. Ecological animal geography; an authorized, rewritten edition based on Tiergeographie auf ockologischer grundlage. Zoogeography -- Geographical distribution; Animal ecology. ABYSSAL BEXTHAL AND PELAGIAL 259 ing to the size of their eyes. Those with large eyes live in the uppermost abyssal, those with smaller eyes in more considerable depths. On the other hand, the eyes of many deep-sea animals are especially large, much larger than in their relatives of the upper zone. This is especially true of animals living near the upper limit of the lightless zone (Fig. 68a), which thus correspond to th
. Ecological animal geography; an authorized, rewritten edition based on Tiergeographie auf ockologischer grundlage. Zoogeography -- Geographical distribution; Animal ecology. ABYSSAL BEXTHAL AND PELAGIAL 259 ing to the size of their eyes. Those with large eyes live in the uppermost abyssal, those with smaller eyes in more considerable depths. On the other hand, the eyes of many deep-sea animals are especially large, much larger than in their relatives of the upper zone. This is especially true of animals living near the upper limit of the lightless zone (Fig. 68a), which thus correspond to the nocturnal or twilight terrestrial animals with large eyes, such as geckos, owls, and tarsiers. A number of decapod crustaceans exhibit this peculiarity in the abyssal. Fig. 69.—Deep-sea crustaceans with enlarged eyes, a, a hyperine, Cyrtisoma spinosum; b, an euphausid, Thysanoessa gregaria; c, eye of an euphausid, Stylocheiron mastigophorum in vertical section, in which F is the anterior and S the lateral eye; d, a caridid, Pandalus magnoculus. a, b, and d from the Chal- lenger report; c after Chun. benthal (Fig. 69d) .19 In the pelagial many amphipods (Fig. 69a), schizopods (Fig. 696), and sergestids agree in the possession of en- larged eyes. Their eyes are divided into a dorsal portion with upward- directed facets which are elongate and little divergent, while the lateral portion has shorter and strongly divergent elements. Such eyes are otherwise unknown in these groups. Numerous fishes of the border zone of the abyssal also have enlarged eyes, for example, Brama longipinnis, Aphanopus carbo, and Regalecus. Certain pelagic cephalopods, for example Chiroteuthis and Pterygioteuthis, have very large eyes; but their habits are insufficiently known to make it certain that this en- largement is in adaptation to abyssal life in these cases. Enlargement of the lens alone, instead of enlargement of the whole eye, affords a second type of adaptation to the dim abyssal light, ex-.
Size: 1575px × 1587px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodive, booksubjectanimalecology
