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Life in the Ocean’s Depths Survival in the Deep Sea • Sunlight fades with increased depth • Tremendous pressure of ocean depths –1 atm at sea level –Increase by 1 atm every 10 m Adaptations to Pressure • Fluid pressure in animal tissue matches the pressure of the surrounding water • Tissue fluid pressure pushes against the surrounding pressure with an equal but opposite force – Prevents them from being crushed Adaptations to Cold • Body temperatures close to temperature of the surrounding water – Slow metabolism • • • • • Move more slowly Grow more slowly Reproduce less frequently and later in life Live longer than similar species in surface water Require less food • Body densities close to density of their environment – Do not have to expend energy to keep from sinking Life in the Dark • Color in organisms: – Disphotic or twilight zone: • 150-450m below surface • Enough light to make countershading a means of camouflage • Ex: hatchet fish – Possess rows of photophores along bodies (lightproducing organs) » Aid in species recognition » Camouflage Role of Bioluminescence • Common in animals found between 300-2400m – Some have bioluminescent organs (ex: squid, crustaceans, fish) – Some have bioluminescent bacteria in species-specific locations (mutualism) • Occurs when a protein (luciferin) is combined with oxygen in the presence of an enzyme (luciferase) and ATP – Chemical energy of ATP is converted into light energy • Camouflage: –Will not appear as a shadow or silhouette when seen from below • Mating and species recognition: – Pattern of lights identifies species or individuals as male or female – Signal readiness to mate by series of light flashes • Attracting prey: –Bioluminescent lures and eyes • Defense: –Bioluminescent fluid that clouds the water with light • Confuses predators Seeing in the Dark • Eyes of many deep-sea fishes are tubular and have 2 retinas versus 1 – One retina views distant objects – Other sees closer things • Better depth perception • Some have tiny eyes (slightly functional) or are blind and must rely on tactile or chemical stimuli Finding Mates in the Dark • Male bites female and remains attached, sometimes for life (ex: anglerfish) –Lifelong parasite (fuses to female) Finding Food in the Dark • Scarce in the deep sea – No photosynthetic organisms – Detritus from above • Barbel – Fleshy projection that dangles below chin or throat – Lures to probe the bottom ooze for food – Can serve in species recognition during mating Giants of the Deep • Live longer than shallow water relatives • Giant squid (Architeuthis) – Largest of all invertebrates (9-16m long) • Arms thick as human thigh and covered with thousands of suckers – Capture prey and carry it to animal’s beak where it is shredded to pieces – Found in all oceans 600 ft. or more – Anatomy indicates weak swimmers – Unknown diet – Hunted and eaten by sperm whales Relicts From the Deep Many species have undergone little evolutionary change • Spirula – Mollusk with spiral internal shell of gasfilled chambers – Resemble squids and octopuses • Vampire squid – Webbing between the arms – Dark color – Muscles are soft and poorly developed – Spend entire lives in deep water – Good eyesight – Bioluminescent organs • Coelocanth – 1.8 m (6 ft.) long – Large, thick scales and fleshy bundles between its body and fins • Neopilina –Limpet-like mollusk –Lightweight conical shell –Large pink and blue foot Life on the Sea Bottom • Benthic communities: – Must deal with extreme pressures, low temperatures, and darkness – Impacted greatest by food availability – Sources of food: • Feces • Decaying tissue • Organic matter – Food chains • Bacteria meiofauna (ex: foraminiferans, nematodes) large worms and bivalves • Vent communities: – Can be very productive – Can exist without solar energy – Not all surround hydrothermal vents • Vent formation: – Form at spreading centers – Cold seawater seeps down near centers through cracks and fissures in ocean floor • Comes into contact with hot basaltic magma – Superheated water returns to the sea through chimney-like structures formed by minerals that have precipitated out of hot water 2 Types of Chimneys • White smokers – Produce stream of milky fluid rich in zinc sulfide – Temperature less than 300°C • Black smokers – Narrow chimneys – Emit clear water with temperatures between 300-450°C rich in copper sulfides • Encounters cold ocean water and sulfides precipitate, producing black color • Organisms: – Large clams, mussels, anemones, barnacles, limpets, crabs, worms, and fishes – Large worms (10 feet long) – Primary producers are chemosynthetic bacteria • Oxidize compounds such as hydrogen sulfide – Small animals feed directly on bacteria or can absorb organic molecules released by bacteria when they die • Rise and fall or vent communities – Last about 20 years until vents become inactive