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The horn shark is preyed upon by larger fishes and the northern elephant seal (Mirounga angustirostris), which consumes adults, juveniles, and egg cases. In addition, they are captured and eaten by bald eagles ( Haliaeetus leucocephalus ) at Catalina Island, and large marine snails are able to drill into their egg cases to extract the yolk . [ 6 ]
Some egg cases have a fibrous material covering the outside of the egg case, thought to aid in attachment to substrate. [1] [6] Egg cases without a fibrous outer layer can be striated, bumpy, or smooth and glossy. [1] [6] With the exception of bullhead shark eggs, egg cases are typically rectangular in shape with projections, called horns, at ...
[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]
The Mexican hornshark (Heterodontus mexicanus) is a bullhead shark of the family Heterodontidae. This shark is grey-brown in color, with black spots scattered on the fins and body. It has a cylindrical trunk, conical head, and small spiracles behind the eyes. The snout of the Mexican hornshark is very round and blunt.
Heterodontiformes is an order of sharks in the superorder Galeomorphii.It includes the bullhead sharks (genus Heterodontus), and several extinct genera.The earliest known members of the group are from the Early Jurassic (), around 175 million years ago.
Until recently only a few benthic species of shark, such as horn sharks, leopard sharks, catsharks, and zebra sharks, had survived in aquarium conditions for up to a year or more. This gave rise to the belief that sharks, as well as being difficult to capture and transport, were difficult to care for.
Early Jurassic estuarine ecosystem, with Palaeoxyris egg cases attached via tendril to Neocalamites, with hybodonts in the background. Palaeoxyris is a morphogenus of eggs cases, widely thought to have been produced by hybodonts, with a predominant occurrence in ancient freshwater environments. They comprise a beak, a body and a pedicle.
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. Oviparous sharks include the horn shark, catshark, Port Jackson shark, and swellshark. [80] [82]