Biological adaptations of deep sea fishes

1. Biological adaptations of deep sea fishes Ashley Fooy, Rachel Krumbein, Gerald Marsh, Sandhya Rajagopal

2. Introduction • 60% of the Earth's surface • Boundaries; part of the ocean that spans beyond the continental shelf • Upper bound of 200m lower 11,000m • Pressure; 1000x the atmospheric pressure • Temperatures; -1C to 4C

3. Adaptations • High Pressures • Reduced skeleton and muscle mass • Piezolytes; prevent distortion of molecules • Colder temperatures • Flexible proteins and unsaturated membranes

4. Adaptations (con't) • Food availability - limited • Large mouth/jaw hinges, teeth that hook inward, and expandable stomachs • Reproduction • Sexual parasitism

5. Bioluminescence • 80% of deep sea fishes • Photophores; light emitting organs • Intrinsic; chemical reactions under neural/hormonal control • Extrinsic; symbiotic relationship with bioluminescent bacteria under mechanical control

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

7. 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) • Counterillumination (produce light to match an illuminated background) • Cooperative swimming/hunting and sex signaling

8. Anglerfishes • Order - Lophiiformes, Suborder - Ceratioidae

9. Anglerfishes-bioluminescence • Structure of escal photophore • fluorescent bacteria • Purpose of escal photophore

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

11. Anglerfishes - reproduction • two reproductive strategies • fusion • temporary attachment • sexual dimorphism Male anglerfish larva

12. Deep-sea hatchetfish • Argyropelecus affinis or Argyropelecus hemigymnus • Adaptations • Upward facing snout, mouth • Upward facing, large, tubular eyes • Narrow silhouettes, silver sides

13. Deep-sea hatchetfish • Bioluminescence • Camouflage, counterillumination • Can rapidly alter luminescence according to background • Possible nitric oxide modulation of luminescence • Zooplanktivorous • Lens pigmentation • Increased acuity • Detect own group • Avoid enemies • Chemical properties differ from other species with coloration • Sexual dimorphism in olfactory organs • Males larger than females • Pheromone responses

14. Umbrella Mouth Gulper eel • Saccopharyngiformes • Eurypharynx pelecanoides Adaptations: Pelican eel • Enlarged mouth & head • "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 Larve • Similar to relatives they breed once and die (semelparity)

15. Umbrella mouth Gulper eel Ambush hunting • Uses lateral line to detect prey • Lunges at prey using water to open mouth similar to a parachute • 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.

16. Conservation • Largest ecosystem with least know about it • Millions of square miles of unexplored ocean floor • Possibly the largest reservoir of biomass on the planet • 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

17. 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 • 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

18. Conclusion and future directions • more research is needed for all species • new technology • biological adaptations are key to success in the deep sea