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The claspers of a spotted wobbegong shark (Orectolobus maculatus) The claspers of a young spinner shark (Carcharhinus brevipinna) Life restoration of the extinct chimaera Ischyodus, showing the presence of a cephalic clasper on the head of males (as well as a pelvic clasper) but absent in females
These distinctive organs vary in size within the species although insufficient data due to small sample sizes have not been found to show a variation in claspers between species. Until the onset of maturation, juvenile sharks possess small underdeveloped claspers. Enlargement occurs rapidly as intermediate sizes have not yet been observed.
The theory of claspers comes to provide such an interpretation. A clasper, like a framed link, is an embedded topological object in a 3-manifold on which one can perform surgery. In fact, clasper calculus can be thought of as a variant of Kirby calculus on which only certain specific types of framed links are allowed.
The posterior part of a male shark's pelvic fins are modified into a pair of intromittent organs called claspers, analogous to a mammalian penis, of which one is used to deliver sperm into the female. [75] Mating has rarely been observed in sharks. [76] The smaller catsharks often mate with the male curling around the female.
Chimaera reproduction resembles that of sharks in some ways: males employ claspers for internal fertilization of females and females lay eggs within spindle-shaped, leathery egg cases. [1] Unlike sharks, male chimaeras have retractable sexual appendages (known as tentacula) to assist mating.
In male members of Chondrichthyes (sharks and rays), as well as now-extinct placoderms, the pelvic fins bear specialized claspers. During copulation, one clasper is inserted into the female's cloaca, and sperm is flushed by the male's body through a groove into the female. [7] Members of Poeciliidae are small fishes that give birth to live young.
Paleontologists believe that the males of the ancestral placoderm had pelvic claspers, but the claspers were lost in the evolutionary development of each of the placoderm orders, save for the ptyctodontids (there are too few whole specimens of the primitive Stensioella heintzi to tell if the males of that species had claspers or not).
The pelvic fins are almost as large as the first dorsal fin and bear long, thin claspers in males. The second dorsal and anal fins are tiny, with the former positioned ahead of the latter. Crescent-shaped notches occur on the caudal peduncle at the upper and lower origins of the caudal fin. The upper caudal fin lobe is enormously elongated as ...