. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. Starfish, showing regeneration of lost arms. Notice that in the lowest specimen the arm is just begin- ning to regenerate. Regeneration. — It is no uncommon thing to find starfish with fewer arms than the normal number. In such specimens small arms are frequently seen, making it appear likely that, once having lost an arm, it might grow again. Such is indeed the case, the starfish having the ability to re- generate (grow anew) lost parts. If a star- fish should lose all five rays, it is pos
. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. Starfish, showing regeneration of lost arms. Notice that in the lowest specimen the arm is just begin- ning to regenerate. Regeneration. — It is no uncommon thing to find starfish with fewer arms than the normal number. In such specimens small arms are frequently seen, making it appear likely that, once having lost an arm, it might grow again. Such is indeed the case, the starfish having the ability to re- generate (grow anew) lost parts. If a star- fish should lose all five rays, it is possible that under favorable conditions it might regenerate all its lost parts and become as active as ever in the destruction of shellfish. Development. — Besides this asexual method of regeneration, the starfish repro- duces sexually by means of eggs and sperms. The sexes are separate. The eggs are passed into the water; fertilization takes place near the surface of the water, where the eggs and sperms are found in great numbers during the breeding season (June-July in Long Island Sound). Develop- ment proceeds at first as in the jellyfish, the egg segmenting to form a blastula and gastrula. Development does not proceed directly into a starfish, however, the animal being at first very unlike the adult. It swims freely until a limy skeleton is developed. The starfish larva eventually buds off a tiny star-shaped body which actually lives on the tissues of the larva, eventually becoming a tiny starfish no larger than a small pin head. At this stage of their existence they are foiuid on eelgrass and other salt-. Sea urchins (Arbacia) showing mouth, tube feet, and movable 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 Hunter, George William, 1873-1948. New York, American book company
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