Download Chapter 18: Life in the Ocean*s Depths

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