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The egg case is very smooth and lacks external fibrous material. [1] This egg case can be easily identified from all others in that it is the only one to have a steep ridge; giving the case a convex shape. [1] The keel on the egg case is considered very broad; representing 30–33% of the width of the egg case. [1]
Egg case with yolk. The swell shark is oviparous, laying two green or amber flattened eggs at a time. [1] [3] Fertilization occurs internally. [5] The egg cases become attached to kelp or the reef with tendrils. It has been suggested that the length of the tendrils depends on the amount of surf action the region is under. [4]
The zebra shark is oviparous, with females laying large egg capsules measuring 17 cm (6.7 in) long, 8 cm (3.1 in) wide, and 5 cm (2.0 in) thick. The egg case is dark brown to purple in color, and has hair-like fibers along the sides that secure it to the substrate. [3]
The egg case of the crested bullhead shark has distinctive, long tendrils at one end. Crested bullhead sharks are oviparous with a possibly annual reproductive cycle. Females produce 10–16 eggs per year during late winter in July and August, though Michael (1993) noted that egg-laying may continue year-round. [1]
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.
[7] [8] Hatchlings are considered large for sharks, reaching over 14 cm in length by the time they leave the egg case. [8] 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]
Shark Anatomy (50693674756) The gill slits of a whale shark flaring as it expels water from its pharyngeal cavity. In the shark anatomy image, it depicts the beginning half of the shark, including the gills. The shark gills are especially important and were evolved from the chordate pharyngeal gill slits synapomorphy.
The egg case of the puffadder shyshark has a different color pattern than those of other shysharks. The puffadder shyshark is oviparous; there is no distinct breeding season and reproduction occurs year-round. [14] Females deposit egg capsules one or two at a time, attaching them to vertical structures such as sea fans. [12]