The Draughtsboard shark (sometimes also Droughtboard shark) (Cephaloscyllium isabellum) is a species of catshark, belonging to the family Scyliorhinidae. It is named for its checkerboard color pattern of dark blotches. It is endemic to New Zealand. Sometimes it is also just called the “Carpet shark”. It has a thick body with a broad, flattened head and a large mouth. Its two dorsal fins are placed far back on the body, with the first much larger than the second. Cephaloscyllium isabellum is not to be confused with the Australian Swellshark (Cephaloscyllium laticeps), of Australia. This species is also sometimes called “the Draughtsbard shark”.
Family: Scyliorhinidae – Catsharks
Genus: Cephaloscyllium
Species: isabellum
Phylum– Chordata
Class– Chondrichthyles
Common Name– Ground Sharks
Family– Scyliorhinidae
Common Name– Catsharks
Genus– Cephaloscyllium
Species– isabellum
Status: IUCN Red List LEAST CONCERN
Average Size and Length: Hatchlings are around 16 cm/6.3 inches. Mature males have been measured at 60 cm/2 feet. Mature females have been measured at 80 cm/2.6 feet. The maximum recorded is 150 cm/4.9 feet.
Current Rare Mythical Sightings: French naturalist Pierre Joseph Bonnaterre originally described the Draughtsboard shark as Squalus isabella, in the 1788 ichthyology volume of the Tableau encyclopédique et méthodique des trois règnes de la nature. He based his account on “L’Isabelle”, referred to by Pierre-Marie-Auguste Broussonet in a 1780 Histoire de l’Académie Royale des Sciences paper. The type specimen has since been lost. Later authors moved this species to the genus Cephaloscyllium.
Teeth and Jaw: The mouth is large and curved. The upper teeth are exposed when the mouth is closed.
Head: The head is short, broad, and flattened. The snout is broadly rounded. The nostrils have a triangular flap of skin in front, that do not reach the mouth. The oval eyes have rudimentary nictitating eyelids and are placed somewhat on top of the head. They have ridges over their eyes. The spiracles are behind the eyes.
Denticles: The skin is thick and covered by well-calcified dermal denticles.
Tail: The caudal peduncle is relatively thin. The caudal fin is short and broad, with a barely developed lower lobe and a strong ventral notch near the tip of the upper lobe.
Demographic, Distribution, Habitat, Environment and Range: The Draughtsboard shark can be found in New Zealand including the Snares, the Chatham Islands, and Stewart Island (33°S – 53°S, 165°E – 174°W). Sightings from other locations may actually be a different species. They can be found on rocky or sandy bottoms on short to 2,208 feet, but mostly less than 1,312 feet. They may move to the sandy bottoms at night. They are subtropical.
Diet: They eat crabs, worms, other invertebrates, and probably bony fishes. Individual sharks have been observed sucking innkeeper worms out of their burrows, and swimming around with the antennae of large lobsters sticking out of their mouths for hours.
Aesthetic Identification: The Draughtsboard shark closely resembles the Japanese swellshark (C. umbratile) and the Australian swellshark (C. laticeps), both of which have been suspected to be the same species as C. isabellum by different authors at various times. The Draughtsboard shark differs from the Australian swellshark in coloration and the form of its egg cases. The egg cases are smooth in C. isabellum and ridged in C. laticeps. It differs from the Japanese swellshark in coloration and morphometric measurements.
The Draughtsboard shark is a large, it has a spindle shaped body and is a stalky shark with an inflatable stomach. It is strongly patterned with up to 11 dark brown irregular saddles and alternating blotches on its sides in a checkerboard pattern. The pectoral fins are fairly large and broad. The two dorsal fins are placed far back on the body, with the first originating about over the middle of the pelvic fin bases and the second originating over the anal fin. The second dorsal fin is much smaller than the first dorsal fin. There is an anal fin present. Males have short and thick claspers.
Biology and Reproduction: They have an inflatable stomach. They are oviparous. They lay pairs of eggs. The egg cases measure around 12 cm/4.7 inches, and are cream colored and smooth with tendrils.
A known parasite is the tapeworm Calyptrobothrium chalarosomum.
Behavioral Traits, Sensing and Intelligence: They can inflate their stomachs with water or air to frighten predators. Typically, they fill their cavities with water, but if captured by humans and at the surface, they will inflate with air, and when they deflate, the escaping pressurized air makes the shark sound like it is barking like a dog.
During the day, the Draughtsboard shark is lethargic and typically hides inside crevices or caves on the reef. They are nocturnal, moving to the sandy bottom sat night to forage and hunt.
Adult males and females segregate by sex.
They can tolerate being out of water for an extended period of time.
Draughtsboard Shark Future and Conservation: They are of least concern. They are caught by deep-water trawlers, but discarded. They survive discard well.
From 1988 to 1991, there was a New Zealand shark liver fishery and reported catches of Draughtsboard sharks were 74–540 tons per year. After the fishery was discontinued, catches dropped to under five tons per year.
Draughtsboard Shark Recorded Attacks on Humans: Not a threat to humans.