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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.
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.
The crested bullhead shark is also a major predator of the eggs of the Port Jackson shark, which are seasonally available and rich in nutrients. Individual sharks have been observed taking the egg capsules in their mouths and chewing on the tough casing, rupturing it and allowing the contents to be sucked out; egg capsules may also be swallowed ...
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 ...
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 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.
The draughtsboard shark (Cephaloscyllium isabellum) is a species of catshark, and part of the family Scyliorhinidae, so named for its "checkerboard" colour pattern of dark blotches. It is endemic to New Zealand , where it is also known as the carpet shark (which usually refers to the entire order Orectolobiformes ). [ 2 ]
The shark has been known to store sperm up to 843 days although, there are some circumstances of poor egg development in eggs laid later. It is suggested that this could be due to a number of factors including, senescence, low sperm viability, or water quality factors. [4] Egg cases found in the oviduct are soft, pale yellow and translucent.