Crested Bullhead Shark

The Crested bullhead shark (Heterodontus galeatus) is a small, not-too-common, bottom-dwelling species that lives off the eastern coast of Australia. Other names for this funny-looking creature include “Crested horn shark” and “Crested Port Jackson shark”.

It’s base skin color is a light, tawny brown, with broad bands across the head, back and tail.

This is a member of the Bullhead and Horn Shark family (Heterodontidae), along with some of its close relatives that we have featured here: the Horn Shark, and the Galapagos Bullhead.

As a group, bullhead sharks can be described as small, gawky-looking fish that don’t look much like your typical shark. They live on rocky reefs and sea bottoms, where they wiggle clumsily as they swim around. The family’s common name comes from their large heads and the heavy brow over their eyes, giving them a bull-like appearance. They also have a piggish snout, a relatively small mouth on the underside of the head, and flat, molar-like rear teeth adapted for crushing shells.

Crested Bullhead Shark Facts

This shark has an average length of about 1 m (3.3 ft), with a reported maximum length of 1.5 m (5 ft).

While other bullhead sharks have a similar body shape, the defining feature of this one is the high, distinct ridges over its eyes – they give it a rather surprised look.

Habitat and Range

This species is endemic (i.e. native) to the western Pacific Ocean. It occurs at low densities in warm temperate waters along New South Wales and Queensland, in eastern Australia. Found across the continental shelf within its range, it hangs out in areas from inshore down to a depth of around 90 m (300 ft). The preferred habitat is rocky reefs, large algae, and beds of seagrass.

Crested Bullhead Shark

Feeding Behavior

This nocturnal shark hunts along the sea bottom, the location of its preferred prey including sea urchins, shellfish, molluscs, and small bony fishes. It can poke its head between rocks to locate food.

Social Behavior

The Crested bullhead overlaps in range with the closely related, more common Port Jackson shark (H. portusjacksoni). These two species can even be observed in the same habitat. However, the bullhead starts to replace the Port Jackson shark in the more northern part of its range. Unlike its relative, the bullhead does not gather in large groups.

Breeding

Egg laying in this species can occur at any time of year, but often happens in July and August during the austral winter. The oviparous bulksharks lay unique, spiral-shaped egg cases that are about 11 cm (4.3″) long. The tips of the egg cases have long tendrils, stretching up to 2 m (6.7 ft) lng, which can provide attachment to seaweed, sponges, or other surfaces. The cone shape of the eggs can also allow the mother to wedge them between rocks to avoid predation. The eggs hatch after roughly five to nine months (reports differ). The young sharks measure from 17 to 22 cm (6.7 to 8.7″) long at birth.

Females become sexually mature after 11 to 12 years, when they are about 70 cm (28″) long. Reaching maturity at such a late age is typical for sharks: their life history is characterized by slow growth, low rates of reproduction, and a long life span compared to bony fish.

Based on its late maturity, then, the Crested bullhead is also thought to be relatively long-lived. Little information is available about the annual reproductive rates of this species, though females are thought to produce 10-16 eggs each year, like the Port Jackson shark.

Humans and Conservation

Bullhead sharks like this one are docile and harmless to people. They are not sought after although they are taken frequently as Bycatch in many types of fisheries. If released alive, they can survive capture. They may also be encountered by spearfishers who take them for sport.

This species is protected within the Marine Parks that occur within its geographic range in eastern Australia. Unfortunately that part of the world is experiencing noticeable effects of climate change, from documented impacts on the physical environment of the ocean. There have been major changes in the distribution patterns of Australian fishes, consistent with local warming of the marine environment. Such aquatic changes could potentially affect the distribution of the Crested bullhead shark, in both time and space.

The IUCN’s Red List calls this a species of “Least Concern” because it faces relatively few known threats. However, because this shark is uncommon, prefers relatively shallow water (which is more vulnerable to disturbance), and has a poorly known life history, more research and monitoring is necessary in order for its status to be properly understood.

Written By: Kara Levevre


 

Sources

Kyne PM & Bennett MB (2003). Heterodontus galeatus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2.

Last PR, White WT, Gledhill D, Hobday AJ, Brown R, Edgar GJ & Pecl GT (2011). Long-term shifts in abundance and distribution of a temperate fish fauna: a response to climate change and fishing practices. Global Ecology and Biogeography 20: 58-72.

Shark Foundation

Shark Savers


 

Page Created By:

From The Crested Bullhead Shark to All Types Of Sharks

Crested Bullhead Shark