Biological adaptations of deep sea fishes Ashley Fooy

Biological adaptations of deep sea fishes Ashley 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 200 m lower 11, 000 m Pressure; 1000 x the atmospheric pressure Temperatures; -1 C to 4 C

Adaptations • High Pressures o Reduced skeleton and o • muscle mass 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 organs Intrinsic; chemical reactions under neural/hormonal control o Extrinsic; symbiotic relationship with bioluminescent bacteria under mechanical control o

Bioluminescence (Con't) • Usage Attract/ startle prey o Confuse predators § Mimic light traveling in a different direction o Attracting a mate o Counterillumination § Use photophores to match the light radiating from the environment o

• • • 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 o light to match an illuminated background) Cooperative swimming/hunting and sex signaling

Anglerfishes • Order Lophiiformes, Suborder Ceratioidae

Anglerfishesbioluminescence • • Structure of escal photophore o fluorescent bacteria Purpose of escal photophore

Anglerfishes - feeding and locomotion • lie-in-wait predator interesting adaptation when feeding on the bottom o diet o • common locomotive patterns passive drifting o movement when threatened o

Anglerfishes reproduction • two reproductive strategies fusion o temporary attachment o • Male anglerfish larva sexual dimorphism

Deep-sea hatchetfish • • Argyropelecus affinis or Argyropelecus hemigymnus Adaptations o Upward facing snout, mouth o Upward facing, large, tubular eyes o 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 pigmentation o Increased acuity o Detect own group o Avoid enemies o Chemical properties differ from other species with coloration Sexual dimorphism in olfactory organs o Males larger than females o Pheromone responses

Umbrella Mouth Gulper eel Adaptations: Pelican eel Enlarged mouth & head o "Largest gape size of any • Saccopharyngiformes Eurypharynx pelecanoides • • • vertebrate in relation to body size" (Nielsen, 1989 p. 194). Extended lateral line Luminous filaments on caudal fin used for hunting Leptocephalic Larve o Similar to relatives they breed once and die (semelparity)

Umbrella mouth Gulper eel Ambush hunting • • • Lure hunting Uses lateral line to detect prey Lunges at prey using water to open mouth similar to a parachute o Only has to expend energy closing jaw Typically used when hunting small prey • • • 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

Conservation • • Largest ecosystem with least know about it o Millions of square miles of • Possibly the largest reservoir of biomass on the planet o Number of species living • unexplored ocean floor 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

Conservation Environmental 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