Snails, clams, mussels, and even octopuses are
all molluscs – soft-bodied animals that often have
strong chalky shells. Some live on land, but most
molluscs live underwater or on tidal seashores. A snail or
octopus can move about and use its sense organs to find
food, but many aquatic molluscs, such as mussels, spend
their adult lives in one place. They do not have obvious
sense organs or even heads, and their bodies are encased
within two shells that can be closed for protection.Molluscs
(^1) Snail Able to creep about on its muscular
foot, a snail can squeeze its soft, boneless body
into its coiled shell when it feels threatened.
(^2) Giant snail A native of tropical Africa,
the giant snail can be 30 cm (12 in) long.
A gland at the front of the foot produces
the slime that enables a snail to slide along.
(^3) Giant clam The biggest of all molluscs, the
giant clam can grow to more than 1 m (3.25 ft)
across. It finds a spot in a coral reef and, once
there, stays in place for life.
(^4) Squid Fast-swimming squid can catch fish
with their tentacles, change colour, and shoot
through water backwards using jet propulsion.
(^5) Slug Basically snails without shells, slugs
can live in places with few of the chalky
minerals that other molluscs need to build
up their shells as they grow larger.
(^6) Limpet Able to clamp its strong shell to
rocks, the limpet is well equipped to survive
the rough and tumble of rocky seashores.
3
4
5
2
1
9
8
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Whelks grow their shells
from chalky deposits
extracted from sea water
Eye at tip of
snail’s tentacle
Squid’s head end
has eight arms
and two tentacles Squid can swim
faster than any
other invertebrate
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