OCN 201 Biology Lecture 13

Deep-Sea Communities

• Physical Conditions•- Cold•- High Pressure•- Dark

• Animals (and food) are sparse

Deep Sea

• se

Deep Scattering Layer

Sonar

Vertical Migration by Plankton

• Detritus from the surface ocean food web falls down to the deep sea

• This falling detrital material is marine snow, fecal pellets and occasional dead animals

• Marine Snow consists of bits of aggregates of algae, discarded larvacean houses, microorganisms, etc.

Food for the Deep

- Clear bodies or reflective sides and counterillumination (disphotic zone)

- Red or Black bodies (aphotic zone)

- Oversize mouths

- Specialized eyes (or degenerated)

- Bioluminescence

Adaptations in the Deep Sea

Red or Black Bodies

Red looks black in blue light

Vampyroteuthis infernalis

Architeuthis - the giant squid

What does thisthing eat?

marine snow?!

Big Mouths!

• Counterillumination (camouflage)

• Communication (finding mates)

• Lures (enticing prey)

• Searchlights (illuminate prey)

• Decoy or surprise (escape from predator)

Bioluminescence Light produced by a biochemical reaction

USED FOR:

Some fish that use bioluminescence

✦ Low Numbers (not much food)

✦ High Diversity (resource limited)

✦ Long Lives (low metabolic rates)

✦ Many deposit feeders and scavengers

✦ Epifauna - urchins, brittle stars, crinoids, etc

✦ Infauna - crustaceans, worms, etc.

Deep Sea Floor(about 3 km deep)

(about 4.8 km deep)

Tripod FishBrittle Stars

Hydrothermal Vents & Cold Seeps

H2S

• Specialized benthic habitats

• Oases with very high abundance of organisms (Why?)

• Primary Production by Chemosynthesis!

Cold SeepsHydrothermal Vents- hydrogen sulfide (H

2S)

- methane (CH4)

Photo- vs Chemosynthesis

6CO2 6H2O+ C6H12O6 6O2+

LightEnergy

6CO2 6H2O+ C6H12O6 6H2SO4+

+O2 H2S Chemical Energy

• Physical Conditions•- Cold•- High Pressure•- Dark

• Animals (and food) are sparse

• Many special adaptations•- Clear, or at > 700 m: many are red or black•- Oversize mouths•- Bioluminescence•- Reduced silhouette•- Specialized eyes (or degenerated)

• Hydrothermal Vents and seeps• A second source of Primary Production in the sea

• Only bacteria can do it

• Animals with autotrophic endosymbionts result in rich oases in a food desert — just like coral reefs in tropical seas! — but the symbionts at vents are chemoautotrohs instead of photoautotrophs

The Deep Sea - Summary