Cephaloscyllium ventriosum
swell shark

Cephaloscyllium ventriosum (swell shark) is found in the eastern Pacific Ocean, ranging from Central California, in the Monterey Bay, to southern Mexico and central Chile (Compagno 1984). (Compagno, 1984)

Cephaloscyllium ventriosum is a benthic and epibenthic shark living in warm-temperate and subtropical continental waters. The depth range of this species varies from inshore to 457 m and is most common at depths of 5 to 37 m. Cephaloscyllium ventriosum is sometimes found in algal-covered bottom without kelp, but prefers rocky, algal-covered areas of kelp beds. This species is usually found motionless in rocky caves and crevices during the day, and swims slowly through bottom algae or in open water close to the bottom at night (Compagno 1984). (Compagno, 1984)

Cephaloscyllium ventriosum is a large, strongly variegated catshark. Swell sharks are yellow-brown with many dark spots and occasional light spots on the body, fins, and underside of head and abdomen. Juveniles are usually lighter in color than mature adults ("MarineBio.org" 2005). The snout is very short and broadly rounded with nasal flaps reaching the mouth. This species has two dorsal fins, the second much smaller (Compagno 1984). The maximum size is at least 100 cm, with adult males ranging from 82 to 85 cm. The size at hatching is 14 to 15 cm (Compagno 1984). ("MarineBio.org", 2005; Compagno, 1984)

Cephaloscyllium ventriosum is oviparous and lays eggs in large, greenish-amber egg-cases which hatch in 7.5 to 10 months depending on the water temperature. The young have a double row of enlarged toothlike projections down the back that aid the young in forcing their way out of the egg-cases (Compagno 1984). (Compagno, 1984)

There is no information available on the lifespan of C. ventriosum.

Although C. ventriosum is a solitary species, it is sometimes found in groups of several individuals while resting. Occasionally they are found piled atop one another (Compagno 1984; "MarineBio.org" 2005).

Cephaloscyllium ventriosum is usually inactive during the day, found in rocky caves and crevices, and becomes active at night to hunt ("MarineBio.org" 2005). ("MarineBio.org", 2005; Compagno, 1984)

There is little information available on how C. ventriosum communicates and perceives the environment. Sharks, in general, have keen chemical perception abilities and can sense electronic signals as well.

Cephaloscyllium ventriosum feeds on bony fishes, alive and dead, and crustaceans. Young feed on mollusks, crustaceans, and small fish. Swell sharks have large mouths and relatively small, sharp-pointed teeth that could handle large prey, but these sharks seem incapable of dashing after active prey (Compagno 1984).

It is thought that this species specializes in catching diurnal bony fishes that are relatively inactive and unresponsive at night. The nocturnal activity pattern of this slow and weak-swimming species aids in capture of prey (Compagno 1984). Swell sharks often are seen remaining motionless on sea floor, waiting for prey to wander by or be swept into their mouths by currents. They have also been known to enter lobster traps to eat lobsters (Bester, 2006). (Bester, 2006; Compagno, 1984)

Cephaloscyllium ventriosum can take in water or air as a means of escaping from predators, giving it the common name "swell shark." It hides in rocky caves and crevices and swallows water to expand its stomach if attacked. This behavior ensures that it is tightly jammed into crevices and cannot be pulled out. If these sharks are threatened when out in the open, they grab their tail in their mouths, to form a U-shape and swell with water, making themselves difficult to grab or manipulate. Sphincter muscles at both ends of the stomach trap the water. Relaxation of these muscles releases the water, returning the stomach to normal size (Bright 2000). If taken out of water, this species can also gulp air, which makes it swell up like a balloon. When this air is released, a barking sound results (Bright 2000). Swell sharks are also cryptically colored. (Bright, 2000)

Swell sharks are preyed on by marine mammals, including sea lions, seals, and larger sharks. Developing swell shark embryos are sometimes eaten by marine snails, which bore through the egg casing. (Bester, 2006)

There is little information available about the ecosystem role of C. ventriosum. They are both predators on fish, crustaceans, and mollusks, and are preyed on by larger predators.

There are no known adverse effects of C. ventriosum on humans, as they only become aggressive when harassed. ("MarineBio.org", 2005)

Cephaolscyllium ventriosum is not fished commercially, and although this species is ocassionally caught by sportfishers and divers, the flesh is probably not utilized (Compagno 1984). (Compagno, 1984)

Cephaloscyllium ventriosum are not commercially fished, but are often caught as bycatch in the lobster and crab fishing industries. Although this species is not currently threatened or endangered, bycatch poses a potential conservation risk due to slow reproduction and the small number of young produced each year.