein gp29! on the surface of females of the marine rotifer Brachionusplicatilis that actsas a contactmating pheromone. This glycoprotein is glycosylated with oligosaccharidescontaining N-acetylglucosamine, mannose, and fucoseresidues and these oligosaccharidesare necessaryfor male recognition of females. Binding of purified gp29 to male receptors reduced mating attemptsby 93%. An antibody to gp29 bound to females, reducing male mating attemptsby 86%. When purified gp29 is bound to sepharosebeads, it is sufficient to elicit male matingbehavior. Comparisonof gp29 amongB. plicatilis populations suggests differentiation at the species level. Lectin binding studies with copepods and cladoceranssuggest that there are surfaceglycoproteins present in thesegroups that could serve as contact mating pheromones.

EXCITABILITY PROPERTIES OF EPITHELIA AND NEURONS IN POLYORCHIS HYDROZOA!: THEIR RELEVANCE TO BEHAVIOR. A.N. Spencer, N. Grigoriev and J. Przysiezniak. University of Alberta and Bamfield Marine Station, Bamfield, BC., VOR1BO, Canada

In this talk I will compareand contrast electrical excitability in epithelia and neurons. The characteristics of the demonstratedproperties are a combination of conventional and specializedfeatures. Surprisingly, all tissuesin hydromedusaeare capableof conductingaction potentials. Both epithelial layers, whether they are pure pavementepithelium or epithelio- muscular cells, are excitable. These epithelia are capable of behavioral habituation. Action potentialsare initiated by touch and propagatethrough epithelial sheetsat velocities that depend on the firing frequency. Using both extracellularrecording from excisedtissue and patch-clamp recording of cultured cells it can be shown that the conduction velocity decrease that is seen during repetitive stimulation is calcium dependent. The firing propertiesof 3 different neuronaltypes are very different and are related to their particular functions. For example"0" neuronswithin the ocellar pathwayproduce graded, oscillatory action potentialsthat are modulatedby light; "B" neurons,which are smoothmuscle motor neurons, produce simple, all-or-none action potentials, and SMNs, which are the motor neuronscontrolling swimming, have variable duration action potentials. For all thesecells we are trying to determine which suitesof channel proteins have been selectedto produce each characteristicexcitability property. Preliminary electrophysiologicaland molecularresults will be discussed.

41 SENSORY POTENTIAL IN CILIATEDZOOPLANKTON: STRUCTURAL AND BEHAVIORALASPECTS OFDIET SELECTION IN ROTIFERS. P.L. Starkweather, DepartmentofBiological Sciences andLimnological Research Center, University ofNevada, Las Vegas, NV 89154, USA Rotifersexhibit a widerange offeeding behaviors which differ in response tochanges in nutritionalenvironment oravailability ofprey. In particular, many suspension-feeding branchionidsmodify food collection when they encounter foods of differingsize, chemical contentoravailable density. Ploimate predatory species differentiate between conspecific prey of distinctancestry. These observations pointto a substantialarray of mechano-and chemosensorymodalities, ofwhich most, if not all, are based onciliary structures ofthe corona. Thevarious cilia, ciliary bundles andcirri appear tobe coordinated through a series ofnerves andmuscles which permit remarkably complicated behaviors when the animals contact individual foodcells. Judging from measurements of near-coronal flows, all cilia and compound cilia cirri!of the rotifer corona operate inan environment characterized byReynolds Numbers Re! between10 and10 . All remoteor "contact" sensory reception andresulting behavioral responsesare therefore constrained to occurin laminar,viscous fluid flows.

FIELDAND LABORATORYOBSERVATIONS OF THE CUBOZOAN TRIPEDALIA CYSTOPHORA:IMPLICATIONS REGARDING VISION. S.E. Stewart, TheUniversity of TexasMarine Science Institute, Port Aransas, TX 78373,USA Theadult medusa Tripedalia cystophora issmall -1.0 cm bell height! and occupies a coastalmangrove habitat in southwesternPuerto Rico. Likeother members of the Class Cubozoa,T.cystophora possesses multiple complex eyes as well as pigment-cup ocelli. Field observationsindicateno apparent rolefor the complex eyesin locating mates, other conspecifics orprey. Laboratory experiments confirm a positive phototaxis, butno chemotaxis withregard toprey swarms cyclopoid copepods ofGenus Oithona!. Research inprogress asof August 1994concerns thepossibility ofa feedingorother role of the complex eyesin the bell interior, forthe complex eyes are oriented inward and have a structureconducive tovision within a 1cm range.The presentation will cover aspects of the entire study.

42 INFORMATION, INFORMATION, INFORMATION! SEEING VON UEXKULL'S "UMWELT" OF PLANKTONIC CRUSTACEANS AND THE ANIMAL'S REACTIONS TOWARDS IT. J.R. Strickler, University of Wisconsin, Milwaukee, WI 53204, USA

Planktonic crustaceanslive within a fluid environment at spatial and temporal scales unfamiliar to humans. For the past25 yearsI tried to elucidatethe "Umwelt" of theseanimals usingnon-intrusive optical techniques. The requirements for choosinga specificoptical pathway were stringent: high temporal msec!and spatial pm! resolutions,large dynamic ranges msec to hours, pm to 10 cm!, visualization of differences in optical density, three-dimensional observations,and all in the largest vesselpossible. In a videoI will show and explain a seriesof techniques,novel and old ones, addressing someof the following questions: Are algae touchedby the setaeof the catching animal? Do prey changetheir swimming pattern in the presenceof predators? How large is the encounter radius of a predator? How do animals react to bioturbulence? Can planktonic crustaceans perceivespatial changes in density,viscosity, salinity, and temperatureof their surroundwater?

THE DELAY OF METAMORPHOSIS IN DECAPOD LARVAE DUE TO SUBSTRATE AND CONSPECIFIC CUES. I. Walter and K. Anger, Biologische Anstalt Helgoland, 27493 Helgoland, Germany

Benthic decapods often still possessconsiderable mobility after metamorphosis. Nevertheless,selection of an appropriatehabitat for benthic life by the planktonic larva before metamorphosismight be of advantage,especially if a speciesis restricted to a very specific habitat. In this study,three decapod species were tested for theirability to delaymetamorphosis in the presenceor absenceof cuesfrom the substrateor from adult conspecificsas "markers" for an appropriatehabitat. Chasmagnathusgranulata and Sesarmacuracaoense are restricted to specifichabitats muddy substratesof salt marshesand lagoons,and mangroveswamps respectively. In the laboratory,megalopae of thesespecies performed metamorphosis significantly earlier in the rpesenceof adult femalesthan without substrateor conspecifics.C. granulata megalopaereacted in the sameway to the presenceof mud and sand. The marine speidercrab Hyas araneus is less specific but shows a slight preferencefor filamentous algal substrates. Megalopaeof this specieswent through metamorphosis signficantly earlier when red algaewere offeredas a substrate.In all cases,the cuesare likely to be chemicalas artificial substratesof equalparticle size and texture had no effecton theduration of the megalopastage as compared to control groupswith no substrate.Our experimentsalso indicatedthat the megalopaeof differentspecies may be responsiveto habitatcues at differenttimes during their development.

43 MORPHOLOGICALSTUDIES OF MECHANO-AND CHEMORECEPTIVESETAE IN THE FIRSTANTENNA OF A CALANOIDCOPEPOD. T. Weatherbyand P.H. Lenz,Biological Electron Microscope Facility and Bekesy Laboratory ofNeurobiology, Pacific BiomedicalResearch Center, University of Hawaii,Honolulu, HI 96822USA Thefirst antennae of calanoid copepods bear mechanoreceptive setaeon their distal tips whichphysiologically and behaviorally demonstrate exceptional performance characteristics comparedtomechanoreceptors inbenthic crustaceans Yenet al. J. PlanktonRes. 14: 495 [1992]; Herren,Lenz, and Hartline, this volume!. In addition,the first antennae bear at least three types of receptors.We made an ultrastructural TEM study of thesereceptors. Thelong spiniform setae of thedistal tip whichpresumably give rise to thegiant axons reportedbyYen et al. 1992loc. cit.! show ultrastructural characteristics ofpure mechanoreceptors, beingcharacterized byan exceptional number and density of dense-coremicrotubules upto 2000 per sensorydendrite!. The spiniform setae located along the antennalshaft possess two mechanoreceptorseach,and in addition, two chemoreceptors, thindendrites ofwhich project well intothe setal shaft. The setae readily stain with methylene blue, and this dye travels in timeinto theputative chemosensory somata located near the bases ofthe setae. These setae, unlike the pure mechanoreceptivesetaeof thedistal tip, possess terminal pores which appear to giveaccess to the externalmedium. Their characteristics arecompatible with their subserving a gustatory function contactchemo + mechano!.Asthetascs along the antennal shaft are characterzed bythin cuticular wallsand many fine dendrites with small numbers of microtubules ineach. These setae readily stainwith azocarmine,but the dye does not readily penetrate to the cell bodies. SupportedbyNSF OCE 89-18019 and a grantfrom the UH President's Development Fund.

RECORDINGAND ANALYSISOF THE TURBULENTPROPULSION JET OF EUPHAUSIIDSHRIMP CRUSTACEA!. K.Wiese, Zoologisches Institut und Zoologisches Museumder Universitat, Martin Luther King Platz 3, 20146Hamburg, Germany Thenotion that turbulent flow generated byswimming shrimp constitutes a signal used generallyin intraspeciescommunication and in recruitmentto schoolsand in controlof formationswimming ineuphausiids hasbeen tested intetheredly swimming Euphausia superba, Meganyctiphanesnorvegica, and Leander udspersus. Recording of the propulsion jetwas first doneby pressure sensitive microphone, laterusing hot wire anemometry. Detailed FFT spectra ofthe signals obtained show a basefrequency specific for the species of shrimp together with 2-4harmonics atmultiples ofbase frequency. Broadband background noiseas revealed by analysisofa signalobtained byidentical recording technique fromturbulent flow generated by a modelship propeller, shows strong contribution tothe spectrum atlow frequencies, weak contributionat high frequencies, is absent in the turbulent flow signals produced bythe measuredswimming shrimp. The flow sensor within the antennules of Euphausia, a proprioceptivescolopal organ controlling movement inthe basal hinge of the ventrally directed flagella,matches allrequirements connected withreception offlow velocity, flow direction and analysisof spectralcontent of theturbulent flow signal.

NATURALINGESTION RATES OF MARINECALANOID COPEPODS IN WATERS

44 NATURAL INGESTION RATES OF MARINE CALANOID COPEPODSIN WATERS AROUNDTHE NANSHAISLANDS OF THE SOUTHCHINA SEA. C.K.Wong, Q.C.Chen, and L.M. Huang, 'Department of Biology, The Chinese University of Hong Kong,Shatin, Hong Kong, and zSouth China Sea Institute of Oceanology,Guangzhou, The People's Republic of China

Thegut fluorescencetechnique was used to estimatethe grazingrate of calanoid copepodsin tropical waters around the Nansha Islands of theSouth China Sea. Chlorophyll a concentrationswithin the upper 100 m ofthe water column ranged from 0.19 to 1.0mg m Numericallydominant calanoid copepod species in thestudy area included Acartia erylhraea, Undinula vulgaris and Rhincalanus cornutus. Gut pigment contents were measured for eighteen species.Ingestion rates were determined from measurements of gut pigment content and gut evacuationrate. Pronounceddiel and spatial variations in ingestionrate were observed in some species.In specieswith sufficient data for comparison,ingestion rates were usually higher duringthe night and evening than during the day. Average ingestion rate for calanoid copepods was202.6 ng Chl a animal' day '. Communitygrazing rate, estimated from average ingestion rateand average copepod abundance, showed that .5% of totalchlorophyll a standingstock wasgrazed by calanoidcopepods each day.

MATE TRACKING IN COPEPODS: PHEROMONES OR SPECIES-SPECIFIC WAKES?J. Yen,S. Colin,M. Doall,P. Moore',A. Okubo,and J.R. Strickler, Marine SciencesResearch Center, State University, ofNew York, Stony Brook, NY 11794-5000, USA; 'Departmentof Biological Sciences, Bowling Green State University, Bowling Green, OH 43403,USA; Centerfor GreatLakes Studies, University of Wisconsin,Milwaukee, WI 53208, USA

Animportant behavioral response of copepods in additionto prey capture and predator avoidance!ismating. Here we present three dimensional tracking ofpaths taken by the pelagic marinecopepod, Temora longicornis, while seeking and grabbing mates in thedark. Thetrack of themale precisely follows the track of thefemale, initiated atdistances greater than 20 body lengthsapart and separated bytimes of morethan 5 sec.Through analyses of the strength of thesignal generated bythe female vs. the signal strength atthe point when the male crosses her path,we wish to ascertainthe potential importance of thefluid mechanicalvs. chemicalcue as a trigger of mating behavior.

45 CHEMOSENSORY ECOLOGY OF MARINE LARVAE: BENTHIC-PELAGIC COUPLING.R.K. Zimmer-Faust,University of SouthCarolina, Columbia, SC 29208, USA

Habitatcolonization by planktoniclarvae is a dominantfactor controlling population dynamicsof mostbenthic invertebrates. Chemical properties of marineenvironments are importantcues used by larvaeto selectsettlement sites. To a largeextent, studies on settlement havebeen limited by a lackof technologyfor rapidlyassessing larval behavior. We have overcomethis difficulty by applyingcomputer-video motion analysis to non-invasivelytrack the pathsmade by free-swimmingplanktonic larvae. Our resultsindicate chemically-mediated changesin swimmingbehavior demonstrating a clear association between application of a dissolvedchemical stimulus and rapid behavioralresponse by oysterlarvae. Behavioral responsesdiffer for metabolitesreleased by adult conspecificsand exudatesreleased by microalgalprey. Chemoreceptivebehavior suggestive of larval settlementis thereforenot a generalresponse evoked by all novelorganic compounds. Our field and laboratory findings are consistentin identifyinglow molecularweight peptides with arginineat the C-terminalas the natural,water-soluble cues inducing oyster settlement. Cue production may be linked to general metabolicprocessing or to digestion of proteinacquired by benthic heterotrophs through dietary sources.Remarkably, in estuarineenvironments, such conditions are most commonly met by theaggregations of postmetamorphic oysters and their associated communities on oysterreefs.

46 PARTICIPANT LIST

Dr. Julie W. Ambler, Departmentof Dr. John Arnold, Pacific Biomedical Biology, Millersville University, P.O. Box Research Center, University of Hawaii, 1002, Millersville, PA 17551, USA Honolulu, HI 96822, USA jw ambler! daffy.millersv.edu

Dr. Jelle Atema, Boston University Mr. AlexanderB. Bochdansky, Marine Program, Marine Biological Ocean Science Centre, Memorial Laboratory, Woods Hole, MA 02543, University of Newfoundland, St. John' s, USA Newfoundland, A1C 5S7, Canada bochdanomorgan.ucs. mun.ca

Dr. SteveBollens, Biology Dr. Horst Bleckmann,Zoologisches Department,Woods Hole Oceanographic Institut der Universitat Bonn, Institute, Woods Hole, MA 02543, USA Poppelsdorfer SchloP, D-53115 Bonn, bollens.cole.whoi. edu Germany

Dr. Geoff Boxshall, The Natural Dr. ThomasBreithaupt, Fakultat fiir History Museum, Cromwell Road, Biologic. Universitat Konstanz, Postfach London SW7 5BD, UK 5560 M618!, D-78434 Konstanz, g. box shal1tNnhm.ic. ac. uk Germany thomas. breithaupt!uni. konstanz. de

Mr. Matthew Brewer, University of Dr. Harold Bright, Molecular, Cell Wisconsin, 446 Birge Hall, 430 Lincoln and Environmental Biology, Office of Dr., Madison, WI 53706, USA Naval Research, Ballston Tower One, 800 mbrewerl mace.wise. edu N. Quincy St., Arlington, VA 22217-5660

Dr. Howard I. Browman, Maurice- Dr. Bernd-Ulrich Budelmann, Marine Lamontagne Institute, Fisheries and Biomedical Institute, University of Texas Oceans Canada, P.O. Box 1000, Mont- Medical Branch, Galveston, TX 77555- Joli, Quebec, Canada G5H 3Z4, 0863, USA h browmanoimll.ind.dfo.ca budelmannombian. utmb. edu

Dr. TheodoreH. Bullock, Scripps Dr. Marie H. Bundy, Great Lakes Institution of Oceanography,University EnvironmentalResearch Laboratory, of California, San Diego, La Jolla, CA NOAA, 2205 Commonwealth Blvd., Ann 92093, USA Arbor, MI 48105, USA' tbullockoucsd. bitnet bundyoglerl. noaa.gov

Dr. Edward J. Buskey, Marine Science Dr. Nancy M. Butler, FlatheadLake Institute, The University of Texas at Biological Station, The University of Austin, Port Aransas,TX 78373-1267, Montana, 311 Biostation Lane, Poison, USA MT 59860, USA buskeytNutmsi. zo. utexas. edu nbutler.selway.umt.edu

Dr. James Case, Marine Science Dr. Jack H. Costello, Departmentof Institute, University of California, Santa Biology, ProvidenceCollege, Providence, Barbara, Santa Barbara, CA 93106, RI 02918-0001, USA USA costello!providence. edu case!omni. ucsb.edu

47 Dr. ThomasW. Cronin,Department of Dr. JackDavidson, Sea Grant College BiologicalSciences, University of Program, School of ocean and Earth Maryland Baltimore County, 5401 Scienceand Technology, University of Wilkens Ave., Baltimore, MD 21228- Hawaii, 1000 Pope Road, Honolulu, HI 5398, USA 96822, USA cronin!umbc7.umbc.edu

Dr. Don Deihel,Ocean Science Centre, Dr. Luc De Meester,Universiteit Gent, Memorial University, St. John's, Laboratoryof AnimalEcology, K.L. Newfoundland, A1C 5S7, Canada Ledeganckstraat35, B-9000 Gent, [email protected]. mun.ca Belgium Luc. DeMeesteorug.ac.be

Ms. Lisa Dilling, Departmentof Mr. Michael Doall, Marine Science BiologicalSciences, University of ResearchCenter, State University of New California, SantaBarbara, CA 93106, York at Stony Brook, Stony Brook, NY USA 11794-5000, USA dillingOlifesci. lscf. ucsb.edu

Dr. StanleyL Dodson,Department of Dr. ToneFalkenhaug, University of Zoology, University of Wisconsin, 117 Tromsa,The NorwegianCollege of West JohnsonStreet, Madison, WI FisheryScience, 9037 Tromse, Norway 53706, USA tonef!nfh.uit. no dodsonsomacc. wise. edu

Dr. LyndaFarley, Boston University DaveFeatherstone, Bek6sy Marine Program, Woods Hole, MA Laboratory of Neurobiology, P.B.R.C., 02543, USA University of Hawaii, 1993 East-West farley!biology.bu. edu Road, Honolulu, HI 96822-2359, USA davefowana. pbrc.hawaii. edu

Dr. Richard Forward, Jr., Duke DavidM. Fields,State University of University Marine Laboratory, Beaufort, New York, Stony Brook, c/oNELH, P.O. NC 28516-9721, Box 1749, Kailua-Kona, HI 96745, USA r forward!acpub.duke. edu fields!uhunix.uhcc. hawaii.edu

Dr. Tammy Frank, Harbor Branch Ms. Melissa Frey, Marine Sciences Oceanographic Institution, 5600 U.S. 1 ResearchCenter, State University of New North, Fort Pierce, FL 34946, USA York at StonyBrook, NY 11794-5000, harbofraoclass.org USA

Dr. CharlesGait, Biology Ms. JasmineGokcen, Department of Department,California State University, Ecology, Evolution and Behavior, Long Beach, CA 90840-3702, USA Universityof Minnesota,1987 Upper gait!csu lb. edu Buford Circle, St. Paul, MN 55108, USA gokc0001@gold. tc. umn. edu

Mr. Erik van Gool, Departmentof Dr. Wulf Greve,Biologische Anstalt AquaticEcology, University of Helgoland,Zentrale Hamburg, Amsterdam, Kruislaan 320, 1098 SM Notkestrag31, 22607Hamburg, Amsterdam, The Netherlands Germany

48 Dr. Michael Hadfield, Kewalo Marine Ms. Peggy Hamner, Department of Laboratory, P.B.R.C., University of Biology, University of California at Los Hawaii, Honolulu, HI 96822, USA. Angeles, Los Angeles, CA 90024-1606, had fieldouhunix. uhcc. hawaii. edu USA hamnerobiology.li fesci.ucla.edu

Dr. William M. Hamner, Department Mr. Lars J. Hansson,Goteborgs of Biology, University of California at Universitet, Marina forskiningstationen Los Angeles, Los Angeles, CA 90024- vid, Kristineberg, S-450 34 1606, USA Fiskebackskil, Sweden hamnero biology. li fesci. ucla. edu

Dr. Daniel K. Hartline, Bekesy Ms. Karla B. Heidelberg,Horn Point Laboratory of Neurobiology, P.B.R.C., Environmental Laboratory, University of University of Hawaii, 1993 East-West Maryland, Box 775, Cambridge, MD Road, Honolulu, HI 96822-2359, USA 21613, USA danhouhunix. uhcc. hawaii. edu karla b heidelbergoumail.umd.edu

Ms. Christen Herren, Department of Dr. Mimi A.R. Koehl, Departmentof Biology, University of South Carolina, Integrative Biology, University of Columbia, SC 29208, USA California at Berkeley, Berkeley, CA 94720, USA cnidariaoviolet.berkeley.edu

Dr. Petter Larsson, Museum of Dr. Michael L Latz, Marine Biology Zoology, University of Bergen, Museplass ResearchDivision 0202, Scripps 3, N-5007 Bergen, Norway Institution of Oceanography,University petla!oscar.bbb. no of California, San Diego, La Jolla, CA 92093, USA mlatzouscd. edu

Dr. Petra H. Lenz, BekesyLaboratory Dr. Darcy J. Lonsdale, Marine of Neurobiology, P.B.R.C., University of Sciences Research Center, State Hawaii, 1993 East-West Road, Honolulu, University of New York, Stony Brook, HI 96822-2359, USA NY 11794-5000, USA petraowana.pbrc.hawaii.edu d1onsdaleoccmail. sunysb. edu

Dr. GeorgeO. Mackie, Departmentof Dr. David L. Macmillan, Department Biology, University of Victoria, Victoria, of Zoology, University of Melbourne, BC, V8W 2Y2, Canada Parkville, Victoria, 3052' Australia mackouvvm. uvic. ca zoo macoariel. ucs. un imelb. ed u. au

Dr. Laurence P. Madin, Woods Hole Dr. N. Justin Marshall, Sussex Centre Oceanographic Institution, Woods Hole, for Neuroscience,School of Biological MA 02543, USA [email protected] Sciences,University of Sussex,Brighton BN1 9QG, UK

Dr. GeorgeMatsumoto, Flinders Dr. Florence McAlary, Wrigley University of South Australia, Marine ScienceCenter, University of Department of Biological Sciences, GPO Southern California, P.O. Box 398, Box 2100, Adelaide, South Australia, Avalon, CA 90704, USA 5001, Australia bigimocc. flinders. edu. au

49 Dr. WilliamMcFarland, Wrigley MarineScience Center, University of Dr. DeForestMellon, Jr., SouthernCalifornia, Avalon, CA 90704, Departmentof Biology,Gilmer Hall, USA Universityof Virginia,Charlottesville, VA 22903,USA DM6D.virginia.edu Dr. AileenN. C. Morse,Marine Dr. Dan E. Morse,Marine Science BiotechnologyCenter, Marine Science Institute,University of California,Santa Institute,University of California,Santa Barbara,CA 93106-6150,USA Barbara,CA 93106,USA d morsetglifesci.Iscf.ucsb.edu a morse!lifesci.lscf.ucsb.edu

Dr. TigranNorekian, Department of Zoology,Arizona State University, Dr. Dan-E.Nilsson, Department of Tempe,AZ 85287-1501,USA Zoology,University of Lund, attpn@asuvm. inre.asu.edu Helgonavagen3, S-22362 Lund,Sweden zdan@gemini. Idc. lu. se

Prof.Makoto Omori, Department of AquaticBiosciences, Tokyo University of Dr. ArthurN. Popper,Department of Fisheres,4-5-7, Konan, Minato-ku, Biology,University of Maryland,College Park, MD 20742, USA Tokyo 108, Japan makomori!tokyo-u-fish.ac.jp ap17tgumaih umd.edu

Dr. JennyE. Purcell,Horn Point EnvironmentalLabs, University of Dr. JoopRingelberg, Universisteit van Maryland,P.O. Box 775, Cambridge, Amsterdam,Sectie Aquatische, MD 21613, USA Oecologie/Oecotoxicologie,Kruislaan 320, 1098SM Amsterdam,The purcelltgihpek umd. edu [email protected] Dr. RichardSatterlie, Department of Zoology,Arizona State University, Dr. BarbaraSchmitz, Fachbereich Tempe, AZ 85287, USA Biologic,Universitat Konstanz, Postfach 5560 M618!,D-78434 Konstanz, aaras!asu v m. in re. asu. ed u Germany bimarkl!nyx. uni-konstanz.de Dr. KennethP. Sebens,Department of Zoology,University of Maryland,College Dr. TerryW. Snell,School of Biology, Park, MD 20742, USA GeorgiaInstitute of Technology,Atlanta GA 30332-0230,USA KS95@umail. umd. edu terry. snell!biology. gatech.edu Dr. AndrewSpencer, Bamfield Marine Station,Bamfield, BC., VORIBO, Dr. OleB. Stabell,University of Canada Tremse,The Norwegian College of andrew.spencer@ual berta. ca FisheryScience, 9037 Tromse, Norway [email protected]

Dr. PeterL. Starkweather, Departmentof BiologicalScience, Dr. DeborahK. Steinberg,Institute of Universityof Nevada,4505 Maryland MarineSciences, University of California,Santa Cruz, CA 95064,USA Parkway,Las Vegas, NV 89154,USA steinber!biology.ucsc. edu peters!nevada. edu

50 Mr. Scott Stewart, Marine Science Dr. J. Rudi Strickler, Center for Institute, The University of Texas at Great Lakes Studies,University of Austin, P.O. Box 1267, Port Aransas, TX Wisconsin, 600 E. Greenfield Avenue, 78373-1267, USA Milwaukee, WI 53204-2944, USA stewart!utmsi. zo. utexas. edu

Ms. Cynthia Suchman, Graduate Dr. Barbara Sullivan, Graduate School of Oceanography, University of School of Oceanography, University of Rhode Island, Narragansett, RI 02882, Rhode Island, Narragansett,RI 02882, USA USA csuchman!gsosun1. gso. uri.edu bsul1!gsosun 1.gso.uri.edu

Ms. Ismeni Walter, Meeresstation, Ms. Tina M. Weatherby, Biological Meeresokologisches Labor., 24783 Electron MicroscopeFacility, Pacific Helgoland, Germany Biomedical ResearchCenter, University of Hawaii, 1993 East-West Road, Honolulu, HI 96822, USA tina!wana. pbrc. hawaii. edu

Dr. Konrad Wiese, Universitat Dr. C. Kim Wong, Biology, The Chinese Hamburg, Zoologisches Institut und University of Hong Kong, Shatin, NT, Museum, Martin-Luther-King-Platz 3, Hong Kong 20146 Hamburg 13, Germany b164762!hp720a. csc. cuhk. hk

Dr. Jeannette Yen, Marine Sciences Dr. Richard K. Zimmer-Faust, Research Center, State University of New University of South Carolina, York, Stony Brook, NY 11794-5000, USA Departmentof Biological Sciences, jyent9ccmaik sunysb.edu Columbia, SC 29208, USA d ickt9tbone. biol. scarolina. edu

51 Acuna, J.-L. 12 Hansson,L.J. 28 Schmitz, B. 40 Ambler, J.W. 12,18 Hartline, D.K. 28,29 Sebens,K.P. 29 Anderson, P.A.V. 39 Heid elberg, K.B. 29 Anger, K. Snell,T.W. 32,41 43 Herren, C. 29 Atema, J. Spencer, A.N. 41 13,22 Huang, L.M. 45 Bleckmann, H. Stabell, O.B 22 13 Huys, R. 15 Starkweather,P.L. 42 Bochdansky,A.B. 14 Jordan, S. 40 Stewart, S.E. 42 Bol lens, S.M. 14 Koehl, M.A.R. 30 Boxshall, G.A. Strickler,J.R. 15,21,43,45 15 Kracht, M. 12 Breithaupt, T. Suchman,C.L. 19 15,22 Lagro, M. 40 Brewer, M.C. Sullivan, B.K. 19 16 Land, M.F. 34 Broadwater, S.A. Titus, M. 40 12 Larsson, P. 30 Browman, H.l. Walter, I. 43 16 Latz, M.I. 3],38 Budel mann, B.-U. Weatherby,T.M. 44 17 Laverack, M.S. 31 Bundy, M.H. Widder, E.A. 24 17 Lenz, P.H. 28,29,44 Buskey, E.J. Wiese, K. 44 12,18 Loew, E.R. 35 Butler, N.M. Wong, C.K. 45 18 Lonsdale, D.J. 32 Caldwell, R.L. Yen, J. 15,21,23,45 20 Mackie, G.O. 32,33 Case, J.F. Zimmer-Faust, R.K. 46 19 Macmillan, D.L. 31 Chen, Q.C. 45 Madin, L.P. 33 Coats, J. 23 Marshall, N.J. 20,34 Colin, S. 45 Matsumoto,G.l. 34 Cordel1, J.R. 14 McAlary, F.A. 35 Costello, J.H. 19 McFarland, W.N 35 Cronin, T.W. 20 McNaught, D. 25 Deibel, D. 12,14 Mellon, D. 35 DeMeester, L. 20 Mogdans, J. 13 Doall, M.H. 21,45 Moore, P. 45 Dodson, S.l. 21 Morris, C.C. 12 Drewes, C. 23 Morse, A.N.C. 36,36 Falkenhaug,T. 22 Morse, D.E. 36 Farley, L.G. 22 Nilsson, D.-E. 37 Featherstone,D. 23 Norekian, T.P. 37 F iel ds, D.M. 23 Ohtsuka, S. 15 Fleck, A. 13 Okubo, A. 45 Forward, R.B. 24 Omori, M. 38 Frank, T.M. 24 Paffenhoeffer 17 Frey, M. 32 Peterson, J.O. 12,18 Frost, B.W. 14 Popper, A.N. 38 Fukami, H. 38 Przysiezniak,J. 41 Gait, C. 25 Purcel1, J.E. 29,39 Gokcen, J. 25 Raimond i, P.T. 36 Gool, E. van 26,39 Rico-Martinez, R 41 Greve, W. 26 Ringelberg,J. 26,39 Grigoriev, N. 41 Robertson,K. 40 H adti el d, M. 27 Sandow,S.L. 31 Hamner, W.M. 27 Satterlie, R.A. 40

52 No+ES NoTES NOTES Novas