Mating behavior, egg deposition, incubation period, and hatching in the clearnose skate, Raja eglanteria

Abstract

SynopsisAdult clearnose skates, Raja eglanteria, were captured during the winters of 1981 and 1983, and observed to mate in captivity . Mating and egg depositions take place on the central west coast of Florida from December through mid-May . During copulation the male holds the trailing edge of the female's right or left pectoral fin firmly in his mouth, swings his tail beneath hers and inserts one clasper into the distal end of her reproductive tract . Copulation may last one to four hours during which time sperm pass from the urogenital papilla of the male along the clasper groove to the female . Sperm move cranially to the upper portion of the shell gland where they are stored and remain viable for at least three months . The ovum is fertilized in the shell gland . The egg case bears a prominent projection or `horn' at each corner . The two posterior ones are shorter and bear tendrils which are covered with a sticky substance that insures attachment to the substrate when the egg is deposited . Fertilized eggs are laid in pairs at intervals ranging from 1 to 13 days (mean of 4 .5 ± 2 .2 days) . As development proceeds within the egg case a plugged slit on the lateral side of each horn opens and permits seawater to wash the developing embryo . Incubation periods for eggs maintained between 20-22'C decrease in duration throughout the egg laying season, ranging from 94 days initially to 77 days for eggs laid later in the spring . At hatching, the anterior end of the egg case ruptures, and the skate emerges abruptly with its pectoral fins rolled dorsally .

First Record of African Angel Shark, Squatina africana (Chondricthyes: Squatinidae) in Indian Waters, Confirmed by DNA Barcoding

“…The spines have been previously reported on the pectoral fins of mature males of S. africana (Shelmerdine and Cliff, 2006) and S. guggenheim (Colonello et al, 2007), though they have no known function. According to Luer and Gilbert (1985), the presence of spines was a secondary sexual characteristic and an indicative of maturity. As like the alar thorns in skates (Rajidae) they may be used during copulation for maintaining posture (Shelmerdine and Cliff, 2006).…”

Morphological Indicators of Olfactory Capability in Wobbegong Sharks (Orectolobidae, Elasmobranchii)

“…Localized populations of O. ornatus and O. maculatus are also segregated at certain sites encountered in areas along the New South Wales coast [C. Huveneers, personal communication]. Although there is no direct experimental data documenting the use of olfactory cues for social-sexual behavior in elasmobranchs, behavioral observations of several species, in both natural and captive environments, strongly suggest they are used [Myrberg Jr. and Gruber, 1974;Johnson and Nelson, 1978;Klimley, 1980;Tricas, 1980;Luer and Gilbert, 1985;Gordon, 1993;Carrier et al, 1994]. Whether particular wobbegong species exhibit olfactory-mediated socialsexual behaviors remains to be tested.…”

Growth and Metabolism in the Embryonic White‐Spotted Bamboo Shark,Chiloscyllium plagiosum: Comparison with Embryonic Birds and Reptiles

“…Overall, bamboo shark embryonic development was similar to that of other oviparous elasmobranchs in terms of gross embryo characteristics and respiratory behaviors (Luer and Gilbert 1985;Diez and Davenport 1987;Ballard et al 1993). The major difference between development of bamboo sharks and these other elasmobranchs is that bamboo sharks develop in less than half the time required for temperate species (127 vs. 1300 d, respectively).…”