The blind shark (''Brachaelurus waddi'') is one of two

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

carpet shark Carpet sharks are sharks classified in the order Orectolobiformes . Sometimes the common name "carpet shark" (named so because many species resemble ornately patterned carpets) is used interchangeably with "wobbegong", which is the common name o ...

s in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Brachaeluridae ''Brachaelurus'' (blind sharks) is the sole genus of sharks in the family Brachaeluridae in the order Orectolobiformes. Only two species of blind sharks occur, both of which are native to shallow coastal waters up to deep, off the eastern coast ...

, along with the bluegrey carpetshark (''Brachaelurus colcloughi''). Found along the coast of eastern

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, this

nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

, bottom-dwelling species is common in rocky areas and

seagrass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the orde ...

beds from the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...

to a depth of . It often roams in

tidal pool A tide pool or rock pool is a shallow pool of seawater that forms on the rocky intertidal shore. Many of these pools exist as separate bodies of water only at low tide. Many tide pool habitats are home to especially adaptable animals that ...

s where it may be trapped by the receding tide, and can survive for an extended period out of water. Maturing at under long, the blind shark has a stocky, grayish to brownish body with white flecks and darker bands that fade with age. Its head is wide, flattened, and blunt, with small eyes on top and a pair of long barbels underneath. It has large

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

s, two nearly equal-sized

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

s placed far back on the body, and an

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

placed close to the

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

. The blind shark feeds primarily on small

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s and

bony fish Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilag ...

es. It is

aplacental viviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...

with females bearing litters of 7–8 pups in the summer. This small shark adapts readily to being kept in captivity. It is not valued by either

commercial Commercial may refer to: * a dose of advertising conveyed through media (such as - for example - radio or television) ** Radio advertisement ** Television advertisement * (adjective for:) commerce, a system of voluntary exchange of products and s ...

or recreational fishers, and its hardiness means that incidentally caught individuals are likely to be returned to the water alive. In the absence of substantial threats to its population, the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

has assessed it as of

Least Concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

Taxonomy and phylogeny

German naturalists

Marcus Elieser Bloch Marcus Elieser Bloch (1723–1799) was a German physician and naturalist who is best known for his contribution to ichthyology through his multi-volume catalog of plates illustrating the fishes of the world. Brought up in a Hebrew-speaking Jewish ...

and

Johann Gottlob Schneider Johann Gottlob Theaenus Schneider (18 January 1750 – 12 January 1822) was a German Empire, German classicist and natural history, naturalist. Biography Schneider was born at Collm in Saxony. In 1774, on the recommendation of Christian Gottlob ...

originally described the blind shark as ''Squalus waddi'', in their 1801 ''Systema Ichthyologiae''. However, there is uncertainty over whether their account was referring to this species or the

brownbanded bamboo shark The brownbanded bamboo shark (''Chiloscyllium punctatum''), is a bamboo shark in the family Hemiscylliidae that can be found in the Indo-West Pacific from Japan to northern Australia, between latitudes 34° N and 26° S. It is regularly bred i ...

(''Chiloscyllium punctatum''), as it was based on a painting by John Latham that could not be located by subsequent authors. In 1907,

James Douglas Ogilby James Douglas Ogilby (16 February 1853 – 11 August 1925) was an Australian ichthyologist and herpetologist. Ogilby was born in Belfast, Ireland, and was the son of zoologist William Ogilby and his wife Adelaide, née Douglas. He received h ...

coined the genus ''Brachaelurus'' for this species, from the Greek ''brachys'' meaning "short", and ''ailouros'' meaning "cat". In 1973,

Leonard Compagno Leonard Joseph Victor Compagno is an international authority on shark taxonomy and the author of many scientific papers and books on the subject, best known of which is his 1984 catalogue of shark species produced for the Food and Agriculture Organi ...

placed it and the bluegrey carpetshark in their own family. This shark may also be referred to as the brown catshark or dusky dogfish. Various

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

studies, based on

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

, have concluded that the blind shark lineage represents the sister

taxon In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

to the

wobbegong The wobbegong is the common name given to the 12 species of carpet sharks in the family Orectolobidae. They are found in shallow temperate and tropical waters of the western Pacific Ocean and eastern Indian Ocean, chiefly around Australia and I ...

s. Blind shark

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s have been found in

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

(99.6–65.5 Ma) deposits from

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

, as well as in

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

(5.3–2.6 Ma) deposits from

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

and

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

. A number of other ''

Brachaelurus ''Brachaelurus'' (blind sharks) is the sole genus of sharks in the family Brachaeluridae in the order Orectolobiformes. Only two species of blind sharks occur, both of which are native to shallow coastal waters up to deep, off the eastern coast ...

'' species are also known from the fossil record.

Distribution and habitat

The range of the blind shark is restricted to the eastern coast of

, from

Mooloolaba Mooloolaba is a coastal suburb of Maroochydore in the Sunshine Coast Region, Queensland, Australia. It is located north of the state capital, Brisbane, and is part of the Maroochydore urban centre. In the , Mooloolaba had a population of 7,730 ...

in southern

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

Jervis Bay Jervis Bay () is a oceanic bay and village on the south coast of New South Wales, Australia, said to possess the whitest sand in the world. A area of land around the southern headland of the bay is a territory of the Commonwealth of Australia ...

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

; past reports from off

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

and

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...

appear to be misidentifications of the brownbanded bamboo shark. The blind shark is a bottom-dwelling species that generally inhabits the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

from the

, including

s barely deep enough to cover its body, to a depth of , though it has been recorded as deep as . Preferred habitats are rocky areas and adjacent

beds; juveniles are common in high-energy surge zones. In

Nelson Bay Nelson Bay may refer to: *Nelson Bay, New South Wales *Nelson Bay, Tasmania * Nelson Bay, Alaska *Nelson Bay Cave Nelson Bay Cave also known as Wagenaar's Cave is a Stone Age archaeological site located in the Robberg Nature Reserve on the Ro ...

, this shark has been observed lying in the open atop

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...

Description

The blind shark has a stocky body and a wide, somewhat flattened head with a blunt snout. The small, oval eyes are situated high on the head and have strong ridges underneath; the oval

spiracle Spiracle or spiraculum may refer to: * Spiracle (arthropods), opening in the exoskeletons of some arthropods * Spiracle (vertebrates), openings on the surface of some vertebrates * Spiraculum, a genus of land snails in family Cyclophoridae Cycl ...

s are positioned behind and below and have obvious raised rims. The

nostril A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...

s are placed almost at the tip of the snout and have long, tapering barbels in front and well-developed skin flaps and grooves around the incurrent openings. A pair of obvious grooves connect the nostrils to the small, almost transverse mouth. There are 32–34 upper tooth rows and 21–29 lower tooth rows; each tooth has an upright, awl-shaped central cusp and a pair of lateral cusplets. The five pairs of

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 and rays, as well as deep-branching vertebrates such as lampreys. In con ...

s are small, with the fifth pair close to the fourth. The

s are large and broad, with rounded margins. The two

s are roughly equal in size and have rounded apices and angular free rear tips; the first dorsal fin originates over the bases of the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

s. The pelvic fins are rounded and almost as large as the pectoral fins. The

is less than half the size of the dorsal fins and is positioned very close to the base of the long, low

. The caudal fin comprises about a quarter of the total length, with no ventral lobe and a strong ventral notch near the tip of the upper lobe. The

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as we ...

s are large, giving the skin a rough texture. This species is light to dark brown above, often with white flecks, and lighter below. Juveniles also have dark bands over the body and tail, which fade with age. The blind shark can reach a length of , though most are much smaller.

Biology and ecology

Contrary to its

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

, the blind shark has "perfectly adequate" vision. It was so named by anglers because it retracts its

eyeball Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conve ...

s and shuts its thick lower

eyelid An eyelid is a thin fold of skin that covers and protects an eye. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision. This can be either voluntarily or involuntarily. The human eyel ...

s when removed from the water. This species can live for up to 18 hours out of water, allowing it to survive being stranded by the outgoing tide. The blind shark is secretive and sluggish during the day, with adults usually hiding in caves or under ledges and juveniles inside crevices, though it will take food given the opportunity. At night, it moves out over reefs and

seagrass meadow A seagrass meadow or seagrass bed is an underwater ecosystem formed by seagrasses. Seagrasses are marine (saltwater) plants found in shallow coastal waters and in the brackish waters of estuaries. Seagrasses are flowering plants with stems and ...

s to forage for small

s (including

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s, and

sea anemone Sea anemones are a group of predation, predatory marine invertebrates of the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemones are classifi ...

s) and

es. Prey items are captured via suction. Brachaelurus waddi

The blind shark is

with a possibly annual reproductive cycle. Females give birth to 7–8 pups during the summer; newborns measure long.

Sexual maturity Sexual maturity is the capability of an organism to reproduce. In humans it might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definitio ...

is attained at under a length of for males, and for females. It has lived to 20 years old in captivity. A known

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

of this shark is an undescribed species of

tapeworm Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass is Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cestodar ...

in the genus ''Carpobothrium''.

Human interactions

The blind shark is basically harmless to humans, though it can bite if provoked and is difficult to remove, owing to its strong jaws and powerful suction. There are cases of blind sharks biting and holding onto divers'

wetsuit A wetsuit is a garment worn to provide thermal protection while wet. It is usually made of foamed neoprene, and is worn by surfing, surfers, Underwater diving, divers, windsurfers, canoeists, and others engaged in water sports and other activit ...

s even after they surfaced, and could only be removed by prying open the sharks' jaws. This species is one of the few sharks considered suitable for private aquaria, as it is hardy, grows to a small size, and has sedentary habits, though its nocturnal, reclusive nature make it difficult to observe. The blind shark has even been induced to breed in captivity, with the

Sydney Aquarium SEA LIFE Sydney Aquarium (formerly Sydney Aquarium) is a public aquarium A public aquarium (plural: ''public aquaria'' or ''public Water Zoo'') is the aquatic counterpart of a zoo, which houses living aquatic animal and plant specimens fo ...

having successfully maintained a breeding colony.

Commercial fisheries 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 ...

do not target or utilize the blind shark, as its flesh has a strong

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...

-like taste that is not easily removed. It is caught incidentally by

prawn Prawn is a common name for small aquatic crustaceans with an exoskeleton and ten legs (which is a member of the order decapoda), some of which can be eaten. The term "prawn"Mortenson, Philip B (2010''This is not a weasel: a close look at nature ...

trawl Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch different speci ...

and other fisheries off Queensland and New South Wales, though post-discard survival may be high due to its ability to tolerate being out of water. Small numbers of blind sharks are caught by recreational fishers, who regard them as a nuisance because its small mouth and strong jaws make removing lodged hooks difficult. It is generally too small to be susceptible to

shark net A shark net is a submerged section of gillnets placed at beaches designed to intercept large marine animals including sharks, with the aim to reduce the likelihood of shark attacks on swimmers. Shark nets used are gillnets which is a wall of net ...

s used to protect beaches. The impact of collection for the aquarium trade on this shark is unknown but not thought to be severe. The

(IUCN) has listed the blind shark under

, as it remains abundant and the various pressures on its population do not seem to pose significant threats. Its range overlaps a number of current and proposed

Marine Protected Area Marine protected areas (MPA) are protected areas of seas, oceans, estuaries or in the US, the Great Lakes. These marine areas can come in many forms ranging from wildlife refuges to research facilities. MPAs restrict human activity for a conserv ...

s (MPAs).

References

{{DEFAULTSORT:shark, blind

blind shark The blind shark (''Brachaelurus waddi'') is one of two species of carpet sharks in the family Brachaeluridae, along with the bluegrey carpetshark (''Brachaelurus colcloughi''). Found along the coast of eastern Australia, this nocturnal, botto ...