Australian sawtail catshark
Encyclopedia
The Australian sawtail catshark (Figaro boardmani) is a common species
of catshark
, family
Scyliorhinidae, endemic to southern Australia
n waters. It is found on or near the bottom over the outer continental shelf
and upper continental slope, at depths of 85 to 823 m (278.9 to 2,700.1 ft). This slim-bodied species is characterized by crests of enlarged dermal denticles along both the dorsal and ventral edges of its caudal fin and caudal peduncle, along with a color pattern of broad, dark saddles outlined in white. It can grow to 61 cm (24 in) in length. The Australian sawtail catshark feeds mainly on fishes, crustacean
s, and cephalopod
s. Females are oviparous and lay eggs enclosed by capsules. This species is often caught incidentally
by commercial
bottom trawl fisheries, but is not significantly threatened by fishing activity. Thus, it has been assessed as of Least Concern
by the International Union for Conservation of Nature (IUCN).
originally described the Australian sawtail catshark as Pristiurus boardmani, in a 1928 issue of the scientific journal
Records of the Australian Museum, and placed it within his newly created subgenus Figaro. Whitley named the species after his friend and colleague William Boardman, who collected the first known specimens, including the holotype
: a 54 cm (21.3 in) long adult male trawled by the Bar-ea-mul on 18 July 1925, northeast of Montague Island off New South Wales
. Another common name
for this species is banded shark.
Both Pristiurus and Figaro have generally been considered junior synonyms of the genus Galeus
; in 2008, Commonwealth Scientific and Industrial Research Organisation
(CSIRO) researchers Daniel Gledhill, Peter Last, and William White resurrected Figaro, with F. boardmani as the type species
. Whitley regarded sharks from the Great Australian Bight
as representing a distinct subspecies, F. b. socinus, which has not been recognized by subsequent authors. However, individuals from different portions of its range do exihibit minor differences in morphology
and coloration, which merit further study.
, the Australian sawtail catshark has been found from Carnarvon
in Western Australia
to Noosa
in Queensland
, including all of Tasmania
. This abundant, demersal species inhabits the outer continental shelf
and upper continental slope at a depth of 85–823 m (278.9–2,700.1 ft).
s (protective third eyelids). Beneath the eye is a thin ridge, and behind is a tiny spiracle
. The nostrils have triangular flaps of skin in front. The mouth is wide and arched, with furrows of medium length at each corner. The teeth are small, each with a long central cusp and multiple smaller cusplets on each side. There are five pairs of gill slit
s.
The two dorsal fin
s have rounded apexes, with the first slightly larger than the second. The first and second dorsal fins originate over the rear of the pelvic fin and anal fins respectively. The pectoral fins are broad and moderate in size. The pelvic fins are small and low with an angular shape; in adult males their inner margins are fused to form a subtle "apron" over the claspers. The anal fin is roughly triangular; its base measures 11% of the total length, exceeding the distance between the pelvic and anal fins but not the distance between the dorsal fins. The caudal fin is short and low, with a small but obvious lower lobe and a ventral notch near the tip of the upper lobe. Small, overlapping dermal denticles cover the body and fins; each denticle has three marginal teeth. In addition, there are enlarged spiny denticles forming prominent crests along the front half of the upper caudal fin edge, and beneath the caudal peduncle to the ventral caudal fin edge. This species is grayish above and light below. Dorsally, there are 12–13 variegated dark saddles or bands along the body and tail, including three saddles before the dorsal fins that are separated by narrow bands. The saddles are highlighted by a lighter edge, and may contain white flecks. The dorsal and pectoral fins are dark at the bases and light at the margins.
s, and cephalopod
s. Reproduction is oviparous, possibly without a well-defined breeding season
as is the case in other catsharks. Adult females have a single functional ovary
and two functional oviduct
s; apparently a single egg matures in each oviduct at a time. The eggs are enclosed in capsules measuring 6.8–7.4 cm (2.7–2.9 in) long, 1.9–2 cm (0.748031496062992–0.78740157480315 in) across, and 8–9 cm (3.1–3.5 in) thick. Males and females attain sexual maturity
at roughly 40 cm (15.7 in) and 40–43 cm (15.7–16.9 in) long respectively.
of bottom trawl commercial fisheries
operating throughout its range, including the Western Australian Deep Water Trawl Fishery, the South East Trawl Fishery, and the Queensland East Coast Trawl Fishery. It may be retained and utilized, but is more commonly discarded; the survival rate of discarded sharks is unknown. This species remains widespread and common, and fishing activities do not appear to pose a substantial threat to its population at present. As a result, the International Union for Conservation of Nature (IUCN) has listed it under 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, endemic to southern Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n waters. It is found on or near the bottom over the outer continental shelf
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,...
and upper continental slope, at depths of 85 to 823 m (278.9 to 2,700.1 ft). This slim-bodied species is characterized by crests of enlarged dermal denticles along both the dorsal and ventral edges of its caudal fin and caudal peduncle, along with a color pattern of broad, dark saddles outlined in white. It can grow to 61 cm (24 in) in length. The Australian sawtail catshark feeds mainly on fishes, crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, and cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s. Females are oviparous and lay eggs enclosed by capsules. This species is often caught incidentally
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
Commercial fishing
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...
bottom trawl fisheries, but is not significantly threatened by fishing activity. Thus, it has been assessed 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...
by the International Union for Conservation of Nature (IUCN).
Taxonomy
Australian ichthyologist Gilbert Percy WhitleyGilbert Percy Whitley
Gilbert Percy Whitley was a British-born Australian ichthyologist and malacologist who was Curator of Fishes at the Australian Museum in Sydney for about 40 years. He was born at Swaythling, Southampton, England, and was educated at King Edward VI School, Southampton and Osborne House...
originally described the Australian sawtail catshark as Pristiurus boardmani, in a 1928 issue of the scientific journal
Scientific journal
In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. There are thousands of scientific journals in publication, and many more have been published at various points in the past...
Records of the Australian Museum, and placed it within his newly created subgenus Figaro. Whitley named the species after his friend and colleague William Boardman, who collected the first known specimens, including the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
: a 54 cm (21.3 in) long adult male trawled by the Bar-ea-mul on 18 July 1925, northeast of Montague Island off New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
. Another 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...
for this species is banded shark.
Both Pristiurus and Figaro have generally been considered junior synonyms of the genus Galeus
Galeus
Galeus is a genus of catshark, family Scyliorhinidae, commonly known as sawtail catsharks in reference to a distinctive saw-toothed crest of enlarged dermal denticles found along the upper edges of their caudal fins. They are found in the Atlantic, the western and central Pacific, and the Gulf of...
; in 2008, Commonwealth Scientific and Industrial Research Organisation
Commonwealth Scientific and Industrial Research Organisation
The Commonwealth Scientific and Industrial Research Organisation is the national government body for scientific research in Australia...
(CSIRO) researchers Daniel Gledhill, Peter Last, and William White resurrected Figaro, with F. boardmani as the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
. Whitley regarded sharks from the Great Australian Bight
Great Australian Bight
The Great Australian Bight is a large bight, or open bay, off the central and western portions of the southern coastline of mainland Australia.-Extent:...
as representing a distinct subspecies, F. b. socinus, which has not been recognized by subsequent authors. However, individuals from different portions of its range do exihibit minor differences in morphology
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....
and coloration, which merit further study.
Distribution and habitat
Widely distributed off southern AustraliaAustralia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, the Australian sawtail catshark has been found from Carnarvon
Carnarvon, Western Australia
Carnarvon is a coastal town situated approximately 900 kilometres north of Perth, Western Australia. It lies at the mouth of the Gascoyne River on the Indian Ocean. The popular Shark Bay world heritage area lies to the south of the town and the Ningaloo Reef lies to the north...
in Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
to Noosa
Noosa, Queensland
The Shire of Noosa was a Local Government Area located about north of Brisbane in the Sunshine Coast region of South East Queensland, Australia...
in Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, including all of Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
. This abundant, demersal species inhabits the outer continental shelf
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,...
and upper continental slope at a depth of 85–823 m (278.9–2,700.1 ft).
Description
The maximum known length of the Australian sawtail catshark is 61 cm (24 in). Its slender body is firm and nearly cylindrical in cross-section. The snout is rather short and narrow, with a somewhat angular profile from above. The eyes are horizontally oval and equipped with rudimentary nictitating membraneNictitating membrane
The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten it while maintaining visibility. Some reptiles, birds, and sharks have a full nictitating membrane; in many mammals, there is a small...
s (protective third eyelids). Beneath the eye is a thin ridge, and behind is a tiny 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...
. The nostrils have triangular flaps of skin in front. The mouth is wide and arched, with furrows of medium length at each corner. The teeth are small, each with a long central cusp and multiple smaller cusplets on each side. There are five pairs of gill slit
Gill slit
Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of Cartilaginous fish such as sharks, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
s.
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 have rounded apexes, with the first slightly larger than the second. The first and second dorsal fins originate over the rear of the pelvic fin and anal fins respectively. The pectoral fins are broad and moderate in size. The pelvic fins are small and low with an angular shape; in adult males their inner margins are fused to form a subtle "apron" over the claspers. The anal fin is roughly triangular; its base measures 11% of the total length, exceeding the distance between the pelvic and anal fins but not the distance between the dorsal fins. The caudal fin is short and low, with a small but obvious lower lobe and a ventral notch near the tip of the upper lobe. Small, overlapping dermal denticles cover the body and fins; each denticle has three marginal teeth. In addition, there are enlarged spiny denticles forming prominent crests along the front half of the upper caudal fin edge, and beneath the caudal peduncle to the ventral caudal fin edge. This species is grayish above and light below. Dorsally, there are 12–13 variegated dark saddles or bands along the body and tail, including three saddles before the dorsal fins that are separated by narrow bands. The saddles are highlighted by a lighter edge, and may contain white flecks. The dorsal and pectoral fins are dark at the bases and light at the margins.
Biology and ecology
The Australian sawtail catshark has been known to assemble in groups of a single sex. It feeds primarily on fishes, crustaceanCrustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, and cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s. Reproduction is oviparous, possibly without a well-defined breeding season
Breeding season
The breeding season is the most suitable season, usually with favourable conditions and abundant food and water, for breeding among some wild animals and birds . Species with a breeding season have naturally evolved to have sexual intercourse during a certain time of year in order to achieve the...
as is the case in other catsharks. Adult females have a single functional ovary
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
and two functional oviduct
Oviduct
In non-mammalian vertebrates, the passageway from the ovaries to the outside of the body is known as the oviduct. The eggs travel along the oviduct. These eggs will either be fertilized by sperm to become a zygote, or will degenerate in the body...
s; apparently a single egg matures in each oviduct at a time. The eggs are enclosed in capsules measuring 6.8–7.4 cm (2.7–2.9 in) long, 1.9–2 cm (0.748031496062992–0.78740157480315 in) across, and 8–9 cm (3.1–3.5 in) thick. Males and females attain sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at roughly 40 cm (15.7 in) and 40–43 cm (15.7–16.9 in) long respectively.
Human interactions
The Australian sawtail catshark is a frequent incidental catchBycatch
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...
of bottom trawl commercial fisheries
Commercial fishing
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...
operating throughout its range, including the Western Australian Deep Water Trawl Fishery, the South East Trawl Fishery, and the Queensland East Coast Trawl Fishery. It may be retained and utilized, but is more commonly discarded; the survival rate of discarded sharks is unknown. This species remains widespread and common, and fishing activities do not appear to pose a substantial threat to its population at present. As a result, the International Union for Conservation of Nature (IUCN) has listed it 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...
.