. A textbook in general zoology. Zoology. STARFISH, SEA URCHIN, BRITTLE STARS 99 A characteristic feature of the sea cucumbers is the much- branched tentacles about the mouth (Fig. 51). The tentacles vary in number from eight to twenty and some- times more. These are supposed to be much-moflified tube feet, and are used to push food into the mouth. When the animal is disturbed, they can be greatly contracted and drawn completely back within the mouth. Sea cucumbers vary from two to fifteen inches in length, depending upon the species and the age of the incUvidual. One species of Cucumaria some
. A textbook in general zoology. Zoology. STARFISH, SEA URCHIN, BRITTLE STARS 99 A characteristic feature of the sea cucumbers is the much- branched tentacles about the mouth (Fig. 51). The tentacles vary in number from eight to twenty and some- times more. These are supposed to be much-moflified tube feet, and are used to push food into the mouth. When the animal is disturbed, they can be greatly contracted and drawn completely back within the mouth. Sea cucumbers vary from two to fifteen inches in length, depending upon the species and the age of the incUvidual. One species of Cucumaria sometimes attains a length of three feet and is orange-red in color. Feather stars. — This group of echino- tlerms comprises the lowest representa- tives and at the same time the oldest members of the branch. The feather stars, crinoids, or sea lilies as they are variously calletl, are found as fossils in the rocks of the paleozoic age and were very abimdant in the past. The living forms are few and, for the most part, inhabit the deeper regions of the sea. It is a characteristic of the crinoids that they are attached to objects in the sea, Fig. 52.—Se.^hiy. either for a short period of their life, or permanently. Most of the species are permanently attached to submarine objects by a stem, which frequently is very long, and made up of a series of joints perforated by a central canal. The body (Fig. 52), borne on the end of the stalk, has the oral side uppermost, which position, it will be recalled, is. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Herrick, Glenn W. (Glenn Washington), 1870-1965. New York, Cincinnati [etc. ] American Book Company
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