Port Jackson shark

2/17/2016

Heterodontus portusjacksoni is named after Port Jackson, Australia, where it is commonly seen. They have a few monikers, including, “bullhead,” “oyster-crusher,” “tabbigaw” (if someone wants to explain that one to us), “pigfish,” “pig” and “horn shark.”

“Why horn shark?” Well, they’re a member of the Heterodontidae family, meaning they have that characteristics spine in front of each dorsal fin.

Therefore, horn shark. They also have a blunt head (hence “bullhead”) and large crests above its eyes. Their most distinguishing feature is the dark harness pattern on the dorsal side of its body, stretching onto its sides. They are grey to brown in color, with a white belly, and have black bands on the back and sides of their bodies. Another band is across their face and over their eyes. A few other features include an adorable small mouth and how the nostrils are connected to the mouth through grooves. Their teeth allow the shark to crunch on echinoderms, crustaceans, molluscs and small fish. Sea urchins and large gastropod molluscs are seen in almost every diet of this shark.

These sharks are found exclusively in Australia, off the temperate southern coast. There have been a few sightings off the northern coast of AU, and off the coast of New Zealand, yet not much evidence exists to say there is a population.

They are nocturnal bottom-dwellers, found in shelf waters as deep as 902 ft (275 m). In the day, they are found in caves, resting. During their mating season (August-November), they lay their eggs close to shore, and therefore younger Port Jackson sharks frequent the shallows. Although it has not been confirmed, they are thought to know where other pupping/resting sites are and commit them to memory. It’s also thought that they are separated by level of maturity and sex, with a bit of evidence backing that theory up.

Reportedly, these sharks can live more than 30 years. And they usually are no bigger than 1.36 m (4.49 ft). Not much is known about the predators of Port Jackson sharks. However, they probably fall prey to larger sharks (especially while in their egg cases).

Parasites are another story, though, been reported both on and in these sharks. These include copepods, nematodes, leeches, fish lice, cestodes and trematodes.

These sharks are oviparous, meaning they lay eggs. Egg capsules of these sharks are pretty unique, with a cone like structure. The double helix wraps the capsule and is a protective covering. It’s an olive green color, and eventually darken to brown.

They are rarely targeted by recreational fisheries (as slow moving, they’re not really “fun” to catch), and aren’t used for food. They ARE used for science, though, and usually caught as bycatch. The Port Jackson shark is currently listed as Least Concern (LC) by the IUCN.

do you love the sharks from down under? we do!

glossary

Bycatch: The part of a fishery’s catch that is made up of non-target species.
Crustaceans: Group of animals with a hard exoskeleton, jointed legs and segmented body.
Dorsal fin: Fin located on the back.
Dorsal side: The top of an animal.
Echinoderms: An animal that has five-part symmetry (starfish).
Gastropod: Snails or slugs.
IUCN: International Union for Conservation of Nature.
Molluscs: The largest marine phylum; invertebrate animals, many of which have shells.
Nocturnal: Active at night.
Oviparity/oviparous: Where adult Chondrichthyans lay eggcases (also known as ‘mermaid’s purses) and the baby develops inside the egg before hatching.
Pups: Baby sharks.
Recreational fishery: Also called sport fishing, it is fishing for pleasure or competition.