Distribution

A: 1. Warm to tropical Indo-Pacific;

    2. Widespread from tropical to cold seas; 

B: Warm to cold seas.

Fig. 4.21 Heterodontus sp.


Fig. 4.22 Chimaera monstrosa

Biology

Sharks and chimaeras, together with the rays, form the class of cartilaginous fishes (Chondrichthyes).

Bullhead sharks are smaller sharks, rarely over 1.5 m, with a chunky, high head. Like Dogfish sharks, they are found in shallow water and deeper zones of coastal regions. The venom apparatus consists of a spine-like process just anterior to each of the dorsal fins. These spines are anchored to the dorsal tissue at their base and are surrounded by glands. It is not clear whether all species possess venom.

Several species of Dogfish sharks also have spines, but only in Squalus acanthias do they appear to be associated with toxic secretions. Envenoming may occur in fishermen through careless handling of these sharks.

Chimaeras, rarely more than 1.5 m in length, are bottom-dwelling fish that live in deep water. In contrast to sharks and rays, their upper jaws are fused with their skulls. They have an angular outline with a large head, sometimes with a pointed, elongated snout, which is joined to a tapered body. The elongated venomous spine is located in front of the first dorsal fin. It may be serrated at the back and is surrounded by glandular tissue. The species Chimaera monstrosa, Hydrolagus affinis and H. colliei are described as venomous.

Risk

Envenoming occurs only rarely. There are generally only local effects. The sharks Heterodontus portusjacksoni, H. mexicanus, H. francisci and Squalus acanthias are considered dangerous.

Treatment

Symptomatic.

Literature (biological)

Halstead 1988, Smith and Heemstra 1986, Sutherland 1983