Identifier: introductiontozo00dave Title:
Introduction to zoology; a guide to the study of animals, for the use of secondary schools; Year:
1900 (
1900s) Authors:
Davenport, Charles Benedict, 1866-1944 Davenport, Gertrude Anna Crotty, 1866- Subjects:
Zoology Publisher:
New York, Macmillan company London, Macmillian and co., ltd. Contributing Library:
MBLWHOI Library Digitizing Sponsor:
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view book online to see this illustration in context in a browseable online version of this book. Text Appearing Before Image: FKJ. 185. — Strongylocentrotus, the Eastern green sea-urchin, with tube feetextended. From Standard Natural History. waters, from low tide to one hundred fathoms, and areoften brought up by fishermen, to whose lines they have ahabit of clinging. The branching of the arms enables theanimal to hold its prey, which consists of shrimp and fish.The Echinoids, or sea-urchins, may be regarded as star-fishes in which the arms have shortened and the disk en-larged so as to fill up the interspaces, and make a solid, 200 ZOOLOGY nearly spherical form. The sea-urchins eat various smallanimals, and get food also from small bits of organic matterin the mud which they swallow. They live more concealedthan the starfish, for some burrow in the mud and others-such as our green sea-urchin of the Maine coast (Fig.185) — grind out pockets in the rocks by means of theirspines. Others cover themselves with seaweed, and thusbecome inconspicuous. Besides the green sea-urchin, Text Appearing After Image: FIG. 186. — Arbacia, the Easteru black sea-urchin. Tube feet retracted. Nat. size. Photo, by W. H. C. P. which is found north of Cape Cod, we have a black sea-urchin (Arbacia, Fig. 186), which extends south as far asNorth Carolina. We have on the east coast also two kindsof flat sea-urchins (sand-dollars), which live in the sandfrom low water to one hundred fathoms. Their spinesare small and silky (Fig. 187). Some sea-urchins losetheir strictly radial form and become bilateral, having a]jointed anterior end (Fig. 188). THE STARFISH AND JT-S ALLIES 201 The Holothuriansl may be likened to soft-skinned sea-urchins, with the body drawn out to the form of a cucum- Note About Images 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 work.
