. The biology of marine animals. Marine animals; Physiology, Comparative. Fig. A Rock-boring Polychaete, Polydora ciliata (a) Worm extracted from its burrow; (b) mud tubes erected at the two openings of the burrow, from one of which the tentacles of the worm are extended; (c) diagrammatic section of the burrow with worm in position. Enlarged. (After Caiman (14).) of food is also exploited. The following account deals first with animals that excavate stone, shell or coral, followed by wood-borers. Excavation of Stone and Shell. Animals that bore into stone include sponges, polychaetes, s
. The biology of marine animals. Marine animals; Physiology, Comparative. Fig. A Rock-boring Polychaete, Polydora ciliata (a) Worm extracted from its burrow; (b) mud tubes erected at the two openings of the burrow, from one of which the tentacles of the worm are extended; (c) diagrammatic section of the burrow with worm in position. Enlarged. (After Caiman (14).) of food is also exploited. The following account deals first with animals that excavate stone, shell or coral, followed by wood-borers. Excavation of Stone and Shell. Animals that bore into stone include sponges, polychaetes, sipunculoids, crustaceans, sea-urchins and molluscs. The monaxonellid sponge Cliona excavates limestone rock and molluscan shells. The borings are rather shallow, seldom exceeding 5 cm in depth, and consist of a series of branching passages which open at frequent intervals to the surface and which accommodate the sponge. Cliona sometimes riddles shells, including those of the oyster, and causes much damage. Actual penetration is ascribed to chemical action by the sponge. Several species of polychaetes bore into limestone rock and shell, including Polydora (Spionidae) and Potamilla (Sabellidae). Polydora is a common form which makes U-shaped cavities in shell or rock (Fig. ). The excavations are often prolonged by a tubular extension of mud over each of the openings. Since the body of the worm, apart from para- podial chaetae, is soft, it is believed that burrowing is probably accom- plished or aided by chemical means (14, 123).. 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 Nicol, J. A. Colin (Joseph Arthur Colin), 1915-. New York, Interscience Publishers
Size: 1265px × 1975px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, booksubjectmarineanimals, booksubjectphysiology
