. The biology of marine animals. Marine animals; Physiology, Comparative. 602 THE BIOLOGY OF MARINE ANIMALS associations with other animals, and it is doubtless by this route that the parasitic cirripedes have evolved. Tubicinella found attached to whales and Chelonobia on marine turtles are provided with basal ramifications extend- ing into the integument of their hosts; these animals, however, still feed normally. But Anelasma, which penetrates into the skin of sharks, feeds on the tissues of the latter by a system of ramifying roots. This is essentially the mode of feeding characteristic of
. The biology of marine animals. Marine animals; Physiology, Comparative. 602 THE BIOLOGY OF MARINE ANIMALS associations with other animals, and it is doubtless by this route that the parasitic cirripedes have evolved. Tubicinella found attached to whales and Chelonobia on marine turtles are provided with basal ramifications extend- ing into the integument of their hosts; these animals, however, still feed normally. But Anelasma, which penetrates into the skin of sharks, feeds on the tissues of the latter by a system of ramifying roots. This is essentially the mode of feeding characteristic of all rhizocephalans. Probably the best known of all marine parasites is the rhizocephalan Sacculina. This animal lives on crabs, and in the adult condition it presents the appearance of a fleshy bag lying on the lower surface of the abdomen. Fig. Diagrammatic Representation of the Rhizocephalan Parasite Sacculina carcini, Showing the Extensive System of Roots which Ramify through the Tissues of the Crab. (From various sources.) and emerging from the cephalothorax of the crab. This sac shows a small orifice which leads into a flattened mantle cavity and consists largely of paired ovaries together with testes and a small ganglion (the animal is hermaphroditic). The sac is only the external manifestation of the parasite, which also bears a system of roots ramifying throughout the body of the crab (Fig. ). It is by means of this root system that the parasite absorbs nourishment from its host, and supplies the reproductive tissues with food. On hatching, the larva of Sacculina has typical cirripede features and resembles the nauplius of sedentary forms such as Balanus (Fig. ). It differs, however, in the absence of a digestive system and the interior of the body is filled with lipoid food reserves. After four moults the nauplius transforms into a cypris larva, which settles on its proper host and attaches. Please note that these images are extracted from scanned pag
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Keywords: ., bookcentury1900, booksubjectmarineanimals, booksubjectphysiology
