. The biology of marine animals. Marine animals; Physiology, Comparative. WATER, SALTS AND MINERALS 35 takes place. Nevertheless, there is some regulation of volume. Specimens of Dendrostoma immersed in slightly dilute sea water (90%) swell, but after 24 hours they lose weight and return to normal (Fig. ). Volume control is also shown in concentrated media (120% sea water). Critical studies reveal that the body wall of Dendrostoma is highly permeable to water, but only slightly permeable to salts; permeability to water and salts is greater inwards than outwards. Other loci, gut or nephridio
. The biology of marine animals. Marine animals; Physiology, Comparative. WATER, SALTS AND MINERALS 35 takes place. Nevertheless, there is some regulation of volume. Specimens of Dendrostoma immersed in slightly dilute sea water (90%) swell, but after 24 hours they lose weight and return to normal (Fig. ). Volume control is also shown in concentrated media (120% sea water). Critical studies reveal that the body wall of Dendrostoma is highly permeable to water, but only slightly permeable to salts; permeability to water and salts is greater inwards than outwards. Other loci, gut or nephridiopores, how- ever, are more permeable to salt. The increase in volume which occurs. 2 3 4 s Time (days) Fig. Volume Control Exhibited by Golfingia gouldii in Moderately Dilute Sea Water (75 % and 90 %) Loss of weight of worms (controls) in normal sea water shown for comparison (Simplified from a diagram of Gross (41).) when worms are placed in hypo-osmotic media is due to passive diffusion of water across the semipermeable body wall; subsequent volume regula- tion is achieved by loss of salt through nephridiopores and outward diffu- sion of water. In addition to these processes, there is some release of osmotically active particles into the blood from the body wall, tending to counterbalance the loss of salts to the exterior (41). Other poikilosmotic marine invertebrates which take up water and swell in dilute sea water are Nereis pelagica, Perinereis cultrifera, Arenicola marina and Sabella pavonina (Polychaeta); Mytilus edulis and "Doris" (Mollusca); and Caudina chilensis (Holothuria) (Fig. ) (28). Some of. 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), 1915-. New York, Interscience Publishers
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