A sea-anemone, like a coral-polyp, has a mouth and a stomach. But unlike the coral-polyp, it has the mouth and stomach for its own use, not merely in trust for the benefit of the whole community.
When the pretty flower-like creature wishes to open itself out, it takes in a quantity of salt water. When it wishes to shut itself up, it spurts the water out, drawing its tentacles close.
Both mouth and stomach are elastic; and it is able to swallow animals that are very little smaller than itself. Sometimes it gulps up greedily a whole crab or bivalve, digesting the soft animal parts, and getting rid of the useless shell as easily as it gets rid of water, when about to close.
Soft and mild and helpless as a sea-anemone may seem, it is really far from being defenceless.
Within that plump body, around the mouth, in the skin, about the tentacles, and along the slender hanging white cords, lie concealed thousands, even millions, of weapons. Each weapon is a very fine and delicate thread of hollow make, curled tightly up in a minute cell, ready for use. When a sea-anemone desires to injure or to kill, either in defence or in attack, it darts out a number of these little “lassos” as they are called.
Each lasso is not merely unwound, but is actually turned inside out, as you may turn a stocking inside out, when drawing it off. And as the instantaneous process takes place, poison flows with the tiny dart into the wound that is made. Small though each lasso may be, when dozens or hundreds of them are launched together, the result is not contemptible, even as regards man; and ocean creatures die fast from the poison.
A cell which contains a lasso is about one five-thousandth of an inch across; and two hundred lassos, placed end to end, would reach to about an inch in length. When once a lasso has been darted forth, it can never again be used, because it cannot be returned to the cell. But so great are the supplies of them, that a sea-anemone never gets to the end of its armoury. Even if all were used, others would speedily grow in their place.
Some kinds of animals, living in the sea and of service to man, are in danger of being thinned out of existence by the incessant ravages of net and trawl, of hook and harpoon. Not so the world of Anemones. So vast are their numbers, so rapid is their increase, that no antagonistic forces can annihilate them.
It has been said that if every anemone on British shores were one day swept away, carried off by an army of ardent naturalists, or destroyed by waves in some tremendous tempest, the next inflowing tide would bring a fresh supply, sufficient to fill all gaps.
Not less numerous, perhaps far more numerous, are the countless hordes of Jelly-fishes, so called, though they are not fishes—of Sea-nettles, so called, though they are not nettles.