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Updated: May 28, 2025
They swell in the water, until the yellowish bundle is three times as large as the Whelk that laid it. You often see the empty bundle blown by the wind along the shore. Give the names of two bi-valve molluscs. What is the Periwinkle's shell made of? Describe how the Periwinkle eats seaweed. How does the Whelk obtain its food? Give the names of three one-shelled molluscs.
Its agitated demonstrations whatever their vital purpose may be to the superficial observer are danger signals, a means of self-preservation, as a substitute for the hard calcareous armour bestowed upon other molluscs. The fussy red rays may impose upon enemies a sense of discretion which constrains them to avoid the lima, which, though hostile in appearance, is one of the mildest of creatures.
Almost all the leaves, excepting those that float on the surface, are so thickly incrusted with corallines as to be of a white colour. We find exquisitely delicate structures, some inhabited by simple hydra-like polypi, others by more organized kinds, and beautiful compound Ascidiae. On the leaves, also, various patelliform shells, Trochi, uncovered molluscs, and some bivalves are attached.
The Helix ianthina, which is included by certain writers among the molluscs employed for dyeing purposes by the Phoenicians, is a shell of a completely different character, smooth and delicate, much resembling that of an ordinary land snail, and small compared to the others.
The ridges and furrows of the cyclone season, when the clean sand is covered and stained with weed, dead and living molluscs, coral, leaves carried from the hills by flooded streams, all fermenting in the heat, tell that Christmas is past and March not yet over. Many a year passes without such a storm as compels the groaning ocean to ravage its reefs.
This brought the lecturer to the great ladder of animal life, beginning low down in molluscs and feeble sea creatures, then up rung by rung through reptiles and fishes, till at last we came to a kangaroo-rat, a creature which brought forth its young alive, the direct ancestor of all mammals, and presumably, therefore, of everyone in the audience. But had the process stopped?
It has an enormous head hence one of its names, Loggerhead duck with a hard powerful beak for smashing open the shells of molluscs, which form its principal food. Its wings are so short and weak that flight in the air is denied it.
At certain points along the shores of nearly all the Danish islands, mounds may be seen, consisting chiefly of thousands of cast-away shells of the oyster, cockle, and other molluscs of the same species as those which are now eaten by Man.
These are the cuttle fish, which have now surrendered their Aristotelian name of 'molluscs' to that greater group which is seen to include them, together with the shell-fish or 'ostracoderma' of Aristotle. These cuttle-fishes are creatures that we seldom see, but in the Mediterranean they are an article of food and many kinds are known to the fishermen.
The Brachiopods have passed into entirely new and more advanced species in the many advances and retreats of the shores, but the Molluscs show more interesting progress. The commanding group from the start is that of the Molluscs which have "kept their head," the Cephalopods, and their large shells show a most instructive evolution.
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