Draughtsboard shark
Encyclopedia
The draughtsboard shark (Cephaloscyllium isabellum) is a species
of catshark
, family
Scyliorhinidae, so named for its "checkerboard
" color pattern of dark blotches. It is endemic to New Zealand
, where it is also known as the carpet shark (which usually refers to the entire order
Orectolobiformes). This shark typically reaches 1 m (3.3 ft) in length and has a thick body with a broad, flattened head and a capacious mouth. Its two dorsal fins are placed far back on the body, with the first much larger than the second.
Occurring down to a depth of 673 m (2,208 ft), the draughtsboard shark frequents rocky reef
s during the day and sandy flats at night. Its diet consists of fishes and invertebrate
s. When threatened by a predator, it can take water or air into its body to inflate its body, which may be the cause of its unusual habit of barking like a dog
. This species is oviparous, with females laying smooth, tendril-bearing egg capsules in pairs. Draughtsboard sharks are often taken as bycatch
by commercial fisheries, but are probably hardy enough to survive the experience. The International Union for Conservation of Nature (IUCN) has listed this species under Least Concern
.
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
.
The draughtsboard shark closely resembles the blotchy 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 capsules (smooth in C. isabellum and ridged in C. laticeps). It differs from the blotchy swellshark in coloration and morphometric measurements
.
, the Chatham Islands
, and Stewart Island
, where it is particularly common. It typically occurs at depths of 0 to 400 m (0 to 1,312.3 ft) on continental and insular shelves
, though it has been recorded from as far down as 673 m (2,208 ft). This shark is a bottom-dweller that favors rocky reef
s and adjacent areas of soft substrate. Adult males and females segregate from each other.
(Notorynchus cepedianus) or some other species. Females grow larger than males. This shark has a stocky, spindle-shaped body that tapers to a relatively thin caudal peduncle. The head is short, broad, and somewhat flattened, with a broadly rounded snout. The nostril
s 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 thick ridges above and below, and are followed by spiracle
s. The mouth is very large and curved, without furrows at the corners and with the upper teeth exposed when closed.
The pectoral fins are fairly large and broad. The two dorsal fin
s 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, and also smaller than the anal fin. Males have short and thick claspers. 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. The skin is thick and covered by well-calcified
dermal denticles. The coloration of the draughtsboard shark gives it its common name
: it is golden to brown above and light below, with up to 11 dark brown, irregular dorsal "saddles" that alternate with blotches on its flanks to form a checkerboard
pattern. Also distinctive is the saddle between its spiracles, which is stretched out and swept back on each side to form a bar over the gill slits.
, cod
, sand perch, blennies, octopus
, squid
, gastropods, innkeeper worms
, krill
, hermit crab
s, crab
s, spiny lobster
s, and even sea squirts. Individuals 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. A known parasite of this species is the tapeworm Calyptrobothrium chalarosomum.
Like other Cephaloscyllium species, the draughtsboard shark has the ability to inflate its body dramatically in response to a predator; this defense mechanism may be behind reports of this species barking like a large dog
. While it usually inflates with water, when captured by humans and brought to the surface it may inflate with air instead. When the shark deflates, the "bark" is produced by the pressurized air as it is released explosively through the cardiac sphincter of the stomach. This species is oviparous, with females laying two eggs at a time. The smooth, cream-colored egg cases measure 12 cm (4.7 in) long, and have long, spiral tendrils at the corners that allow them to be fastened to underwater objects. Newly hatched sharks measure 16 cm (6.3 in) long; males and females mature sexually at 60 cm (23.6 in) and 80 cm (31.5 in) long respectively.
by trawl, rock lobster
, and probably set net
fisheries. It is likely that most captured sharks survive to be returned to the water alive, as this species can tolerate being out of water for an extended period of time. 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. Because its population seems healthy and free from significant threats, the International Union for Conservation of Nature (IUCN) has assessed this species as of Least Concern
.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of catshark
Catshark
Catsharks are ground sharks of the family Scyliorhinidae, with over 150 known species. While they are generally known as catsharks, many species are commonly called dogfish....
, family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Scyliorhinidae, so named for its "checkerboard
Checkerboard
A checkerboard or chequerboard is a board of chequered pattern on which English draughts is played. It is an 8×8 board and the 64 squares are of alternating dark and light color, often red and black....
" color pattern of dark blotches. It is endemic to New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, where it is also known as the carpet shark (which usually refers to the entire order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Orectolobiformes). This shark typically reaches 1 m (3.3 ft) in length and has a thick body with a broad, flattened head and a capacious mouth. Its two dorsal fins are placed far back on the body, with the first much larger than the second.
Occurring down to a depth of 673 m (2,208 ft), the draughtsboard shark frequents rocky reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s during the day and sandy flats at night. Its diet consists of fishes and invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s. When threatened by a predator, it can take water or air into its body to inflate its body, which may be the cause of its unusual habit of barking like a dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
. This species is oviparous, with females laying smooth, tendril-bearing egg capsules in pairs. Draughtsboard sharks are often taken as bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
by commercial fisheries, but are probably hardy enough to survive the experience. The International Union for Conservation of Nature (IUCN) has listed this species under Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
.
Taxonomy
French naturalistNaturalist
Naturalist may refer to:* Practitioner of natural history* Conservationist* Advocate of naturalism * Naturalist , autobiography-See also:* The American Naturalist, periodical* Naturalism...
Pierre Joseph Bonnaterre
Pierre Joseph Bonnaterre
Abbé Pierre Joseph Bonnaterre was a French naturalist who contributed sections on cetaceans, mammals, birds, reptiles, amphibians, and insects to the Tableau encyclopédique et méthodique...
originally described the draughtsboard shark as Squalus isabella, in the 1788 ichthyology
Ichthyology
Ichthyology is the branch of zoology devoted to the study of fish. This includes skeletal fish , cartilaginous fish , and jawless fish...
volume of the Tableau encyclopédique et méthodique des trois règnes de la nature
Tableau encyclopédique et méthodique
The Tableau encyclopédique et méthodique des trois regnes de la nature was an illustrated encyclopedia of plants, animals and minerals, notable for including the first scientific descriptions of many species, and for its attractive engravings. It was published in Paris by Charles Joseph Panckoucke,...
. 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
Cephaloscyllium
Cephaloscyllium is a genus of catshark, family Scyliorhinidae, commonly known as swellsharks because of their ability to inflate their body with water or air as a defense against predators. These sluggish, bottom-dwelling sharks are found widely in the tropical and temperate coastal waters of the...
.
The draughtsboard shark closely resembles the blotchy swellshark (C. umbratile) and the Australian swellshark
Australian swellshark
The Australian swellshark or draughtboard shark is a species of catshark, family Scyliorhinidae, endemic to southern Australia. This bottom-dwelling species can be found on the continental shelf down to a depth of . Usually measuring long, it is a stout-bodied, broad-headed shark with a short...
(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 capsules (smooth in C. isabellum and ridged in C. laticeps). It differs from the blotchy swellshark in coloration and morphometric measurements
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
.
Distribution and habitat
The draughtsboard shark is found only in the coastal waters around New Zealand, including the SnaresThe Snares
Snares Islands/Tini Heke is a small island group situated approximately 200 kilometres south of New Zealand's South Island and to the south-south-west of Stewart Island/Rakiura. The Snares consist of the main island North East Island and the smaller Broughton Island as well as the somewhat...
, the Chatham Islands
Chatham Islands
The Chatham Islands are an archipelago and New Zealand territory in the Pacific Ocean consisting of about ten islands within a radius, the largest of which are Chatham Island and Pitt Island. Their name in the indigenous language, Moriori, means Misty Sun...
, and Stewart Island
Stewart Island/Rakiura
Stewart Island/Rakiura is the third-largest island of New Zealand. It lies south of the South Island, across Foveaux Strait. Its permanent population is slightly over 400 people, most of whom live in the settlement of Oban.- History and naming :...
, where it is particularly common. It typically occurs at depths of 0 to 400 m (0 to 1,312.3 ft) on continental and insular shelves
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
, though it has been recorded from as far down as 673 m (2,208 ft). This shark is a bottom-dweller that favors rocky reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s and adjacent areas of soft substrate. Adult males and females segregate from each other.
Description
Most draughtsboard sharks measure no more than 1 m (3.3 ft) long, though rarely an individual may reach 1.5 m (4.9 ft); a recorded maximum size of 2.4 m (7.9 ft) was probably based on the broadnose sevengill sharkBroadnose sevengill shark
The broadnose sevengill shark is the only extant member of the genus Notorynchus, in the family Hexanchidae. It is recognizable because of its seven gill slits, while most shark species have five gill slits, with the exception of the members of the order Hexanchiformes and the sixgill sawshark.The...
(Notorynchus cepedianus) or some other species. Females grow larger than males. This shark has a stocky, spindle-shaped body that tapers to a relatively thin caudal peduncle. The head is short, broad, and somewhat flattened, with a broadly rounded snout. The nostril
Nostril
A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...
s 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 thick ridges above and below, and are followed by spiracle
Spiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
s. The mouth is very large and curved, without furrows at the corners and with the upper teeth exposed when closed.
The pectoral fins are fairly large and broad. The two dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
s 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, and also smaller than the anal fin. Males have short and thick claspers. 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. The skin is thick and covered by well-calcified
Calcification
Calcification is the process in which calcium salts build up in soft tissue, causing it to harden. Calcifications may be classified on whether there is mineral balance or not, and the location of the calcification.-Causes:...
dermal denticles. The coloration of the draughtsboard shark gives it its common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
: it is golden to brown above and light below, with up to 11 dark brown, irregular dorsal "saddles" that alternate with blotches on its flanks to form a checkerboard
Checkerboard
A checkerboard or chequerboard is a board of chequered pattern on which English draughts is played. It is an 8×8 board and the 64 squares are of alternating dark and light color, often red and black....
pattern. Also distinctive is the saddle between its spiracles, which is stretched out and swept back on each side to form a bar over the gill slits.
Biology and ecology
During the day, the draughtsboard shark is lethargic and typically hides inside crevices or caves on the reef. At night, it emerges to forage for food over nearby sandy flats. This shark consumes a wide variety of fishes and invertebrates, including spiny dogfishSpiny dogfish
The spiny dogfish, spurdog, mud shark, or piked dogfish, Squalus acanthias, is one of the best known of the dogfish which are members of the family Squalidae in the order Squaliformes. While these common names may apply to several species, Squalus acanthias is distinguished by having two spines ...
, cod
Cod
Cod is the common name for genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of...
, sand perch, blennies, octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...
, squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
, gastropods, innkeeper worms
Echiura
The Echiura, or spoon worms, are a small group of marine animals. They are often considered to be a group of annelids, although they lack the segmented structure found in other members of that group, and so may also be treated as a separate phylum...
, krill
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...
, hermit crab
Hermit crab
Hermit crabs are decapod crustaceans of the superfamily Paguroidea. Most of the 1100 species possess an asymmetrical abdomen which is concealed in an empty gastropod shell that is carried around by the hermit crab.-Description:...
s, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s, spiny lobster
Spiny lobster
Spiny lobsters, also known as langouste or rock lobsters, are a family of about 45 species of achelate crustaceans, in the Decapoda Reptantia...
s, and even sea squirts. Individuals have been observed sucking innkeeper worms out of their burrows, and swimming around with the antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
of large lobsters sticking out of their mouths for hours. A known parasite of this species is the tapeworm Calyptrobothrium chalarosomum.
Like other Cephaloscyllium species, the draughtsboard shark has the ability to inflate its body dramatically in response to a predator; this defense mechanism may be behind reports of this species barking like a large dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
. While it usually inflates with water, when captured by humans and brought to the surface it may inflate with air instead. When the shark deflates, the "bark" is produced by the pressurized air as it is released explosively through the cardiac sphincter of the stomach. This species is oviparous, with females laying two eggs at a time. The smooth, cream-colored egg cases measure 12 cm (4.7 in) long, and have long, spiral tendrils at the corners that allow them to be fastened to underwater objects. Newly hatched sharks measure 16 cm (6.3 in) long; males and females mature sexually at 60 cm (23.6 in) and 80 cm (31.5 in) long respectively.
Human interactions
Common and harmless, draughtsboard sharks are often caught incidentallyBycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
by trawl, rock lobster
Rock lobster
Jasus edwardsii, the southern rock lobster, red rock lobster, or spiny rock lobster, is a species of spiny lobster found throughout coastal waters of southern Australia and New Zealand including the Chatham Islands. This species is commonly called crayfish or crays in New Zealand and in Māori...
, and probably set net
Fishing net
A fishing net or fishnet is a net that is used for fishing. Fishing nets are meshes usually formed by knotting a relatively thin thread. Modern nets are usually made of artificial polyamides like nylon, although nets of organic polyamides such as wool or silk thread were common until recently and...
fisheries. It is likely that most captured sharks survive to be returned to the water alive, as this species can tolerate being out of water for an extended period of time. From 1988 to 1991, there was a New Zealand shark liver
Shark liver oil
Shark liver oil is obtained from sharks that are caught for food purposes and are living in cold, deep oceans. The liver oil from sharks has been used by fishermen for centuries as a folk remedy for general health...
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. Because its population seems healthy and free from significant threats, the International Union for Conservation of Nature (IUCN) has assessed this species as of Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
.