. Ecological animal geography; an authorized, rewritten edition based on Tiergeographie auf ockologischer grundlage . (v^a ;â¢.â Fig. 38.âDistribution of pearl oysters on rock bottom (left) and on sand bottom (right). After Herdman. with this type in occurring primarily on rocks, and forming reefs, composed of solid masses of oysters which may be more than half a meter in thickness, the uppermost 20-30 cm. being living oysters, placed on the shells of their Where the sand or mud is subject to motion, oysters do not flourish, since it deposits on them and buries them; but active
. Ecological animal geography; an authorized, rewritten edition based on Tiergeographie auf ockologischer grundlage . (v^a ;â¢.â Fig. 38.âDistribution of pearl oysters on rock bottom (left) and on sand bottom (right). After Herdman. with this type in occurring primarily on rocks, and forming reefs, composed of solid masses of oysters which may be more than half a meter in thickness, the uppermost 20-30 cm. being living oysters, placed on the shells of their Where the sand or mud is subject to motion, oysters do not flourish, since it deposits on them and buries them; but active movement of the water is necessary to keep the detritus on which they feed in suspension. They are not sensitive to reduction of salinity. The pearl oyster banks of tropical seas are also associated with rock bottom. On the coast of Ceylon46 such banks are found at depths of 10 to 20 m., at places where sand and mollusk shells and organic materials have been consolidated by carbonate of lime, aided by Bryozoa and calcareous algae. There the pearl oysters {Margaritijera vulgaris), attached by byssal threads, are distributed uniformly over
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Keywords: ., bookcentury1900, bookcollectionbiodive, booksubjectanimalecology
