Deep Sea Fishes

Deep Sea Fishes I.
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 Types of Deep Sea Fishes Definition of open ocean habitats Deep Sea Name Depth Epipelagic 0-200 m Mesopelagic 200-1000 m Largest habitat type on earth! (75% of ocean) Bathypelagic 1000-4000 m Abyssal 4000+ (up to 8000 m!) •
Mesopelagic •
Bathypelagic Benthal •
Bethopelagic •
Benthic •
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 •
Mesopelagic (~750 species) •
Bathypelagic (~200 species) •
Benthal (Bethopelagic & Benthic) (~1000 species) Taxonomically diverse, but many common features:

photophores (light emitting organs)

large mouths

dagger-like teeth

lures

thin bones

enlarged, tubular, or reduced eyes Convergent Evolution: Organisms exposed to similar selective pressures are likely to evolve similar adaptations Selective Pressures in the deep sea: •
pressure •
temperature •
light •
food •
space Why?? 1 Pressure •
every 10 m of depth adds 1 atm of pressure (14.7 lb/in2) surface = 1 atm 10 m = 2 atm 200 m = 21 atm 1000 m = 101 atm 8000 m = 801 atm (12,000 lb/in2) Pressure (cont.) •
at great pressures, volume of water & protein molecules decreases -- affects rates of chemical reactions •
presents challenges for using gas bladder

solutions: solution: –
close gas bladder duct (“secondary pysoclistous”) –
longer rete mirable –
use lipids for buoyancy –
reduce heavy tissues (bones & muscles) –
eliminate gas bladder (benthal & bathypelagic) zone epipelagic mesopelagic bathypelagic –
proteins that are less sensitive to effects of pressure (found in deep meso- and bathypelagic species) rete length (mm) < 1 mm 1-7 mm 15-20 mm Light – the deep ocean is dim or dark Temperature •
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 10-20º C 5-10 2-4 fishes Myctophids; Stomiidae Sternoptychids; pale Cyclothone Ceratioid anglers; dark Cyclothone Adaptations for low-light or no-light zone epipelagic mesopelagic bathypelagic euphotic twilight sunless Food •
Food is scarce, patchy, and unpredictable in the deep sea Mesopelagic •
large eyes •
pure rod retinas (max sensitivity to blue-green) •
eye elongation (e.g., barrel eye) Bathypelagic •
small eyes (used for photophore detection) •
free neuromasts •
use of other senses (e.g., olfaction) •
bioluminescence (5 superorders + Squaliformes) Overall: -- more sensitive eyes (15-30 x more than humans) -- can detect light deeper than human eyes •
must be able to… 1.
go long periods without food 2.
obtain any food available fangtooth (Anoplogastridae) Adaptations: •
daggar-like teeth •
huge mouths •
huge stomachs •
pectoral girdle free from skull in some species •
lures 2 Lures Going long periods without food: adaptations for energy conservation in deep sea fishes esca illicium •
•
•
•
Space •
the deep ocean is vast & densities of fishes are extremely low -- hard to find food & mates -- e.g., 1 female ceratioid anglerfish per 800,000 m3 (a football in a darkened stadium) low metabolism bone loss and reduction loss of scales reduction in musculature Male Cyclothone have highly developed olfactory abilities sexual dimorphism related to mate finding… Females: Males: •
small •
large •
large olfactory organs •
small olfactory organs •
red muscle •
white muscle •
highly developed eyes •
poorly developed eyes •
high lipid reserves •
low lipid reserves female male •
also protandrous sex change in Cyclothone •
simultaneous hermaphroditism in some groups Mesopelagic (~750 species) Taxa of Deep Sea Fishes (superorders, orders, & families)

Elopomorpha –
Notacanthiformes (Notacanthidae) –
Anguiliformes (Nemichthyidae; Synaphobranchidae)

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 –
Anguiliformes (Nemichthyidae; Serrivomeridae; Saccopharyngidae; Eurypharyngidae)

Protacanthopterygii –
Argentiformes (Alepocephalidae)

Stenopterygii –
Stomiiformes (Gonostomatidae)

Paracanthopterygii –
Gadiformes (Melanonidae; Macrouridae) –
Ophidiiformes (Ophididae; Bythitidae) –
Lophiiformes (Ceratiidae)

Acanthopterygii –
Stephanoberyciformes (Melamphaidae; Stephanoberycidae; Cetomimidae) –
Beryciformes (Anoplogastridae) –
Perciformes (Chiasmodontidae) Mesopelagic Fishes PROTACANTHOPTERYGII Argentifomres, Opisthoproctidae (barrel eye) Benthal (Bethopelagic & Benthic) (~1000 species)

Elopomorpha –
Notacanthiformes (Notacanthidae; Halosauridae) –
Anguiliformes (Synaphobranchidae)

Cyclosquamata –
Aulopiformes (Chloropthalmidae; Ipnopidae)

Paracanthopterygii –
Gadiformes (Merluccidae; Moridae; Macrouridae) –
Ophidiiformes (Ophididae; Bythitidae; Aphyonidae) –
Lophiiformes (Ogcocephalidae)

Acanthopterygii –
Beryciformes (Caproidae) –
Scorpaeniformes (Liparidae) –
Perciformes (Zoarcidae; Bathydaconidae) Elopomorpha Anguiliformes, Nemichthyidae (snipe eels) PROTACANTHOPTERYGII Argentiformes, Microstomatidae http://www.youtube.com/ watch?v=RM9o4VnfHJU Bathylagus Tubular eyes for light sensitivity and depth perception large eyes 4 STENOPTERYGII (all deep sea) Stomiiformes Stomiidae (barbeled dragonfishes) Bioluminescence has evolved in 5 Superorders & >500 spp. (Protacanthopterygii, Stenopterygii, Scopelomorpha, Paracanthopterygii, Acanthopterygii + Squaliformes) –
Sex recognition –
Species recognition (like fireflies) STENOPTERYGII •
Sternoptychidae (hatchetfishes) Light Production: •
symbiotic bacteria •
luciferase CYCLOSQUAMATA (cyclo = cycloid scales) •
almost entirely deep sea fishes •
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. •
“Perhaps the most anatomically modified of all vertebrate species” - Joe Nelson Paracanthopterygii, Gadiformes, Macrouridae (grenadiers/rattails) •
most abundant and widely distributed vertebrates on earth! •
representatives in both mesopelagic and bathypelagic 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) (prickly dogfish, Oxynotus bruniensis) Hexanchiformes (to 1600 m) (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 Sea toads (Chaunacidae) http://www.youtube.com/watch? v=Cl_MbvSUvTk Acanthopterygii Scorpaeniformes fathead sculpins (Pyschrolutidae) Chaunacops coloratus Acanthopterygii Scorpaeniformes snailfishes (Liparidae) http://www.youtube.com/watch? v=0mKotQs93Dc Acanthopterygii Perciformes Zoarcidae (eelpouts) Diel Variation in Fish Activity Periods II. Light, Vision, & Ecology •
Diurnal (day-active): 50-66% of fishes •
Nocturnal (night active): 25-33% •
Crepuscular (dawn and dusk): 10% 8 Diel light patterns are strong and predictable & cause strong temporal patterns in fish activity Coral reefs have the strongest patterns of diurnal-nocturnal changes in fish assemblage •
family-level patterns Light Intensity –
most families are diurnal –
key nocturnal families: •
Apogonidae •
Holocentridae •
Muraenidae Time Diurnal families diurnal zooplanktivorous fishes •
Brightly colored •
huge stationary schools •
Schooling or Territorial •
visual feeders on small plankton •
Herbivorous (all herbivores are diurnal) Damselfishes Parrotfishes (Scaridae) •
predator detection (many eyes) (Pomacentridae) anthias (Serranidae) Rabbitfishes (Siganidae) wrasses (Labridae) Surgeonfishes (Acanthuridae) Zooplanktivores (cont.) Nocturnal Fishes •
ecological replacement sets for most diurnal groups Zooplanktivores Squirrelfishes (Holocentridae) Bigeyes (Priacanthidae) Why don’t nocturnal fishes form large schools? 9 Haemulidae (Grunts) Zooplanktivores (cont.) Cardinalfishes (Apogonidae) •
large daytime resting schools •
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? Diurnal Eyes (many small cones) •
high light levels •
resolution •
motion detection •
color vision •
Reaction distance of prey is shorter during twilight •
Predators have intermediate eyes
visual advantage at twilight! Nocturnal Eyes (rod dominated, few large cones) •
light capture 11