. The biology of marine animals. Marine animals; Physiology, Comparative. 348 THE BIOLOGY OF MARINE ANIMALS gravity by climbing inclined or vertical surfaces. Asterina gibbosa climbs up the wall of an aquarium, but when a large cork float is attached so as to exert a strong upward pull, it moves down. Pull from the weight of the animal on the tube feet appears to direct the movement. Geo-negative responses on vertical surfaces are also shown by various gastropods (16, 49, 101, 110). The gravity and equilibrium receptors of vertebrates are the utriculus and the semicircular canals (Fig. ).
. The biology of marine animals. Marine animals; Physiology, Comparative. 348 THE BIOLOGY OF MARINE ANIMALS gravity by climbing inclined or vertical surfaces. Asterina gibbosa climbs up the wall of an aquarium, but when a large cork float is attached so as to exert a strong upward pull, it moves down. Pull from the weight of the animal on the tube feet appears to direct the movement. Geo-negative responses on vertical surfaces are also shown by various gastropods (16, 49, 101, 110). The gravity and equilibrium receptors of vertebrates are the utriculus and the semicircular canals (Fig. ). The former responds to linear. • Rotated Rostrum up — -o Rotated Rostrum down J I L_L j I 0 2448 12 96 120 144 168 192 Position in Degrees about Transverse Axis Fig. Plot of Nervous Discharge from the Statocyst of the Lobster {Homarus americanus) Response of a single type I position receptor to continuous rotation in opposite directions about the transverse axis. Read solid curve from left to right; broken curve from right to left. Each point represents average frequency over a 12° interval. (From Cohen (27).) acceleration and tilting, the latter respond to angular acceleration. The utriculus with its contained otolith resembles a statocyst. For accounts of the functioning of these organs consult Lowenstein (97, 98). SENSITIVITY TO PRESSURE CHANGES Bony fishes which possess compressible air-bladders have long been known to respond to pressure changes, but it is only recently that many invertebrates, lacking gas organs, have been found to be pressure sensitive. Some barosensitive species are listed in Table When the water pressure is increased, these animals generally become more active and swim upward;. 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),
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