re is
a very crowded haunt, for it is comparatively narrow, and every niche
among the rocks may be precious.

[Illustration: AN EIGHT-ARMED CUTTLEFISH OR OCTOPUS ATTACKING A SMALL
CRAB

These molluscs are particularly fond of crustaceans, which they crunch
with their parrot's beak-like jaws. Their salivary juice has a
paralysing effect on their prey. To one side, below the eye, may be seen
the funnel through which water is very forcibly ejected in the process
of locomotion.]

[Illustration: A COMMON STARFISH, WHICH HAS LOST THREE ARMS AND IS
REGROWING THEM

The lowest arm is being regrown double.

(_After Professor W. C. McIntosh._)]

[Illustration: A PHOTOGRAPH SHOWING A STARFISH (_Asterias Forreri_)
WHICH HAS CAPTURED A LARGE FISH

The suctorial tube-feet are seen gripping the fish firmly. (After an
observation on the Californian coast.)]

[Illustration: _Photo: J. J. Ward, F.E.S._

THE PAPER NAUTILUS (ARGONAUTA), AN ANIMAL OF THE OPEN SEA

The delicate shell is made by the female only, and is used as a shelter
for the eggs and young ones. It is secreted by two of the arms, not by
the mantle as other mollusc shells are. It is a single-chambered shell,
very different from that of the Pearly Nautilus.]

Keen Struggle for Existence

It follows that the shore must be the scene of a keen struggle for
existence--which includes all the answers-back that living creatures
make to environing difficulties and limitations. There is struggle for
food, accentuated by the fact that small items tend to be swept away by
the outgoing tide or to sink down the slope to deep water. Apart from
direct competition, e.g. between hungry hermit-crabs, it often involves
hard work to get a meal. This is true even of apparently sluggish
creatures. Thus the Crumb-of-Bread Sponge, or any other seashore sponge,
has to lash large quantities of water through the intricate canal system
of its body before it can get a sufficient supply of the microscopic
organisms and organic particles on which it feeds. An index of the
intensity of the struggle for food is afforded by the nutritive chains
which bind animals together. The shore is almost noisy with the
conjugation of the verb to eat in its many tenses. One pound of rock-cod
requires for its formation ten pounds of whelk; one pound of whelk
requires ten pounds of sea-worms; and one pound of worms requires ten
pounds of sea-dust. Such is the circulation of matter, ever passing from
one e