The littoral area as defined is not a large haunt of life; it occupies
only about 9 million square miles, a small fraction of the 197,000,000
of the whole earth's surface. But it is a very long haunt, some 150,000
miles, winding in and out by bay and fiord, estuary and creek. Where
deep water comes close to cliffs there may be no shore at all; in other
places the relatively shallow water, with seaweeds growing over the
bottom, may extend outwards for miles. The nature of the shore varies
greatly according to the nature of the rocks, according to what the
streams bring down from inland, and according to the jetsam that is
brought in by the tides. The shore is a changeful place; there is, in
the upper reaches, a striking difference between "tide in" and "tide
out"; there are vicissitudes due to storms, to freshwater floods, to
wind-blown sand, and to slow changes of level, up and down. The shore 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._