Francis Arthur Bather

“ Starfish begin to eat voraciously when quite young; one less than 3/8th in. across has been observed to eat over fifty young clams of half that length in six days. The more a starfish has to eat the quicker it grows, and it may become sexually mature in less than a year, then producing many thousands of young. Fortunately the increase is kept in check by many causes. The young, while still in the stage of free-swimming larvae, are swallowed in millions by various fish. When they settle down on seaweed their bright colours attract eels and many small fishes. ”

“ At a later stage tangles of hemp or cotton waste may, be dragged over the oyster-beds, when the starfish will cling to them by their pedicellariae. They make excellent manure, but are of ho further service to man. Fishermen who catch them in their nets or on their lines often tear them in half and throw them back into the sea. Some of these mutilated animals may, however, grow fresh rays, and thus one may find a starfish consisting of one large ray and four quite small ones, the whole shaped like a comet. ”

“ But since the mouth is quite small and the food often large, the starfish finds it more convenient to turn its stomach inside out and to wrap it around the animal to be eaten, which is then digested quietly and the stomach withdrawn again. ”

“ Probably the best way in which man can keep down the numbers of starfish is by dredging the seaweed in the latter half of July when it is covered with young; a single cartload thrown on shore would capture many millions. ”

“ The stomach is not a long coil, but a simple sac with branched blind tubes extending into each ray. A generative gland also passes down the side of each ray, and emits the milt or eggs when ripe through a pore near the body. Spawning takes place in spring or early summer. ”

“ In the sand-stars the rays are comparatively short, with their spines closely pressed to their sides, so that they look like lizards’ tails; in the brittle-stars the rays are much longer and more flexible, with the spines standing out, so that they look like wriggling centipedes attached round a little sea-urchin. The brittle-stars are more active than the sand-stars, and can go more than two yards in a minute ”

“ Sand-stars and brittle-stars are found in all seas, usually occurring in quantities, but are most abundant in the rock-pools of the tropics. By constantly sweeping their arms over the sea bottom, they gather food consisting of minute animals. ”

“ The two former, which may often be found hiding under the rocks, or in the seaweed, or in pools at low tide, resemble the ordinary starfish in having five distinct arms. These, however, as shown in fig. 3, are long and serpent-like, and are attached to a relatively small body or disk. The digestive and generative systems do not extend to the rays but are confined to the body. The arms are cylindrical and have no groove on the under side such as exists in starfish ”

“ The axial ossicles, which correspond to the plates flooring the arm-groove in a starfish, resemble vertebrae connected by pairs of straight muscular bundles, and articulated by tenon-and-mortise joints, according to whose degree of development the arms vary in their power of coiling. ”