Life in the Ocean
Beth Roland
Eighth Grade Science
Three Groups of Marine Life
• The three groups of
marine life are
plankton, nekton, and
benthos.
• Aquatic life in the
ocean is divided
based on where an
organism lives and
how it moves.
Marine Life
plankton
Nekton
benthos
Plankton
• Organisms that float or
drift freely near the
ocean’s surface are
called plankton.
• Often microscopic,
plankton are an important
food source for many
organisms
– Phytoplankton- plant-like
plankton that can
photosynthesize
– Zooplankton- animal-like
Nekton
• Nekton are organisms
that swim freely in the
open ocean.
• Examples include
mammals such as
whales and dolphins,
sea lions as well as a
great variety of fish
Benthos Organisms
• Benthos are
organisms that live in
or on the ocean floor
• Examples include:
crabs, starfish, worms
coral, sponges,
seaweed and clams
Food Chain vs. Food Web
• Food Chains show a
linear path from one
animal to another
• Very simplistic and can
be easily understood
• Food Webs show various
organisms that are eaten
by other organisms
• Allows one to see the
interconnectedness of
species and how they
depend on one another
for survival
• Show energy transfer
among many feeding
levels
Food Chains vs. Webs continues
EXAMPLE:
GRASS (is eaten by a) GRASSHOPPER
(which is eaten by) a FROG (which is
eaten by a) SNAKE (which is eaten by
a) HAWK
EXAMPLE:
TREES produce acorns which act as food
for many MICE and INSECTS. Because
there are many MICE, the WEASELS,
SNAKES, and RACOONS, have food. The
insects in the acorns also attract BIRDS,
SKUNKS, and OPOSSUMS. With the
SKUNKS, OPPOSUMS, WEASELS and
MICE around, HAWKS, FOXES, and OWLS
can find food. They are all connected!
Terrestrial and Aquatic
Relationship
Marine Environments
Marine Environments
classified by:
-water depth and
-ability of sunlight to
penetrate
Intertidal Zone
location where ocean
meets the land
-area is exposed for
part of the day
organisms adapted to
exposure to air/
survive crashing
waves
Neritic Zone along the
continental shelf and
slope, temperature is warm
Ex: corals, sea turtles,
fishes, and dolphins
Oceanic Zone floor drops
sharply, deep water
Ex. fishes, whales, and
sharks
Benthic Zone located at the
ocean floor. No sunlight
penetrates, extremely cold
Ex. fishes, worms and crabs
Organisms often live around
hydrothermal vents