44 Synonyn>:Orcbestia agilis Smith, 1873 of decapods,Instead of the female incubating the Recognition Characters: Body reaching 12 mm in eggson her pleopods,the fertilizedeggs are released length; second antenna approximately 3 times longer directly into the water.A free-swimmingnauplius than first with peduncle segmentsthickened in adult larva hatchesfrom the egg and, after severalmolts, males; second gnathopod of male with dactyl metamorphosesinto a shrimp-likelarval stage called reaching hack less than one hal f length o I' palm a zoea. 'I'he z<>ca molts several more times before propodus!; first uropod with outer ramus lacking becoming a postlarva.The Pcnaeideaare the only lateral spines. group of dccap<>dcrustaceans known to have a I'rec- Distribution: Widely distributed throughcrustacean groups such as world, nearly cosmopolitan, cephal<>caridians,copepods, and barnacles, Habitat: I'.uryhafinc in upper intertidal and supratidal zones; under dead vegetation and other debris; I' twm- speciesof the genus Penaeusforage in tidal marshes ponent of open shore and beach comrnumties and during high fides and occasionally <>ccurtemporarily serves as an important I'ood fnds. birds. Members of thc genusPenaeus breed hl of fshvcr thc c<>ntincntal she]f'. IIere the pelagic nauplius and zoeal stages occur. The post-larvae Superorder Eucarida mi brackisli water bays where they develop Order Decapoda into juveniles. Nurtured by the rich food supplies available in the esf.uarineand adjacent.tidal-rnarshes, The Decap<>ciaare considered the mostadvanced the yw rapidly. Af'ter r group of' crustaceans.Appr<>ximately 9,000 species four months in these estuarine "nurserygrounds," are presently known. The order containsthe larger t.hey become subadults, large enough t<>be aught and better known crustaceans, such as 1<>bsters, commercially, The subadut ts migrate to offshore crayfishes,hermit crabs, shrimps, and crabs. The waters, where they mature into adults that form the decapodbody plan is generally shrimp-like Cari- breedingstock for the next year's "crop." The Gulf doid! or crab-like cancroid!. The order is character- speciesof Penaeusrarely live over one-and-a-halfto ized by the following: ! modification of the first two years. three pairs of thoracic appendagesinto mouth parts maxillipeds!; ! five pairsof legs hencethe term Penaeus aztecus Ives, 1891 "decapods"!; ! a shellor carapaceformed from the F>gure 50 b, d fusion of the head and thoracic segmcatscovering the head, thorax, and associatedcoxial gills; and ! us- Common Name: Brown Shrimp ually planktonic larval stages. Recognition Characters: T pair larval stages. of well-developed grooves cxtcl>ding on either side Over 20 difterent. species <>I recap<>dsoccur <>frostral keel to near posterior margin. in <>ralasts <>f UniteNorth Carolina to Texas; Central Anicrica; goriespresented in illo<>rc969j. northern S <>ut h Am erica. Habitat: Plankt<>nie larvae and ailfs in stiallff- Suborder Dendrobranchiata shore waters; post-larvaeand juveniles in estuaries. Infraorder Penaeidea Remarks: From April thr<>ugh the summer months the postlarvae and juveniles of brown shrimp often This gr<>upund the tida! marshes, Fdib! c-size the first thrcc pairsof legsbeing chclate; and ! the juveniles are present in late May and Jun<.. 'I'hcy grt<>vcrlapping those of the first, The life cycle shore waters in late June and early July. of the Dendrobranchiatadiffers from all other groups References: Farfante 969!; Williams 965!. 45

~ b-e! 2.0 t.rn ~ f! 2.Q mrn

Fi re 50. a Pevaeus setiferus;,; b c d ors salaspects of thecarapaces of Penaeus aztecus and P. seriferus, rcs i;, . d P . J' resectively dorsal aspects of last sixth!abdominal seg- mentsUropods and telsons f Palaemonetespugio,dorsal aspect of the telson and uropo a a ter Williams,1965; b, c after Farfante,1969!. 46 Penaeussetiferus L., 1767! andrails, Marsh grass shrimps are opportunistic feed- Figure 50 a, c, e ers and eat a varietyof animaland plant matter, in- cluding detritus, meiofauna, algae, ann Guff estuaries and often feenthslater than brown shrimp and thus the the transparentbodies of infectedmarsh grass shrimp. postlarvae of white shrimp arrive in the estuaries Three other speciesof grassshrimps, P. vulgaris later. Juvenile white shrimp usually become numer- Say, 1818!, P. paludosus Gibbes, 1850!, and P. ous in July and August and remain in the bays and kadurkensis Rathbun, 1902!, may also occur in the estuaries until f'all and the advent. of cold weather; vicinity of tidal marshes.Palaernonetes vulgaris Fig. then as subadults, most leave the estuaries f<>r off- 51 c, d! is distinguished from P. pugio by the follow- shore waters. ing: ! P. vulgarishas a rostrumwith teeth nearly References:Farfante f969!; Williams965!. reaching the tip; ! the palm of the second leg of the female P. vulgaris is distinctly longer than the carpus;and ! P. vulgarishas small teeth on the Suborder Pleocyemata chela of its second legs two on the movable finger Infraorder Caridea and one on the fixed finger!. Although P, pugio and P. vulgaris occasionally occur together around oyster Carideanshrimps differ from penaeidsin two reefs adjacent to the salt marshes,P. vulgaris usually ways: I! carideanshave non-chelate third legs; and is more commonly associatedwith fouling organisms ! the pleura of the second abdominal segment of barnacles, hydroids! on dock pilings and shell bot- carideans overlaps the first and third segments, Fe- toms. Palaeornonetesvulgaris is also more sensitiveto rnale carideans carry their fertilized eggs on their low salinities and usually does not occur in waters be- pie<>p<>ds,A plankt<>nic nauplius stage is absent, and low 10/<><>. zoeahatch directly from the eggs. Palaernonetespaludosus and P. kadiakensis re- place P. pugio in the freshwater tidal marshesadja- I'amily Palaemonidae Palaernonid Shrimps! cent to the mouths of rivers. All three species,how- Palaemonetespugio Holthuis, 1949 ever, may occasionally occur together in oligohaline conditions. Distinguishing characters for separating Figure 51 a these three speciesare presented in the key and illus- trated in Fig. 51 a, e, f. Common Name: Marsh GrassShrimp Another palaemonid shrimp, rWacrohrachium Recognition characters: .Tip of rostrum blade-like, ohione Smith, 1874!, may also be found with lacking spines; second legs larger than first with P. puli o in oligohaline tidal marshes,especially those chela lacking teeth; palm propodus! shorter than adjacent t<>the m<>uih<>I the Mississippi River, The carpus in female; branchiostegal spine present; juveniles of A4, ohione are similar to adult P. pugio, hepatic spine absent. but the presence of a hepatic spine and the lack Distribution: Atlantic and Gulf coasts from Massa- of a branchiostegalspine on M ohione Figure 51 g! chusetts to Texas, readily separates the two forms. Habitat: Euryhaline less than l%%uooto over 30%%uo<>!References: Holthuis 952!; Overstreet f 1978!; in bays and tidal creeks; comm<>n in shallow water Welsh 975!; Williams 965!. in or around tidal marshes, submerged vegetation, and oyster reefs. Infraorder Anornura Remarks: Palaemonetespugio is a year-r<>undresident in Gulf coast estuaries, It is eaten by many animals The anomurans comprise a morphol<>gically including estuarine fishes, blue crabs, herons, ducks diverse group of crustaceanswhich include the hermit crabs, mud shrimps, mole crabs, and porcellanid 1935, and Caltianassatrilobata Biffar, 1971, which crabs.One speciesoI' hermit crab commonlyoccurs live in deepburrows, occur in thesubstrata along the in salt rnarshesbordering open bays and largebay- edgesof tidal marshesof the northernGulf. These ous.Also, three species of mudshrimps, Upogebia af- threemud shrimpsare not discussedbelow, but are finis Say, 1818!,Callianassa jamaicense Schmitt, included within the taxonomic key,

I.O mm

Figure51, a Palaemonetespugio;b, c P,pugio and P. vulgaris, respectively, chelaeof second legs; d-g lateralaspects ofthe rostra and anterior parts ofthe carapace; d P. vuIgaris; e P. paludosus; f P.krtdiakensis; and g Nacrobrachiumohione. e, f afterHolthuis, 1952!. Family Diogenidae Diogenid Hermit Crabs! Infraorder Brachyura Crabs! Clibanariusvittatus Bose, 1801 or 1802! Figure 52 The Brachyura, or true crabs, have reduced ab- domens that lack urop<>dsand are tightly flexed un- Common Name: Striped Hermit Crab derneaththeir cephalothoraces.These features distin- Recognition Characters: Abdomen asymmetrical, guish brachyurans from thc superficially similar modified for <>ccupyinggastropod shells; chclipcds porcellanid "crabs" of the inlraurmenswith uropods. longitudinal stripes. I'<>ur fan>ilies of crabs, ><..presentedby at least 15 Distribution: Atlantic and Gulf coasts of North different species,<>cc«r on or along the «lg1 America; Central America, and South America from northern Gulf tidal marshes. Virginia to Brazil Rio de Janeiro!. Family Portunidae Swimming Crabs! Habitat: Shallow subtidal to intertidal zone; meso- haline to polyhaline 0%o to over 35%o!; common Callinectessapidus Rathbun 1896 un r<>ckjetties, protected beaches, and in salt marshcs Figures 53,54 near thc open Gulf'. Remarks:The adults and especiallythc juvcnilcs ol' Common Name: Common Blue Crab this c<>mmonhermit eral> are often present in tidal Recognition Characters: Last pair of legs with ter- marshesnear the Gulf. In salt marshes,juveniles minal segment oval and flattened, modified for swim- usually occupy stoften utilize sharp, strongly developed; four notches on frontal the shellsuf OysterDrills, Crowr>Conchs, and Moon margin between eyes; chelipeds of females and sub- Snails. 'I'hc Stripe<1I Icrmit Crab is an omnivorous adult maleswith red areaon palm. sca.vengcr. Distribution: I'.ast and Gulf coastsof N<>rthAmerica, References:Williams I!! 65!. Central America, and South America fr<>rni>>lassachu-

Figure52. Clibanariusvittatus removed from a gastropodshell, large adult life size. 49 setts to southern Brazil; Bermuda;EVestIndies, important commercialfishery. After mating and a Habitat: Euryhaline less than 1%o to more than period of feedingin the estuary,the adult females 3 5%o!; throughout all estuarineintertidal and sub- form an egg masswhich is attachedto the pleopods tidal habitats. under the abdomen. Ovigerous females are often Remarks: The blue crab is the most common large called "sponge" crabs becausetheir large egg masses estuarine crab in the northern Gulf and supports an resemble sponges.A single "sponge" crab may carry

'j»!

» «

Figure 53. Cal1inectessapidus, dorsal aspects. a adult male; b adult female.

»

"j»'!.' e '»'!

!!»l!j '!l!» s ! ».e»,l» «f l!» «k~!.,:»';' ~!ski:A~.' P~~«~» Figure 54. Cal1inectessapidus, ventral aspects. a adult,non-ovigerous female; b adult male; c- adult ovigerousfemale; d immature fernale; e immature male.