Biological adaptations of deep sea fishesAshley Fooy, Rachel Krumbein, Gerald

Marsh, Sandhya Rajagopal

Introduction• 60% of the Earth's surface

• Boundaries; part of the ocean that spans beyond the continental shelf o Upper bound of 200m

lower 11,000m

• Pressure; 1000x the atmospheric pressure

• Temperatures; -1C to 4C

Adaptations • High Pressures

o Reduced skeleton and muscle mass

o Piezolytes; prevent distortion of molecules

• Colder temperatures o Flexible proteins and

unsaturated membranes

Adaptations (con't)• Food availability - limited

o Large mouth/jaw hinges, teeth that hook inward, and expandable stomachs

• Reproduction o Sexual parasitism

Bioluminescence • 80% of deep sea

fishes

• Photophores; light emitting organso Intrinsic; chemical

reactions under neural/hormonal control

o Extrinsic; symbiotic relationship with bioluminescent bacteria under mechanical control

Bioluminescence (Con't)• Usage

o Attract/ startle preyo Confuse predators

Mimic light traveling in a different direction

o Attracting a mateo Counterillumination

Use photophores to match the light radiating from the environment

Velvet Belly Lantern Shark• Important ecological

role; one of the most abundant predators

• Captured/discarded by several off-shore fisheries

• Nine luminous zones (hormonal control)o Counterillumination (produce

light to match an illuminated background)

o Cooperative swimming/hunting and sex signaling

Anglerfishes

• Order - Lophiiformes, Suborder - Ceratioidae

• Structure of escal photophoreo fluorescent bacteria

• Purpose of escal photophore

Anglerfishes-bioluminescence

Anglerfishes - feeding and locomotion

• lie-in-wait predatoro interesting adaptation

when feeding on the bottom

o diet

• common locomotive patternso passive driftingo movement when

threatened

Anglerfishes - reproduction

• two reproductive strategieso fusiono temporary

attachment

• sexual dimorphism

Male anglerfish larva

Deep-sea hatchetfish• Argyropelecus affinis or

Argyropelecus hemigymnus

• Adaptationso Upward facing snout,

moutho Upward facing, large,

tubular eyeso Narrow silhouettes,

silver sides

Deep-sea hatchetfish• Bioluminescence

o Camouflage, counterillumination

o Can rapidly alter luminescence according to background

o Possible nitric oxide modulation of luminescence

• Zooplanktivorous

• Lens pigmentationo Increased acuityo Detect own groupo Avoid enemieso Chemical properties

differ from other species with coloration

• Sexual dimorphism in olfactory organso Males larger than

femaleso Pheromone responses

Umbrella Mouth Gulper eel

SaccopharyngiformesEurypharynx pelecanoides

Adaptations: Pelican eel

• Enlarged mouth & heado "Largest gape size of any

vertebrate in relation to body size" (Nielsen, 1989 p.194).

• Extended lateral line

• Luminous filaments on caudal fin used for hunting

• Leptocephalic Larveo Similar to relatives they

breed once and die (semelparity)

Umbrella mouth Gulper eelAmbush hunting• Uses lateral line to detect prey

• Lunges at prey using water to open mouth similar to a parachuteo Only has to expend energy

closing jaw

• Typically used when hunting small prey

Lure hunting

• Ambush hunting of larger prey items

• Bioluminescent filaments on caudal fin are used to lure prey closer

• Before they swallow prey they digest it in its gape with an acidic substrate.

Conservation• Largest ecosystem with

least know about ito Millions of square miles of

unexplored ocean floor

• Possibly the largest reservoir of biomass on the planeto Number of species living

there may outnumber terrestrial animals

• Millions of years of evolution in a harsh environment requires very specialized adaptations

• Practical uses of fish adaptations for developing medicine

ConservationEnvironmental changes• "Undetected mass extinctions"

• So few interactions with them we have no idea if populations are declining

Human impacts • Deep ocean oil spills

o Event horizon spill

• Overfishing of top predators & fishing down the food web

Conservation is important because the benefits these fish can provide is highly unknown

Conclusion and future directions• more research is

needed for all species

• new technology• biological

adaptations are key to success in the deep sea