ocean life

marine food chains

Figure 14.29 shows a marine food chain. Phytoplankton form the base of the food chain. Phytoplankton are the most important primary producers in the ocean. They use sunlight and nutrients to make food by photosynthesis. Small zooplankton consume phytoplankton. Larger organisms eat the small zooplankton. Larger predators eat these consumers. In an unusual relationship, some enormous whales depend on plankton for their food. They filter tremendous amounts of these tiny creatures out of the water. The bacteria that make food from chemicals are also primary producers. These organisms do not do photosynthesis since there is no light at the vents. They do something called chemosynthesis. They break down chemicals to make food. When marine organisms die, decomposers break them down. This returns their nutrients to the water. The nutrients can be used again to make food. Decomposers in the oceans include bacteria and worms. Many live on the ocean floor. Do you know why?

textbook_image

benthos

Benthos are living things on the ocean floor. Many benthic organisms attach themselves to rocks and stay in one place. This protects them from crashing waves and other water movements. Some benthic organisms burrow into sediments for food or protection. Benthic animals may crawl over the ocean floor. Examples of benthos include clams and worms. Figure 14.27 shows two other examples. Some benthos live near vents on the deep ocean floor. Tubeworms are an example (see Figure 14.28). Scalding hot water pours out of the vents. The hot water contains chemicals that some specialized bacteria can use to make food. Tubeworms let the bacteria live inside them. The bacteria get protection and the tubeworms get some of the food.

textbook_image

textbook_image

nekton

Nekton are living things that swim through the water. They may live at any depth, in the photic or aphotic zone. Most nekton are fish, although some are mammals. Fish have fins and streamlined bodies to help them swim. Fish also have gills to take oxygen from the water. Figure 14.26 shows examples of nekton.

textbook_image

plankton

Plankton are living things that float in the water. Most plankton are too small to see with the unaided eye. Some examples are shown in Figure 14.25. Plankton are unable to move on their own. Ocean motions carry them along. There are two main types of plankton: 1. Phytoplankton are plant-like plankton. They make food by photosynthesis. They live in the photic zone. Most are algae. 2. Zooplankton are animal-like plankton. They feed on phytoplankton. They include tiny animals and fish larvae.

textbook_image

textbook_image

living things in the ocean

When you think of life in the ocean, do you think of fish? Actually, fish are not the most common life forms in the ocean. Plankton are the most common. Plankton make up one of three major groups of marine life. The other two groups are nekton and benthos. Figure 14.24 shows the three groups.

instructional diagrams

No diagram descriptions associated with this lesson

questions

The three major groups of marine organisms include

a. fish.

b. worms.

-->  c. plankton.

d. phytoplankton.

What type of organism found in the ocean floats along with the current?

-->  a. plankton

b. whales

c. jellyfish

d. squids

Most plankton are

a. able to swim.

-->  b. microscopic in size.

c. found in the aphotic zone.

d. able to move on their own.

What part of a fishs body extracts oxygen from the water?

a. bladder

-->  b. gills

c. spleen

d. lungs

All nekton

a. are fish.

-->  b. can swim.

c. live in the photic zone.

d. live in the aphotic zone.

Benthic organisms that live in the intertidal must do which of the following

a. have hard shells

b. have strong attachments

c. burrow into sediment

-->  d. any of these

Coral reefs

a. are found off of nearly all shorelines

b. are rocky outcroppings with little other life

-->  c. have a tremendous amount of biodiversity

d. none of these

Marine organisms that move by crawling are

a. nekton.

-->  b. benthos.

c. plankton.

d. zooplankton.

An example of a benthic organism is a

-->  a. sea anemone.

b. whale shark.

c. lion fish.

d. fish larva.

Life in the deepest ocean is

a. non-existent

b. abundant

c. about the same as at the surface

-->  d. scarce

Tubeworms obtain food from

a. algae.

-->  b. bacteria.

c. sediments.

d. phytoplankton.

The most important producers in the ocean are

a. plants.

b. bacteria.

c. zooplankton.

-->  d. phytoplankton.

Nekton must live in the photic zone.

a. true

-->  b. false

Zooplankton may include larvae of large animals.

-->  a. true

b. false

Plankton are organisms that can swim against the current.

a. true

-->  b. false

There is no photosynthesis at deep-sea vents because there is no light.

-->  a. true

b. false

If an ocean plant can photosynthesize, light must be available to the plant.

-->  a. true

b. false

All marine organisms are adapted to life in salt water.

-->  a. true

b. false

No marine organism can withstand the extreme water pressure at the bottom of the ocean.

a. true

-->  b. false

Fish are the most numerous life forms in the ocean.

a. true

-->  b. false

Plankton range in size from bacteria to whales.

a. true

-->  b. false

Plankton always remain in one place because they cannot swim.

a. true

-->  b. false

Zooplankton feed on phytoplankton.

-->  a. true

b. false

Some nekton are mammals.

-->  a. true

b. false

Fish swim with their fins and gills.

a. true

-->  b. false

Many benthic organisms attach themselves to rocks.

-->  a. true

b. false

Sea cucumbers live on the ocean floor.

-->  a. true

b. false

marine organisms that swim

a. benthos

-->  b. nekton

c. phytoplankton

d. plankton

e. zooplankton

f. alga

g. fish larva

example of zooplankton

a. benthos

b. nekton

c. phytoplankton

d. plankton

e. zooplankton

f. alga

-->  g. fish larva

name for plant-like plankton

a. benthos

b. nekton

-->  c. phytoplankton

d. plankton

e. zooplankton

f. alga

g. fish larva

name for animal-like plankton

a. benthos

b. nekton

c. phytoplankton

d. plankton

-->  e. zooplankton

f. alga

g. fish larva

general term for marine organisms that float on water

a. benthos

b. nekton

c. phytoplankton

-->  d. plankton

e. zooplankton

f. alga

g. fish larva

organisms that live on the ocean floor

-->  a. benthos

b. nekton

c. phytoplankton

d. plankton

e. zooplankton

f. alga

g. fish larva

example of phytoplankton

a. benthos

b. nekton

c. phytoplankton

d. plankton

e. zooplankton

-->  f. alga

g. fish larva

diagram questions

No diagram questions associated with this lesson