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4 CLOSE UP

Tiny bristles on the front part of an

earthworm help it to grip the soil as it

moves. The worm propels itself forward by

elongating and contracting its body segments.

Parasites live on or inside other animals or

plants, called their hosts. They feed on the

blood or tissues of their host, or steal its

food. Some parasitic worms in people

survive without their host even noticing.

Others can cause serious diseases.

WHERE DO TAPEWORMS LIVE?

Tapeworms live in the guts of animals such as

pigs, cats, and humans. The host becomes

infected when it eats food containing

tapeworm eggs or young. Inside the gut, the

worm feeds on the host’s half-digested food.

As it matures, the worm produces

small packages of eggs, which

pass out of the victim’s body.

HOW DO LEECHES FEED?

Leeches use suckers on their head and tail to latch

on to animals, including humans, in order to suck

their blood. They inject a chemical that keeps the

host’s blood flowing freely. This lets them feed

until they are bloated, then they drop off. Leeches

lurk in ponds, streams, and other wet places.

4 CAT TAPEWORM

Tapeworms attach themselves to their host’s

intestines using hooks and suckers on their heads.

This species reaches 60 cm (2 ft) long. Some

tapeworms can grow up to 30 m (100 ft) long.

PARASITES

ROUNDWORM 3

These worms are also known as nematodes. Some

species contain more than 27 million eggs at any

time, and more than 200,000 in a single day.

Worms

Earthworms are the most familiar worms, but there

are thousands of other types of these soft, legless

creatures. Some are microscopic, others grow to

several metres long. Earthworms and roundworms are

tube-shaped. Flatworms are shaped like leaves or ribbons.

Tail is always

longer than

head end

Horny cuticle

protects the

body from

damage

Mucus

keeps the

body moist

Saddle

holds

fertilized

eggs after

mating

Segments

expand and

contract to help

the worm move

Hooks

fix on

to the

host’s

gut

Suckers

create a strong grip

WHERE DO WORMS LIVE?

Worms live on land and in water and can be found

in virtually every habitat on Earth. Earthworms live in

the soil. Leeches and bloodworms inhabit ponds and

rivers. Most ribbon worms and some flatworms live

in the oceans. Ragworms and lugworms are found on

the seashore. Some worms are. PARASITES

that live on or inside other animals.

HOW DO WORMS SENSE

THEIR SURROUNDINGS?

Some flatworms have very simple eyes - known

as eyespots - that can detect light, but most

worms are blind. Their most important sense is

touch. The earthworm’s skin picks up vibrations

caused by sounds or movements. Some predatory

worms have sensitive tentacles on their heads

that help them to capture their food.

4 EARTHWORM

Earthworms aerate and enrich

the soil as they burrow through

it. They feed on plants and

animals, or their rotting remains.

There are over 100,000 species of worm in three main phyla:

• Flatworms (includes turbellarians, tapeworms, and flukes)


• Segmented worms, or annelids (includes earthworms, lugworms,
  ragworms, and leeches)


• Roundworms (includes threadworms and pinworms)

WORM CLASSIFICATION

Anus

expels solid

waste

Mouth

sometimes

contains teeth

to grind food

POLYCLAD FLATWORM 1

Most non-parasitic flatworms

hunt or scavenge for food. Flatworms are a major

group of worms that includes tapeworms and flukes.

FIND OUT MORE. Ecology 80 • Invertebrates 102 • Soil 48

t’s

worms