Download NOTES Ocean Life

OCEAN LIFE
Classification of Marine Organisms:
1. Plankton – all organisms that drift with tides and currents
 Bacteria, protists, algae
 Not a species – include many different types of
organisms. Describes a lifestyle.
 Phytoplankton – capable of photosynthesis – most
important primary producers
 80% of Earth’s O2 production occurs here
 92% of Ocean’s primary productivity (others –
seaweed and chemosynthesis)
 Diatoms – made of silica
 Dinoflagellates, coccolithophores
 Zooplankton – animal-like protists incapable of
photosynthesis- feed on phytoplankton
 Radiolarians, jellyfish
2. Nekton – all aquatic animals capable of movement independent of
the tides and currents
 Sharks, fish, dolphins, whales
3. Benthos – those animals living on or in the ocean bottom (seaweed,
sea stars, crabs)
 Foraminifera (some are planktonic) – secrete
calcium carbonate tests (external shells)
 Sponges, sea anemones, sea fans, lobsters, clams,
oysters, sea urchins, shrimp
Marine Life Zones
Factors: available sunlight, distance from shore, depth of water,
temperature, nutrients
A. Pelagic zone – water portion
 open ocean of any depth where animals swim or float
 Contains both photic and aphotic zones
 Contains both neritic and oceanic zones
1. Neritic zone – from the low tide mark to the gently sloping
continental shelf
 Found entirely in the photic zone with sunlight reaching
the ocean floor
 Richest in biomass – supports approx. 90% of the world’s
fishing industry
2. Oceanic zone – open ocean past the continental shelf
 Significantly less biomass even in the photic zone
B. Benthic zone – bottom – from shoreline to deep ocean
 98% of marine species are found in or near the ocean
floor
 bottom dwelling species regardless of distance from the shore
 supralittoral – water splash, does not remain
submerged
 littoral (intertidal) - area between high and low
tide, area of constant change (O2, sunlight, water
coverage, sediment), rich diversity of marine life due
to large quantity of food available
 sublittoral – ocean bottom close to shore
 bathyal – bottom along continental slope down to
deep ocean bottom
 abyssal zone – deep ocean bottom, very low
temps, high pressures, no light. Hydrothermal vents
located here. These areas are rich in sea life as
heat from the Earth’s mantle adds nutrients and
energy. Energy provide by chemosynthesis.
 hadal zone – below 6000 m
1. Photic zone – area that receives sunlight
 Euphotic zone – “good light” (surface to ~ 200 m.)
nearest the surface with strongest light intensity –
enough for photosynthesis
o Phytoplankton are the primary producers here
 Dysphotic zone (200 – 900 m) – “bad light”
o Small fish, squid, shellfish
o Spend daylight here and rise to near surface
to feed off zooplankton and phytoplankton at
night to avoid predators
o Have large eyes and phosphorescence that
makes them glow in the dark.
2. Aphotic zone – “without light” (below ~ 900 m.)
 Since light cannot penetrate here, the energy
source for this zone is organic matter that drifts
down from above.
 Most organisms are scavengers or detritivores.
Some microorganisms use chemosynthesis to
produce biomass.
2
 Pressure here is several tons per in .
 Temperature not greater than 3°C (37F)
 Organisms generally prey on each other – large,
gaping mouths and large, sharp teeth
Heterotrophs cannot make their own food and must obtain it from
their surroundings. (Consumers)
Autotrophs – can make their own food (plants) (Producers)
2.5 billion years ago, Autotrophs (animals that make their own food –
photosynthesize) changed the composition of the atmosphere from less than 1%
oxygen to the level it is today – 20%
Marine Food Web (in the photic zone)
Phytoplankton → Zooplankton → secondary consumers
(sardines, herring, tuna) → tertiary consumers (toothed whales,
sharks)
INVERTEBRATES
 are generally soft-bodied animals that lack a rigid internal
skeleton
Cnidarians take their name from the large stinging cells called
cnidoblasts
 Jellyfish, sea anemones, corals
 9000 species worldwide
 Simplest of the “higher” organisms – but most beautiful!
 Radial symmetry
 Two body shapes: polypoid and medusoid.
Arthropods (crustaceans – ocean arthropods) – most successful
of Earth’s animal phyla – 1 million species
 Segmented bodies, jointed legs, exoskeleton
 Barnacles, krill, shrimp, crab, lobster
Echinoderms –
 unique water-vascular system of water-filled canals, valves and
projections for locomotion and feeding
 starfish, sea urchins, feather stars, sand dollars, sea
cucumbers, brittle stars
Mollusks  Squids, octopuses, snails, sea slugs, oysters, clams, conches
 50,000 species
VERTEBRATES
Fish Most fishes are cold-blooded (ectothermic)
 Most actively-swimming fishes are streamlined and some
secrete friction-reducing mucus or oil.
 Fish take in water containing dissolved oxygen at the mouth
and pump it past fine gill membranes and the water exits
through the rear-facing gill slits.
 Schooling behavior confuses predators which can have
difficulty selecting one fish from the swirling mass
 Grouper, tuna, halibut, eels, angelfish
 Class Chondrichthys – cartilage (not true bones) – sharks, rays
Reptiles –
 Lungs, scales, internally fertilized eggs
 Sea Turtles - skilled navigators, they return to their home
beaches for decades
 Sea snakes, marine iguanas,
True seabirds  generally avoid land unless they are breeding. They get all
their food from the sea and seek isolated areas for
reproduction.
 Albatrosses can cover great distances searching for food, flying
continuously for weeks or months at a time.
 Penguins lost the ability to fly. They are excellent swimmers
with great maneuverability.
Marine mammals  warm-blooded (endothermic)
 They do not have to drink fresh water due to osmotic
adaptations.
 Mysticete whales are the largest animals ever to have lived on
Earth
 Toothed whales search for prey using echolocation, the
biological equivalent of sonar.
 Pinnipeds – seals (no ear flaps) and sea lions (have ear flaps)
Habitat – an organism’s “address” within its community, its physical
location.
Niche – an organism’s “occupation” within its habitat. Its relationship
to food and enemies.
Estuaries – serve as marine nurseries, protecting oceanic species
for a few weeks or months before they venture to sea. Birds also
nest in these areas.
Coral reefs – most diverse communities
Radially symmetrical organisms are round and have no right or left
sides.
Only a few sharks are dangerous to humans. Stings by jellies kill
more people.