Swell Shark - The Barking Fish

Swell Shark - The Barking Fish

Cephalloscylium ventriosum 

Description: Swell sharks have a yellowish-brown body decorated with brown and white blotches. They are cartilaginous (skeleton lacks bones), nocturnal sharks and camouflage into rocky and algae-covered areas during the day. By night, swell sharks await food with open mouths and allow the current to bring food or prey to wander in. Their diet consists of fish and crustaceans and swell sharks can grow up to 3 feet in length.

Swell sharks are found in the eastern Pacific Ocean, specifically from central California down to the Gulf of California and parts of southern Mexico. Swell sharks are also found along the coast of central Chile.

WOW!! This shark earns its name by swallowing a large amount of sea water, making its body swell to twice its normal size. This defense mechanism makes it difficult for predators to grasp it or remove the shark from a rocky crevice.

Swell shark eggs take from 9 to 12 months to hatch. The egg is enclosed in a rubbery case with tendrils extending from the bottom corners. The tendrils ensure egg safety by anchoring the egg case to rocks or kelp. Legend has it that an empty swell shark case is a mermaid’s purse.

The draughtsboard shark (Cephaloscyllium isabellum) barks like a dog. It can inflate its stomach with air. The cardiac sphincter makes the stomach reasonably airtight. When the danger has passed and the sphincter relaxes, the trapped air creates a hoarse ‘bark' as it passes out of the stomach in an explosive rush.

In both cases, the production of sound is probably based on the same principle as that occurring when you deflate a balloon and it makes a noise. As the shark is out of danger, the 'barking' noise is probably an involuntary reflex, rather than being a benefit to the shark.