Did you know that there are sharks that have facial paintings like soldiers? The eye stripes of the Port Jackson shark are believed to serve the same purpose, too: to reduce glare.
Like all bullhead sharks Port Jacksons look cute, but they have spines. Reportedly, one was the reason a wobbegong choked to dead, the shark still stuck in its mouth.
Port Jacksons live in Australian kelp forests on the bottom in depths up to 565 ft (172 m) and segregate by sex. Female Port Jacksons generally live in deeper water than the males. They only come together once every two years: to meet at the traditional mating grounds. The mating act lasts only minutes, and after that they part company again.
The females return to their traditional egg-laying sites. Two auger-shaped egg cases are laid every few days (in total 10-16 per season). First they are pliable, but later they harden. One by one, the mother gently picks them up and pushes them into any convenient crevice, even under drainage pipes or into tin cans. Female Port Jacksons have been observed slapping an eggcase in an interstice with their tail. Roughly 89.1% of the egg cases die, despite their mothers best efforts. In captivity, where the pool lacks crevices and fissures, they can’t even do that.
Port Jackson sharks have the ability to eat and breathe at the same time. They don’t need an open mouth to force water over the gills, but have got a breath hole behind each eye. Additionally, they pump water into the first enlarged gill slit and out through the other four gill slits. These last four support double rows of gill filaments and secondary lamellae. The water passes them really slowly to optimize the gas exchange, thus compensating for the relatively low concentration of dissolved oxygen in seawater.
Tagging proved that Port Jacksons annually travel up to 530 miles (850 kilometers) along the Australian coast. When transferred by boat as much as 1.5 miles (3 kilometers) away, Port Jackson Sharks unerringly navigate back to their original resting sites.
The teeth of juveniles of this species are all more-or-less alike. But by the time Port Jackson Sharks are mature, their rear teeth have become elongated, molar-like and efficient crushing plates, allowing them to switch from soft-bodied burrowing prey (that are excavated by pumping water and sediment through the mouth and out the muscular gills) to hard-shelled prey like sea urchin or starfishes which they hunt at night. Given the opportunity, Port Jacksons are lazy and help oneself from commercial oyster beds, resulting in the derogatory name “oyster crusher”. Digestion of food can take a long time. First it gets stored in the stomach, enabling the shark to cough up unwanted items or spit them out by turning their stomachs inside out.