“Ocean-lamps,” too, many may with truth be named. Large numbers of the coral-polyps, large numbers of the hydroids, and perhaps all of the free-swimming medusæ or jelly-fishes, carry with them their own little lanterns, wherewith at night to make bright the surface of the sea—wherewith also to bear glimmers of light downward into those black depths where sunlight cannot reach.
That Jelly-fish which “swam in a tropical sea,” and said, “This world it consists of ME!” must have been an unusually intelligent specimen of its kind. Jelly-fishes in general are not credited with even much bodily sensation, far less with mental originality.
Coral-polyps have had their meed of attention in an earlier chapter. There is a near relationship between the reef-builders of equatorial seas and the anemones of British sea-beaches. But the anemone is a creature of distinctly higher development than the co-operative coral-polyp. It has at least the great gift of individuality, which its reef-cousins have not.
Sea-anemones have been compared to garden asters, and indeed the resemblance is not slight. The living tentacles of the one might almost be taken for a rough copy of the thick petals of the other.
In general form sea-anemones are round soft disc-like bodies, surrounded or trimmed by a border of fleshy tentacles, and mounted on a thick fleshy stalk or cylinder, which is usually either fastened to a rock or buried in the sand.
They vary in size between half-an-inch and more than a foot in diameter. A splendid specimen, to be found in the Pacific, is fourteen inches across the disc.
These creatures are not without a limited power of moving from place to place; though, in the case of most “attached” anemones, movement is extremely slow. A few kinds do not attach themselves at all, but rove freely through ocean-waters, after the fashion of their cousins the jelly-fishes.
One particular species, which seems to approve of change of scene, and yet not to love exertion, has hit upon a clever dodge.
When quite young it fixes itself upon the shell of a certain kind of crab; and as it grows larger, it gradually covers the whole back of the crab. Where the crab goes, the anemone goes; when the crab rests, the anemone rests. Oddly enough, the crab does not appear to object to his burden.
This is no mere accidental comradeship, seen only in rare cases; for that special description of crab is never seen without its friend the anemone perched confidingly upon its back; and that special description of anemone is never seen without its friend the crab for a steed.