MEDUSA.
Before noticing the wonderful way in which this animal finds its dinner, let us look at its body. In any large Jelly-fish you can see marks which run from the centre of the body, and another mark round the edge of the "umbrella." These are really tubes. They all join with a hollow space inside the body, which is the creature's stomach. The mouth-tube opens under the body, as can be seen by turning the Jelly-fish on its back, and moving the lobes of jelly aside. All the food goes up this tube-mouth, and so into the stomach of the animal. The whole creature is little more than so many cells of sea-water, the walls of the cells being a very thin, transparent kind of skin.
Perhaps the strangest thing about it is the way in which it catches prey. Jelly-fish feed on all kinds of tiny sea animals, such as baby fish, and the young of crabs, shrimps, and prawns. These small creatures form part of the usual dinner of many a hungry dweller in the sea, and the Jelly-fish takes a share of them.
A MEDUSOID.
From the edge of the "umbrella" there hangs a fringe of long, delicate hairs, rather like spiders' threads. These are fishing lines, yet much more deadly. They trail through the water, stretching far from the main part of the Jelly-fish; and any small creature unlucky enough to touch them is doomed.
Down each one of these threads there are minute cells, hundreds and hundreds to every thread; and in each cell there is a dart, coiled up like the spring of a watch. The tip of the dart is barbed like a fishhook. Now the cells are so made that they fly open when touched. The dart then leaps out and buries itself in the skin of the animal which touched the thread. Not only that, but the darts are poisoned, and soon kill the small creatures which they pierce.
You see now how this innocent-looking Jelly-fish gets its food. As it swims along, the threads touch the tiny living things in the sea, the darts pierce them and poison them. Of course these stinging darts are very, very small, much too small for our eyes to see.