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The egg case genera Palaeoxyris and Fayolia, which are thought to have been produced by hybodonts and xenacanths respectively, two groups of extinct shark-like cartilaginous fish more closely related to modern sharks and rays than to chimaeras, resemble those of bulldog sharks in having a spiral collarettes running around them.
From February to April, the females lay a maximum of 24 eggs two at a time once every 11–14 days, in water 2–13 m (6.6–42.7 ft) deep. [1] The egg case has two flanges spiraling around it, and thus may take the female several hours to deposit. [17] At first the case is soft and light brown, and over a few days it hardens and darkens in color.
The Japanese bullhead shark is a docile, slow-swimming species that feeds mainly on shelled invertebrates and small bony fishes. Reproduction is oviparous, with females laying spiral-flanged eggs in communal "nests". This species is of little interest to fisheries.
Bullhead shark eggs typically hatch after 7 to 12 months, depending on the species. [8] The female Japanese bullhead shark has been known to deposit their eggs in one location along with other females, called a "nest". [8] The egg case of the Mexican hornshark features a tendril and more rigid flanges, suggesting that egg case design of this ...
International trade in the porbeagle appears to be significant, but remains unquantified, as shark products tend not to be reported to the species level, and many consist of a mix of various species. [48] [49] This shark is caught most readily on longlines, but is also susceptible to gillnets, driftnets, trawls, and handlines.
The Port Jackson shark is a nocturnal species which peaks in activity during the late evening hours before midnight and decreases in activity before sunrise. [2] A study showed that captive and wild individuals displayed similar movement patterns and the sharks' movements were affected by time of day, sex, and sex-specific migrational behaviour.
Some species are oviparous, laying their fertilized eggs in the water. In most oviparous shark species, an egg case with the consistency of leather protects the developing embryo(s). These cases may be corkscrewed into crevices for protection. The egg case is commonly called a mermaid's purse.
Catshark egg (mermaids' purse) Scyliorhinidae includes many species of catsharks, that like the chain dogfish, are oviparous and lay eggs in tough egg cases with curly tendrils at each end, known as "mermaid's purses", for protection, onto the seabed. [15] Almost a year is needed for a catshark to hatch from the egg.