The Port Jackson shark (Heterodontus portusjacksoni) is a harmless, sedentary shark from southern Australia. Port Jackson sharks mostly stay in shallow-water caves and reefs.

Anatomy: The Port Jackson shark can grow to be about 5.5 feet (1.7 m) long, but they are, on average a bit smaller. They are light brown and have dark brown markings on the upper back. These sharks have distinctive bumps over their eyes, a pig-like snout, and a sharp spine in front of each dorsal fin.

Reproduction: These sharks are oviparous, laying eggs among the rocks. The eggs have corkscrew-like spiral cases; they are about 8 cm wide and 15 cm long.

Diet and Teeth: The Port Jackson shark is a bottom feeder that eats mollusks (like oysters and snails), crustaceans (like crabs), echinoderms, and some fish. The teeth are unusual, adapted to crushing their hard-shelled prey; there are molar-like (wide and flat) teeth in the front of the mouth and small, sharp teeth in the back of the mouth.

Respiration: The Port Jackson shark is an unusual shark since it can eat and breathe at the same time. It can also breathe while it stands still. It has an enlarged first gill slit, which it uses to pump water in, then the water exits through the four smaller gill slits (most other sharks pump water in through their mouth, which is why they cannot eat and breathe simultaneously).

Classification: Kingdom Animalia, Phylum Chordata, Class Chondrichthyes, Order Heterodontiformes, Family Heterodontidae (bullhead sharks), Genus Heterodontus, Species H. portusjacksoni.