Childrens Illustrated Encyclopedia

469

Slime

Snails and slugs

make several types of

slime. As the slug crawls

along, it lays down one

kind of slime in patches.

Another kind of slime is

given off when the creature

is attacked by a predator.

A slug crawls by waves of muscle

contractions passing along its foot.

GArden SnAil

The snail’s shell protects the animal from predators and prevents

the soft, moist body from drying out. The shell is made of calcium

carbonate and other minerals. As the snail grows, it adds more

material to the mouth of the shell, making it larger. The snail’s

tongue is called a radula. it is small and filelike, with as many

as 150,000 toothlike denticles for rasping at plant food.

Diameter of

shell increases

as snail

grows.

SlimY, SlOW-mOVinG SnAilS and slugs belong to a group of

creatures called gastropods, meaning “stomach foot.” These animals

seem to glide along on their stomachs; in fact, the underside is

itself a special organ that produces movement. There are about

65,000 kinds of slugs and snails, all belonging to the larger

group of animals called mollusks, a group that also includes

clams and octopuses. in addition to the familiar land snails

and slugs, there are marine gastropods, such as sea slugs, sea

hares, winkles, limpets, and freshwater species, such as pond

snails, and ramshorn snails. Slugs and snails are

similar in shape. Snails have shells to

protect their bodies; most slugs have

no shells. Both have antennae on their

heads, with eyes on the ends of the

antennae. Snails and slugs are

hermaphrodites. This means that

they have both male and female reproductive

organs. most slugs and snails hide away and

hibernate during the cold or dry season.

during hibernation, snails seal the mouth

of their shell with a film of dried mucus.

YOUnG

After mating, the snail or slug lays

eggs, either singly or in batches,

in mucus. The young snails

and slugs hatch from

their eggs after

about two to

four weeks.

Mantle, the fold of flesh

that envelops the body

Lip or mouth

of shell

Dark band on

edge of shell

SeA SlUG

There are many beautifully

colored sea slugs in the

shallow coastal waters

of the world, particularly

around coral reefs. many

have feathery or tufted gills

for absorbing oxygen from

the water. Sea slugs are

predators, feeding mainly

on sponges, barnacles, sea

mats, and sea anemones.

Lower surface

or foot

SlUG

Slugs are unpopular with gardeners

because some do serious damage to

plants and vegetables. most slugs have no

shells; some have a very small shell embedded

in the back. Slugs avoid drying

out by living in damp places

and emerging only at night

or after rain.

TOpShell

The purple

topshell snail

lives close to the

high-tide mark.

Sensory

antennae

Find out more

Ocean wildlife

Seashore wildlife

Shells and shellfish

SNAILS ANd SLUGS

Eyes on tips

of rear pair of

antennae

Mouth with

rasping tongue

(radula)

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