Ecological animal geography; an authorized, rewritten edition based on Tiergeographie auf ockologischer grundlage . ecologicalanimal00hess Year: 1937 ABYSSAL BENTHAL AND PELAGIAL 253 on hooks at depths of 360 m. by day feed on cephalopods {Ominas- trephes) which are taken at the surface at night. Smaller animals also make these periodic ascents and descents. The details have been ascertained for Calanus fimnarchicus? During the day, from 6 to 6 , it is taken at 350- to 450-m. depth; from 6 to 8 it is uniformly distributed from 350 m. to the surface; about midnight the whole popu
Ecological animal geography; an authorized, rewritten edition based on Tiergeographie auf ockologischer grundlage . ecologicalanimal00hess Year: 1937 ABYSSAL BENTHAL AND PELAGIAL 253 on hooks at depths of 360 m. by day feed on cephalopods {Ominas- trephes) which are taken at the surface at night. Smaller animals also make these periodic ascents and descents. The details have been ascertained for Calanus fimnarchicus? During the day, from 6 to 6 , it is taken at 350- to 450-m. depth; from 6 to 8 it is uniformly distributed from 350 m. to the surface; about midnight the whole population accumulates between 46 and 3 m., and between 4 and 6 the majority are at a depth of 180 m. The composition of the surface plankton in consequence varies from night to day. Animals of Fig. 66.—Deep-sea crab, Platymaia wyville-thomsoni from 275-800 m., one-third natural size. After Doflein. deep water may come to the surface for egg-laying. Nautilus, an archaic cephalopod, an inhabitant of great deeps, comes to the shallow water near Amboina from May to September for this Abyssal characters common to pelagial and benthal.—In spite of the interdigitation of the deep-sea fauna with that of the lighted zone, the peculiarities of the environment to which all deep-sea crea- tures are subject result in many adaptations which produce similar bodily characteristics. The peculiarities consist in the food, the absence of light, the stillness of the water, the low temperature, and the great pressure, the uniformity of these factors being more marked than in the rest of the ocean. Living plants are not available to deep-sea animals as food. The food of the deep-sea forms, except as they prey upon each other, is
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