Deep-Sea Communities OCN 201 Biology Lecture 13 Deep Sea • Physical Conditions •- Cold •- High Pressure •- Dark • Animals (and food) are sparse Deep Scattering Layer Vertical Migration by Plankton Sonar • se Food for the Deep • 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. Adaptations in the Deep Sea - Clear bodies or reflective sides and counterillumination (disphotic zone) - Red or Black bodies (aphotic zone) - Oversize mouths - Specialized eyes (or degenerated) - Bioluminescence Red or Black Bodies Red looks black in blue light Architeuthis - the giant squid Vampyroteuthis infernalis What does this thing eat? marine snow?! Big Mouths! Bioluminescence Some fish that use bioluminescence Light produced by a biochemical reaction USED FOR: • Counterillumination (camouflage) • Communication (finding mates) • Lures (enticing prey) • Searchlights (illuminate prey) • Decoy or surprise (escape from predator) Deep Sea Floor (about 3 km deep) ✦ Low Numbers (not much food) ✦ High Diversity (resource limited) ✦ Long Lives (low metabolic rates) ✦ Many deposit feeders and scavengers (about 4.8 km deep) ✦ Epifauna - urchins, brittle stars, crinoids, etc ✦ Infauna - crustaceans, worms, etc. Tripod Fish Brittle Stars Hydrothermal Vents & Cold Seeps • Specialized benthic habitats • Oases with very high abundance of organisms (Why?) • Primary Production by Chemosynthesis! Hydrothermal Vents Cold Seeps - hydrogen sulfide (H S) H S 2 2 - methane (CH ) 4 Photo- vs Chemosynthesis Light Energy 6CO2 + 6H2O C6H12O6 + 6O2 O2 + H2S Chemical Energy 6CO2 + 6H2O C6H12O6 + 6H2SO4 The Deep Sea - Summary • 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.