homework encyclopedia

82 Nature

HABITATS OCEANS

The oceans cover about 70 per cent

of the Earth’s surface and form

the largest of the world’s habitats.

Life is found at all depths, from

shallow surface waters to trenches

over 11 km (7 miles) down.

WHY ARE PHYTOPLANKTON IMPORTANT?

All ocean life depends on microscopic plant-

like organisms called phytoplankton.

Floating near the ocean’s surface,

phytoplankton trap sunlight energy to make

food. Zooplankton (tiny animals and protists)

feed on phytoplankton. They in turn provide

food for fish, crabs, squid, and other animals.

IS THERE LIGHT AT THE BOTTOM

OF THE OCEAN?

Light penetrates the ocean’s surface waters to

a depth of only about 200 m (656 ft). Below

this, in the twilight zone, it is much dimmer.

In the abyssal and hadal zone, it is pitch black,

and very cold. Each zone, down to the seabed,

has its own community of living things.

WHAT IS THE DIFFERENCE

BETWEEN A HOME AND A HABITAT?

A habitat is an area occupied by many

species. A home is a place within a habitat

where a particular animal species can protect

itself and its young from the weather and

predators. Homes include nests built by birds

and wasps, and burrows dug by moles.

WHAT IS A MICROHABITAT?

A small part of a habitat that has its own

conditions of, for example, temperature

and light, and its own characteristic species,

is called a microhabitat. Microhabitats

include the shady area under a tree and

the underside of a rock in a stream.

1 CHEVRONED BARRACUDA

A school of chevroned barracuda swim in surface waters off

Borneo, Malaysia. These fierce hunters round up other fish

and kill them with a snapping bite of their powerful jaws.

1 RACCOONS

North American raccoons are successful because they can

live in many habitats and eat anything. They even live in

towns and cities, where they survive by raiding rubbish bins.

Bromeliads grow on tree

branches, high up in

rainforest canopies – they

thrive in the moist air

Frogs lay their eggs in

bromeliad waterpools.

The tadpoles then feed

and grow in the pools

1 BROMELIAD MICROHABITAT

The red leaves of this tropical forest bromeliad hold a small

pool of water. The pool is a microhabitat in which frogs,

mosquito larvae, and other organisms can live.

Organisms are adapted to live in particular surroundings with

distinctive conditions, such as rainfall and temperature. This

is their habitat. The largest habitats include. OCEANS,

. WETLANDS,. FORESTS,. GRASSLANDS,. DESERTS,
. MOUNTAINS, and. POLAR HABITATS.

Habitats