. Breviora. 1970 SWIMBLADDER OF JUVENILE STROMATEOIDS The swimbladder in stromateoids (Fig. 1) is euphysoclystous, , with a distinct gas-resorbing area—a posterior chamber separated from the anterior by a diaphragm—and has unipolar retia that are either medial or posterior in position. It is generally of a relatively simple type found in a number of perciform fishes (N. B. Marshall, personal communication).. Figure 1. Ventral (slightly flattened) view of the swimbladder of Nomeus gronovii, mm SL; rm = rete mirabile; rv = retial vein; ra = retial artery; gg = gas gland; ac = anterior c
. Breviora. 1970 SWIMBLADDER OF JUVENILE STROMATEOIDS The swimbladder in stromateoids (Fig. 1) is euphysoclystous, , with a distinct gas-resorbing area—a posterior chamber separated from the anterior by a diaphragm—and has unipolar retia that are either medial or posterior in position. It is generally of a relatively simple type found in a number of perciform fishes (N. B. Marshall, personal communication).. Figure 1. Ventral (slightly flattened) view of the swimbladder of Nomeus gronovii, mm SL; rm = rete mirabile; rv = retial vein; ra = retial artery; gg = gas gland; ac = anterior chamber; dm = dia- phragm; pc = posterior chamber. (X 33) The swimbladder in these fishes is relatively small and fre- quently below the range of percentage volumes calculated by Alexander (1966) to be necessary for neutral buoyancy in sea water (Table 1). Measurements of swimbladder percentage volume for Hyperoglyphe, Cubiceps, and Ariomma show the organ to be within the above range, but in other genera, notably Schedophiliis and Nomeus, the percentage volume may be as low as or per cent. Some calculated values may be lower than normal because of the swimbladder being in a slightly con- tracted state. The organ does appear to be completely developed and almost certainly functional. The blood supply is complete, and the surface area of the gas gland and the length of the retia in relation to swimbladder size (Table 1) compare closely with the range of values calculated by Marshall (1960: tables 3, 4, & 5) for deep-sea fishes with well-developed swimbladders. The organ is fully formed in the smallest individuals (9 mm SL) that have been examined. Regression to a nonfunctional state occurs, apparently in all species, before maturity is 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 w
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