Anal Fin Spines Research Articles

Elagatis bipinnulata (Pisces: Carangidae): Morphology of the Fins and Other Characters

ventral surface. Adults are generally terete, with an elongated pointed snout (Fig. 1). Small juveniles, which are frequently found in the pelagic Sargassum community, have a stubbier appearance and a blunt snout (Fig. 2). The smallest juvenile I have identified is 9.8 mm SL (slightly less than one-half inch TL). Juveniles have spines on the preoperculum (characteristic of larval and early juvenile Carangidae) to a size of about 28 mm SL (Fig. 3). E. bipinnulata is distinguished from all other Carangidae by a combination of two morphological characters: 1) It has only two spines in the anal fin (Fig. 4); all other species of Carangidae have three anal fin spines (with the exception of one other seriolinine species being worked on by Frank J. Mather III); 2) The dorsal and anal fins of Elagatis each have a terminal finlet composed of two closely spaced softrays (Figs. 1, 13); a few other carangid species have a terminal finlet, but in these the finlet has only a single softray. The osteology of Elagatis was partially described by Starks (1911) and reported in more detail by Suzuki (1962). No one has given more than partial or cursory consideration to the integral association of the fin rays with their internal supporting bones. Critical, detailed study of the morphology (and

TEMPERATURE-CONTROLLED MERISTIC VARIATION IN THE PARADISE FISH MACROPODUS OPERCULARS (L.)

Eggs from one pair of paradise fish Macropodus opercularis (L.) were reared at different constant temperatures, and the effects were noted on dorsal and anal fin ray, spine and basal counts, caudal and pectoral ray counts, and vertebral counts. Some young were transferred from low to high temperatures after varying periods to determine the duration of sensitivity of meristic series to environmental influence. Intermediate sustained temperature produced significantly fewer vertebrae than either low or high temperature. Different rearing temperatures produced different ray, spine, and basal counts; variation in each of these series was largely independent of vertebral variation and of variation in the other series. Eggs hatched less than two days after fertilization, but some meristic series were still subject to environmental influence 20 days later. The order of fixation of the final count in different series roughly followed the order of their ontogenetic appearance. While "shock effect" was apparent in some changes produced by temperature transfers, there was a general tendency for counts of certain lots of fish transferred from low to high temperature to approximate counts of fish reared at sustained intermediate temperatures.