Deep Sea Friday April 24 2015 12 01 PM 4 24 15 The Deep Sea 1 Extent of the Deep Sea 2 Conditions in the Deep Sea A Cold B High Pressure C Dark D Low Biomass 3 Hydrothermal Vents 1 Extent of the Deep Sea 75 of the ocean reaches depths 3000 m Much is broad flat sediment covered To 6000 m Most extreme pressure environments on earth One of the most inaccessible environments on earth Expensive Difficult to bring intact animals to surface Difficult for humans to enter environment Studies of deep sea habitats fragmentary deep sea is about 4000 m 1 Conditions in the Deep Sea Conditions are extreme but relatively constant A High Pressure 300 600 atm B Cold C Dark 2 C below 3000 m Specialized eyes Many bioluminescent animals D Low Biomass little food How do deep sea organisms deal with these extreme conditions A and B High Pressure Cold Enzymes of closely related deep and shallow water spp differ Abyssal plains separated by oceanic mountain ranges ridges and deep trenches Enzymes operate optimally within a range of temperatures Enzymes of deep sea organisms most efficient at catalyzing reactions at low temps Phospholipids PL in cell membranes of deep and shallow water animals differ Phospholipids must remain fluid for proper cell function High pressure cold temp reduces fluidity Cell membranes PL of deep sea animals are unsaturated contain double bonds Kinky PL with double bonds cannot be packed together as tightly as PL with no double bonds saturated Kinky PL with double bonds respond differently to temp than PL with no double bonds saturated Fluidity of cell membranes maintained under high low temp Deep Sea and polar fishes very unsaturated and Antarctic spp because it is cold Unsaturation contains double bonds A Dark Bioluminescence already looked at Eyes of deep sea animals are specialized Size Rods Often larger Permit more light to retina More rods as many as 6 layers vs 1 or 2 in shallow animals Closely packed Sensitivity to light More sensitive eyes Detect light levels 100x lower than humans Pigments Tapetum lucidum Retinas of deep water animals contains different types of pigments than retinas of shallow water animals Deep sea eyes most sensitive to light of 480 nm wavelength blue light Shallow organisms most sensitive to light of 520 nm wavelength Guanine layer behind retina Reflects light back through photoreceptors a 2nd time Shutter system opens and closes exposing guanine Activated at night in shallow animals Constantly functioning in deep water fish No sunlight no photosynthesis What is the source of energy in deep sea Energy comes from above Small of surface production reaches depths Dead phytoplankton zooplankton crustaceans from above Some only available after bacterial breakdown Pigments Tapetum lucidum A Low Biomass Majority of benthic feeders are deposit feeders Engulf sediment and extract bacteria and dead organic matter Low Biomass but fairly diverse communities Reproduction Few planktonic larvae little chance of reaching photic zone Tendency towards few large eggs Shift in common spp Polychaete other worms echinoderms sea cucumbers crustaceans isopods amphipods Decreased abundance of seastars bivalves and other mollusks Less energy available for consumption means Less energy for metabolism Consequences lower metabolic rate in deep sea animals Less energy for growth Consequences slower growth and smaller size in deep sea Small vulnerable to predation How do you get big with little energy for growth Reduce energy unit volume Increase low energy matter water Decrease high energy matter muscle Many deep sea animals are soft and flabby Less energy for locomotion Consequences less energy for locomotion in deep sea Can reduce energy for locomotion with increased buoyancy Density g cm3 Animals that are more dense than SW have to swim expend energy to maintain position in water column avoid sinking Decreased density increased buoyancy allows animals to maintain position in water column using less energy When density of an animal SW the animal is neutrally buoyant Many deep sea animals are neutrally buoyant selection pressure Approaches to reducing density increasing buoyancy 1 Reduce dense matter Skeleton muscle skin 2 Increase light matter Gas lipid water Lipids ovary water light matter Density of sea water 1 027 g cm3 Organs skin muscle skeleton dense matter The density of an animal 1 Reduce dense matter Reduce heavy ions Mg SO4 4 27 Cuttlefish jellyfish tunicates sea slugs deep sea and pelagic squid exchange these for lighter ions Reduce heavy skeletal matter Ca P CaCO3 Pelagic gastropod mollusks Antarctic and deep sea fishes Deep sea sharks in skin and skeleton Increased light matter in deep sea animals 2 Gas floats Swim bladders subject to tremendous pressure Gas enclosed in more rigid structures Chambered nautilus Cuttlebone of cuttlefish Synthesis of low density lipids Found in many locations in animal bodies Liver head muscles bones skin swim bladder Oil Water Same density as environment can increase size without expenditure of energy by increasing water content of body Larger size fewer predators 1 Hydrothermal Vents Where tectonic plates move apart and crust is formed Seawater seeps downwards through crevices and is heated by the mantle magma Superheated water 350 C forces up through the crust forming hydrothermal vents The hot water is rich in silicates hydrogen sulfide H2S iron magnesium these crystalize as the water mixes with ambient water Communities characterized by chemoautotrophs tubeworms bivalve mollusks crustaceans very large animals and symbiotic animals Polar Seas 1 Polar Environments 2 Artic vs Antarctic 3 Artic 4 Antarctic Mammals Seabirds Mammals Seabirds Fishes 1 Polar Environments Unique set of characteristics not found in other marine environments Long winter night without sunlight It s cold Large areas perpetually or seasonally covered in ice Buffers water below from extreme conditions above Stable platform for life above water Barrier to access water below Typical polar animal Many are homeotherms warm bodied Large bodied insulated animals that undergo seasonal migrations Reproduction suited to cold Birth at time of year allowing fast growth of young Mating systems related to more scarce resources Birth Avoid extremely cold water by being born On ice out of cold water At lower latitudes out of cold water High energy investment by females few young large polar animals tend to breed closer to equator and feed closer to poles Large bodied