I. Deep Sea Fishes Deep Sea Fishes II. Nocturnal-Diurnal Changeover (Twilight)
http:// www.youtube.co m/watch? v=dFhoIu4VKms
19 cm black swallower with 86 cm snake mackerel in its stomach
Definition of open ocean habitats Types of Deep Sea Fishes • Mesopelagic Benthal • Bethopelagic • Bathypelagic • Benthic Name Depth Largest habitat type on earth! Epipelagic 0-200 m (75% of ocean) Mesopelagic 200-1000 m Bathypelagic 1000-4000 m
Deep Sea Abyssal 4000+ (up to 8000 m!)
• Primary production via photosynthesis occurs only in epipelagic (euphotic) zone – where does the base of the food chain come from in the deep sea?
8000 m!
Types of Deep Sea Fishes Convergent Evolution: • Mesopelagic (~750 species) • Bathypelagic (~200 species) Organisms exposed to similar selective pressures are • Benthal (Bethopelagic & Benthic) (~1000 species) likely to evolve similar adaptations
Taxonomically diverse, but many common features: Selective Pressures in the deep sea: photophores (light emitting organs) large mouths • pressure dagger-like teeth • temperature lures • light • food thin bones • space enlarged, tubular, or reduced eyes Why??
1 Pressure • every 10 m of depth adds 1 atm of pressure (14.7 lb/in2) surface = 1 atm Pressure (cont.) 10 m = 2 atm • at great pressures, volume of water & protein molecules 200 m = 21 atm decreases 1000 m = 101 atm 8000 m = 801 atm (12,000 lb/in2) -- affects rates of chemical reactions
• presents challenges for using gas bladder solutions: solution: – close gas bladder duct (“secondary pysoclistous”) – proteins that are less sensitive to effects of pressure (found – longer rete mirable in deep meso- and bathypelagic species) – use lipids for buoyancy – reduce heavy tissues (bones & muscles) – eliminate gas bladder (benthal & bathypelagic) zone rete length (mm) epipelagic < 1 mm mesopelagic 1-7 mm bathypelagic 15-20 mm
Temperature Light – the deep ocean is dim or dark
• low & constant in deep areas (2-5º C in bathypelagic region) • up to 20º C difference for vertical migrators
Consequences: –species are usually found in specific temperatures regardless of latitude (i.e., different depths) –vertical migrators have more DNA per cell, possibly for multiple enzyme systems for different temps.
temperature fishes 10-20º C Myctophids; Stomiidae zone 5-10 Sternoptychids; pale Cyclothone epipelagic euphotic 2-4 Ceratioid anglers; dark Cyclothone mesopelagic twilight bathypelagic sunless
Adaptations for low-light or no-light Food
• Food is scarce, patchy, and unpredictable in the deep sea Mesopelagic Bathypelagic • must be able to… • large eyes • small eyes (used for 1. go long periods without food photophore detection • pure rod retinas (max ) 2. obtain any food available sensitivity to blue-green) • free neuromasts fangtooth (Anoplogastridae) • eye elongation • use of other senses (e.g., barrel eye) (e.g., olfaction) Adaptations: • bioluminescence • daggar-like teeth (5 superorders + Squaliformes) • huge mouths • huge stomachs Overall: • pectoral girdle free from -- more sensitive eyes (15-30 x more than humans) skull in some species -- can detect light deeper than human eyes • lures
2 Lures Going long periods without food: adaptations for energy conservation in deep sea fishes illicium esca • low metabolism • bone loss and reduction • loss of scales • reduction in musculature
Space female Male Cyclothone have highly • the deep ocean is vast & densities of fishes are extremely low developed olfactory abilities -- hard to find food & mates -- e.g., 1 female ceratioid anglerfish per 800,000 m3 (a football in a darkened stadium)
sexual dimorphism related to mate finding… Males: Females: • small • large • large olfactory organs • small olfactory organs • red muscle • white muscle male • highly developed eyes • poorly developed eyes • high lipid reserves • low lipid reserves
• also protandrous sex change in Cyclothone • simultaneous hermaphroditism in some groups
Mesopelagic (~750 species) (superorders, orders, & families) Elopomorpha – Notacanthiformes (Notacanthidae) – Anguiliformes (Nemichthyidae; Synaphobranchidae) Taxa of Deep Sea Fishes Protacanthopterygii – Argentiformes (Microstomatidae; Opisthoproctidae; Alepocephalidae; Platytroctidae) Stenopterygii – Stomiiformes (Gonostomatidae; Sternoptychidae; Stomiidae) Cyclosquamata – Aulopiformes (Giganturidae; Synodontidae; Paralepididae; Evermannellidae; Alepisauridae) Scopelomorpha – Myctophiformes (Myctophidae; Neoscopelidae) Lampriomorpha – Lampriformes (Stylephoridae) Acanthopterygii – Stephanoberyciformes (Mirapinnidae) – Perciformes (Chiasmodontidae; Gempylidae)
3 Bathypelagic (~200 species) Elopomorpha Benthal (Bethopelagic & Benthic) (~1000 species) –Anguiliformes (Nemichthyidae; Serrivomeridae; Elopomorpha Saccopharyngidae; Eurypharyngidae) – Notacanthiformes (Notacanthidae; Halosauridae) Protacanthopterygii – Anguiliformes (Synaphobranchidae) – Argentiformes (Alepocephalidae) Cyclosquamata Stenopterygii – Aulopiformes (Chloropthalmidae; Ipnopidae) – Stomiiformes (Gonostomatidae) Paracanthopterygii Paracanthopterygii – Gadiformes (Merluccidae; Moridae; Macrouridae) – Gadiformes (Melanonidae; Macrouridae) – Ophidiiformes (Ophididae; Bythitidae; Aphyonidae) – Ophidiiformes (Ophididae; Bythitidae) – Lophiiformes (Ogcocephalidae) – Lophiiformes (Ceratiidae) Acanthopterygii Acanthopterygii – Beryciformes (Caproidae) – Stephanoberyciformes (Melamphaidae; Stephanoberycidae; – Scorpaeniformes (Liparidae) Cetomimidae) – Perciformes (Zoarcidae; Bathydaconidae) – Beryciformes (Anoplogastridae) – Perciformes (Chiasmodontidae)
Elopomorpha Anguiliformes, Nemichthyidae (snipe eels) Mesopelagic Fishes
PROTACANTHOPTERYGII PROTACANTHOPTERYGII Argentifomres, Opisthoproctidae (barrel eye) Argentiformes, Microstomatidae
http://www.youtube.com/ watch?v=RM9o4VnfHJU
Bathylagus large eyes Tubular eyes for light sensitivity and depth perception
4 STENOPTERYGII STENOPTERYGII (all deep sea) • Sternoptychidae Stomiiformes (hatchetfishes) Stomiidae (barbeled dragonfishes) Light Production: • symbiotic bacteria • luciferase
Bioluminescence has evolved in 5 Superorders & >500 spp. CYCLOSQUAMATA (Protacanthopterygii, Stenopterygii, Scopelomorpha, Paracanthopterygii, (cyclo = cycloid scales) Acanthopterygii + Squaliformes) – Sex recognition • almost entirely deep sea fishes – Species recognition (like fireflies) • up to 2 m
loosejaws (Stomiidae) may have their own private communication channel: produce and detect red light
SCOPELOMORPHA Superorder Lampriomorpha “Strange Jaws” • all deep sea • ctenoid scales dragonfish larvae
Myctophidae (lanternfishes) • diverse group >200 spp. • deep scattering layer (gas bladder reflection) • taxonomy based on photophore patterns • tube eyes • 40 fold expansion of mouth volume during plankton feeding!
5 LAMPRIOMORPHA, Regalecidae 8 m long! little known
Bathypelagic Fishes
http://www.youtube.com/ watch?v=__r2df_5S9M
Elopomorpha, Saccopharyngiformes (gulper eel) STENOPTERYGII, Gonostomatidae (bristlemouths)
• huge mouth • no opercular bones, branchiostegal rays, scales, pelvic fins, ribs, gas bladder, etc. • most abundant and widely distributed vertebrates on earth! • “Perhaps the most anatomically modified of all vertebrate species” - Joe Nelson • representatives in both mesopelagic and bathypelagic
Paracanthopterygii, Gadiformes, Macrouridae (grenadiers/rattails) Paracanthopterygii, Lophiiformes Deep Sea Anglerfishes (Ceratioid Anglerfishes)
• diverse group: 150+ spp. • lures • what sex?
6 • males are small (males 2-4 cm max, females normally 10x longer than males, up to > 1 m long)
• neither sex matures until the male has attached
Benthopelagic and Benthic Fishes
Squaliformes (to 1000 m) Hexanchiformes (to 1600 m) (prickly dogfish, Oxynotus bruniensis) (frilled shark, Chlamydoselachus anguineus) http://www.youtube.com/ watch? v=qYH32gKMHuc
Lamniformes (to 1300 m) (goblin shark, Mitsukurina owstoni)
http://www.youtube.com/ watch?v=eh_HUIJkRzU
Cyclosquamata, Aulopiformes - tripodfishes (Ipnopidae) Paracanthopterygii Ophidiiformes Ophidiidae
Deepest fish known is a cusk eel, Abyssobrotula (8370 m)
7 Paracanthopterygii, Lophiiformes Acanthopterygii Sea toads (Chaunacidae) Scorpaeniformes http://www.youtube.com/watch? fathead sculpins (Pyschrolutidae) v=Cl_MbvSUvTk
Chaunacops coloratus
Acanthopterygii Acanthopterygii Scorpaeniformes http://www.youtube.com/watch? Perciformes v=0mKotQs93Dc snailfishes (Liparidae) Zoarcidae (eelpouts)
Diel Variation in Fish Activity Periods
• Diurnal (day-active): 50-66% of fishes II. Light, Vision, & Ecology
• Nocturnal (night active): 25-33%
• Crepuscular (dawn and dusk): 10%
8 Diel light patterns are strong and predictable Coral reefs have the strongest patterns of & cause strong temporal patterns in fish activity diurnal-nocturnal changes in fish assemblage
• family-level patterns – most families are diurnal
– key nocturnal families: • Apogonidae • Holocentridae • Muraenidae Light Intensity
Time
Diurnal families diurnal zooplanktivorous fishes • Brightly colored • huge stationary schools • Schooling or Territorial • visual feeders on small plankton • Herbivorous (all herbivores are diurnal) • predator detection (many eyes) Damselfishes Parrotfishes (Scaridae) (Pomacentridae) anthias (Serranidae)
Rabbitfishes (Siganidae) wrasses (Labridae) Surgeonfishes (Acanthuridae)
Nocturnal Fishes Zooplanktivores (cont.) • ecological replacement sets for most diurnal groups Zooplanktivores
Squirrelfishes (Holocentridae)
Why don’t nocturnal fishes form large schools? Bigeyes (Priacanthidae)
9 Zooplanktivores (cont.) Haemulidae (Grunts) • large daytime resting schools Cardinalfishes (Apogonidae) • forage in sand and seagrass at night
Nocturnal Predators Diurnal and Nocturnal Fishes-Summary
• more schooling in the day (both prey and predators) • diurnal species more colorful • no cleaner fishes or herbivores at night, but ecological replacement sets for other groups
mucous cocoon may protect parrotfishes from predators that use olfaction
Sequence of events on a coral reef at dusk: 1. migration of diurnal fishes (vertical or horizontal) 2. quiet period 3. shelter seeking (site fidelity) 4. emergence of nocturnal fishes
10 Family-level patterns: related to visual abilities cover seeking/emergence cover seeking/emergence
diurnal spp
The quiet period (~15-30 min after sunset)
nocturnal spp
Why is this a dangerous time to be in the water?
• Reaction distance of prey is shorter during twilight Diurnal Eyes (many small cones) • high light levels • resolution • Predators have intermediate eyes • motion detection • color vision visual advantage at twilight!
Nocturnal Eyes (rod dominated, few large cones) • light capture
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