Blind shark

Last updated

Blind shark
Temporal range: Late Cretaceous–Recent [1]
Blindshark.jpg
Off Nelson Bay, New South Wales
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Orectolobiformes
Family: Brachaeluridae
Genus: Brachaelurus
Species:
B. waddi
Binomial name
Brachaelurus waddi
Brachaelurus waddi distmap.png
Range of the blind shark
Synonyms

Chiloscyllium furvumMacleay, 1881
Chiloscyllium fuscumParker & Haswell, 1897
Chiloscyllium modestumGünther, 1872
Squalus waddiBloch & J. G. Schneider, 1801

Contents

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, bottom-dwelling species is common in rocky areas and seagrass beds from the intertidal zone to a depth of 140 m (460 ft). It often roams in tidal pools where it may be trapped by the receding tide, and can survive for an extended period out of water.

Maturing at under 62–66 cm (24–26 in) 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 fins, two nearly equal-sized dorsal fins placed far back on the body, and an anal fin placed close to the caudal fin. The blind shark feeds primarily on small invertebrates and bony fishes. It is aplacental viviparous with females bearing litters of 78 pups in the summer. This small shark adapts readily to being kept in captivity. It is not valued by either commercial 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 has assessed it as of Least Concern.

Taxonomy and phylogeny

German naturalists Marcus Elieser Bloch and Johann Gottlob Schneider 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 (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 coined the genus Brachaelurus for this species, from the Greek brachys meaning "short", and ailouros meaning "cat". [3] In 1973, Leonard Compagno placed it and the bluegrey carpetshark in their own family. [4] This shark may also be referred to as the brown catshark or dusky dogfish. [5]

Various phylogenetic studies, based on morphology, have concluded that the blind shark lineage represents the sister taxon to the wobbegongs. [6] Blind shark fossils have been found in Late Cretaceous period (99.665.5 Ma) deposits from Europe, as well as in Pliocene epoch (5.32.6 Ma) deposits from Chile and Peru. A number of other Brachaelurus species are also known from the fossil record. [1]

Distribution and habitat

The blind shark favors rocky habitats. Blind shark byron bay.jpg
The blind shark favors rocky habitats.

The range of the blind shark is restricted to the eastern coast of Australia, from Mooloolaba in southern Queensland to Jervis Bay in New South Wales; past reports from off Western Australia and Northern Territory appear to be misidentifications of the brownbanded bamboo shark. [2] The blind shark is a bottom-dwelling species that generally inhabits the continental shelf from the intertidal zone, including tidal pools barely deep enough to cover its body, to a depth of 73 m (240 ft), though it has been recorded as deep as 140 m (460 ft). [4] [5] Preferred habitats are rocky areas and adjacent seagrass beds; juveniles are common in high-energy surge zones. [2] In Nelson Bay, this shark has been observed lying in the open atop sponges. [7]

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 spiracles are positioned behind and below and have obvious raised rims. The nostrils 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 3234 upper tooth rows and 2129 lower tooth rows; each tooth has an upright, awl-shaped central cusp and a pair of lateral cusplets. The five pairs of gill slits are small, with the fifth pair close to the fourth. [4] [8]

The pectoral fins are large and broad, with rounded margins. The two dorsal fins 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 fins. The pelvic fins are rounded and almost as large as the pectoral fins. The anal fin is less than half the size of the dorsal fins and is positioned very close to the base of the long, low caudal fin. 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 denticles are large, giving the skin a rough texture. [4] [8] 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. [9] The blind shark can reach a length of 0.9–1.2 m (3.0–3.9 ft), though most are much smaller. [4]

Biology and ecology

Contrary to its common name, the blind shark has "perfectly adequate" vision. [10] It was so named by anglers because it retracts its eyeballs and shuts its thick lower eyelids when removed from the water. [4] This species can live for up to 18 hours out of water, allowing it to survive being stranded by the outgoing tide. [9] 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 meadows to forage for small invertebrates (including crabs, shrimp, cephalopods, and sea anemones) and bony fishes. Prey items are captured via suction. [2] [4]

Illustration of a blind shark fetus, with the yolk sac not yet completely absorbed. Brachaelurus waddi.jpg
Illustration of a blind shark fetus, with the yolk sac not yet completely absorbed.

The blind shark is aplacental viviparous with a possibly annual reproductive cycle. [2] Females give birth to 78 pups during the summer; newborns measure 15–18 cm (5.9–7.1 in) long. Sexual maturity is attained at under a length of 62 cm (24 in) for males, and 66 cm (26 in) for females. [4] It has lived to 20 years old in captivity. [10] A known parasite of this shark is an undescribed species of tapeworm in the genus Carpobothrium. [11]

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. [8] [9] There are cases of blind sharks biting and holding onto divers' wetsuits even after they surfaced, and could only be removed by prying open the sharks' jaws. [7] 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 having successfully maintained a breeding colony. [10]

Commercial fisheries do not target or utilize the blind shark, as its flesh has a strong ammonia-like taste that is not easily removed. It is caught incidentally by prawn trawl 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 nets used to protect beaches. The impact of collection for the aquarium trade on this shark is unknown but not thought to be severe. [2] [4] The International Union for Conservation of Nature (IUCN) has listed the blind shark under Least Concern, 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 Areas (MPAs). [2]

See also

Related Research Articles

<span class="mw-page-title-main">Carpet shark</span> Order of sharks

Carpet sharks are sharks classified in the order Orectolobiformes. Sometimes the common name "carpet shark" is used interchangeably with "wobbegong", which is the common name of sharks in the family Orectolobidae. Carpet sharks have five gill slits, two spineless dorsal fins, and a small mouth that does not extend past the eyes. Many species have barbels.

<span class="mw-page-title-main">Narcinidae</span> Family of cartilaginous fishes

Narcinidae, or numbfishes, are a family of electric rays. They are bottom-dwelling cartilaginous fishes with large, rounded pectoral fin discs and long tails. They can produce an electric discharge for defense, from which their scientific name is derived.

<span class="mw-page-title-main">Horn shark</span> Species of shark

The horn shark is a species of bullhead shark, in the family Heterodontidae. It is endemic to the coastal waters off the western coast of North America, from California to the Gulf of California. Young sharks are segregated spatially from the adults, with the former preferring deeper sandy flats and the latter preferring shallower rocky reefs or algal beds. A small species typically measuring 1 m (3.3 ft) in length, the horn shark can be recognized by a short, blunt head with ridges over its eyes, two high dorsal fins with large spines, and a brown or gray coloration with many small dark spots.

<span class="mw-page-title-main">Tawny nurse shark</span> Species of shark

The tawny nurse shark is a species of carpet shark in the family Ginglymostomatidae, and the only extant member of the genus Nebrius.

<span class="mw-page-title-main">Crested bullhead shark</span> Species of shark

The crested bullhead shark is an uncommon species of bullhead shark, in the family Heterodontidae. It lives off the coast of eastern Australia from the coast to a depth of 93 m (305 ft). This shark can be distinguished from other members of its family by the large size of the ridges above its eyes and by its color pattern of large dark blotches. It typically attains a length of 1.2 m (3.9 ft).

<span class="mw-page-title-main">Japanese bullhead shark</span> Species of shark

The Japanese bullhead shark is a species of bullhead shark in the family Heterodontidae found in the northwestern Pacific Ocean off the coasts of Japan, Korea, and China. This benthic shark occurs at depths of 6–37 m (20–121 ft) over rocky bottoms or kelp beds. Measuring up to 1.2 m (3.9 ft) long, it can be identified by its short, blunt head, two high dorsal fins with anterior spines, and pattern of irregularly shaped, vertical brown bands and stripes. The Japanese bullhead shark is a docile, slow-swimming species that feeds mainly on shelled invertebrates and small bony fishes. Reproduction is oviparous, with females laying spiral-flanged eggs in communal "nests". This species is of little interest to fisheries.

<span class="mw-page-title-main">Bluegrey carpetshark</span> Species of shark

The bluegrey carpetshark or Colclough's shark, is an uncommon species of carpet shark endemic to shallow inshore waters off northeastern Australia. It is one of the two extant members of the family Brachaeluridae. The bluegrey carpetshark has a stocky body with a wide, slightly flattened head, dorsally placed eyes, and a pair of long barbels with posterior skin flaps. It has large pectoral fins, two dorsal fins of unequal size placed far back on the body, and a sizable space between the anal fin and the base of the caudal fin. Growing to 76 cm (30 in) long, this species has a black-and-white color pattern as a juvenile, which largely fades with age such as that adults are brownish.

<i>Brachaelurus</i> Genus of sharks

Brachaelurus 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 110 m (360 ft) deep, off the eastern coast of Australia.

<span class="mw-page-title-main">Epaulette shark</span> Species of longtailed carpet shark

The epaulette shark is a species of longtailed carpet shark, family Hemiscylliidae, found in shallow, tropical waters off Australia and New Guinea. The common name of this shark comes from the very large, white-margined black spot behind each pectoral fin, which are reminiscent of military epaulettes. A small species usually under 1 m (3.3 ft) long, the epaulette shark has a slender body with a short head and broad, paddle-shaped paired fins. The caudal peduncle comprises over half the shark's length. Adults are light brown above, with scattered darker spots and indistinct saddles.

<span class="mw-page-title-main">Smalleye pygmy shark</span> Species of shark

The smalleye pygmy shark is a little-known species of squaliform shark in the family Dalatiidae, found in water 150–2,000 m (490–6,560 ft) deep near Japan, the Philippines, and Australia. It migrates vertically daily, spending the day in deep water and the night in shallower water. One of the smallest shark species, the smalleye pygmy shark is known to reach only 22 cm (8.7 in) long. It has a blackish, spindle-shaped body with relatively small eyes, and a spine preceding the first dorsal fin, but not the second. Bioluminescent photophores occur on its underside, which may serve to disguise its silhouette from predators. This species feeds on small squid, krill, shrimp, and bony fishes. It is aplacental viviparous. The International Union for Conservation of Nature has assessed it as Least Concern, citing its wide distribution and lack of threat from fisheries.

<span class="mw-page-title-main">Spined pygmy shark</span> Species of shark

The spined pygmy shark is a species of squaliform shark in the family Dalatiidae found widely in all oceans. Growing no larger than roughly 28 cm (11 in), it is one of the smallest sharks alive, with this record beaten by the dwarf lanternshark. This shark has a slender, cigar-shaped body with a sizable conical snout, a long but low second dorsal fin, and an almost symmetrical caudal fin. Its sister species S. aliae and it are the only sharks with a spine on the first dorsal fin and not the second. Spined pygmy sharks are dark brown to black, with numerous bioluminescent organs called photophores on their ventral surface. The shark is believed to use these photophores to match ambient light conditions, which break up its silhouette and help the shark to avoid being seen by predators below.

<span class="mw-page-title-main">Banded houndshark</span> Species of shark

The banded houndshark is a species of houndshark in the family Triakidae, common in the northwestern Pacific Ocean from the southern Russian Far East to Taiwan. Found on or near the bottom, it favors shallow coastal habitats with sandy or vegetated bottoms, and also enters brackish water. This shark reaches 1.5 m (4.9 ft) in length. It has a short, rounded snout and mostly narrow fins; the pectoral fins are broad and triangular, and the trailing margin of the first dorsal fin is almost vertical. It is gray above and lighter below; younger sharks have darker saddles and dots, which fade with age.

<span class="mw-page-title-main">Southern African frilled shark</span> Species of shark

The southern African frilled shark is a species of shark in the family Chlamydoselachidae, described in 2009. It is found in the deep waters off southern Angola to southern Namibia. This species is difficult to distinguish from the better-known frilled shark, but is smaller at maturity and differs in several proportional measurements including head length and mouth width. It seems to be a specialized predator of smaller sharks, using its flexible jaws and numerous needle-like, recurved teeth to capture and swallow them whole. Reproduction is presumably aplacental viviparous, as with the other member of its family.

<span class="mw-page-title-main">Dwarf sawtail catshark</span> Species of shark

The dwarf sawtail catshark is a little-known species of catshark, belonging to the family Scyliorhinidae, found exclusively in the deep waters off Luzon in the Philippines. Unlike other members of its genus, this slender, diminutive shark has a short, rounded snout and very short furrows at the corners of its jaws. It has indistinct darker saddles beneath each dorsal fin and two dark bands on the caudal fin, as well as a prominent crest of enlarged dermal denticles along the upper caudal fin margin.

<span class="mw-page-title-main">Green lanternshark</span> Species of shark

The green lanternshark is a species of dogfish shark in the family Etmopteridae, found in the western central Atlantic Ocean. This species usually occurs on the upper continental slope below a depth of 350 m (1,150 ft). Reaching 26 cm (10 in) in length, the green lanternshark has a slender body with a long, thin tail and low, conical dermal denticles on its flanks. It is dark brown or gray with ventral black coloration, which contain light-emitting photophores that may serve a cryptic and/or social function. Green lanternsharks are thought to be gregarious and may attack their prey, squid and octopus often larger than themselves, in packs. Reproduction is aplacental viviparous, with females giving birth to litters of one to three young. This relatively common shark is an occasional, valueless bycatch of commercial fisheries; currently it does not appear to be significantly threatened by human activities.

<span class="mw-page-title-main">Arabian carpetshark</span> Species of shark

The Arabian carpetshark is a species of carpet shark in the family Hemiscylliidae, inhabiting coral reefs and other shallow coastal habitats from the Persian Gulf to India. Reaching 78 cm (31 in) long, this shark is characterized by a slender, plain brown body, and by two dorsal fins with straight trailing margins and the second smaller but longer-based than the first. The Arabian carpetshark feeds on bony fishes and invertebrates. Reproduction is oviparous with an annual cycle; females deposit egg capsules four at a time and the young hatch after 70–80 days. This small shark is often captured as bycatch but rarely used by humans. It has been assessed as Near Threatened by the International Union for Conservation of Nature (IUCN), as there is increasing fishing pressure and habitat degradation within its range. It does well in aquariums and has been bred in captivity.

<span class="mw-page-title-main">Coffin ray</span> Species of cartilaginous fish

Hypnos monopterygius, also known as the coffin ray or Australian numbfish, is a species of electric ray endemic to Australia, where it is common in inshore waters shallower than 80 m (260 ft). It is the sole member of its genus Hypnos, and family Hypnidae. This small species typically reaches 40 cm (16 in) in length. Greatly enlarged pectoral fins and an extremely short tail, coupled with diminutive dorsal and caudal fins all concentrated towards the rear, give the coffin ray a distinctive pear-like shape. It is a varying shade of brown in color above, and has tiny eyes and a large, highly distensible mouth.

<span class="mw-page-title-main">Striped stingaree</span> Species of cartilaginous fish

The striped stingaree is a common but little-known species of stingray in the family Urolophidae, endemic to shallow, inshore waters off southwestern Australia. Reaching 61 cm (24 in) long, this species is characterized by an oval, grayish to brownish disc with darker mask-like markings around the eyes and paired blotches at the center of the disc that are extended posteriorly into horizontal lines. Its nostrils have enlarged lobes on the outer margins and a skirt-shaped curtain of skin with a deeply fringed trailing margin in between. Its tail terminates in a relatively large leaf-shaped caudal fin, and bears a small dorsal fin just before the stinging spine. The rounded, flexible disc of the striped stingaree enable it to maneuver through the rocks, reefs, and seagrass that comprise its favored habitats. The International Union for Conservation of Nature (IUCN) has listed this species under Least Concern; it is seldom caught by fisheries due to its habitat preferences.

<span class="mw-page-title-main">Wide stingaree</span> Species of cartilaginous fish

The wide stingaree is a little-known species of stingray in the family Urolophidae, found off southwestern Australia. It typically occurs over sand in water 200–300 m (660–980 ft) deep around the edge of the continental shelf. This species has a broad diamond-shaped pectoral fin disc, a slightly pointed snout, and a tail with a leaf-like caudal fin, skin folds along either side, and no dorsal fins. Between its nostrils is a skirt-shaped curtain of skin. It is grayish green above, with faint bluish lines beside and behind the eyes. The maximum length on record is 52 cm (20 in).

The lobed stingaree is a common species of stingray in the family Urolophidae, endemic to southern Western Australia in shallow, inshore sand and seagrass habitats. This species is plain sandy in color above and has a broad, rounded pectoral fin disc. It is characterized by an enlarged, semicircular skin lobe of unknown function on the inner rim of each nostril. Its tail is slender, with lateral skin folds and a lance-like caudal fin but no dorsal fin. The maximum recorded width is 27 cm (11 in).

References

  1. 1 2 Williams, G.S. (1999). A Listing of Fossil Sharks and Rays of the World. Retrieved 30 January 2010.
  2. 1 2 3 4 5 6 7 Kyne, P.M.; Bennett, M.B. (2015). "Brachaelurus waddi". IUCN Red List of Threatened Species . 2015: e.T41732A68610784. doi: 10.2305/IUCN.UK.2015-4.RLTS.T41732A68610784.en . Retrieved 12 November 2021.
  3. Ogilby, J.D. (25 August 1908). "On new genera and species of fishes". Proceedings of the Royal Society of Queensland 21: 126.
  4. 1 2 3 4 5 6 7 8 9 Compagno, L.J.V. (2002). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date (Volume 2). Rome: Food and Agriculture Organization of the United Nations. pp. 142146 ISBN   92-5-104543-7.
  5. 1 2 Froese, Rainer; Pauly, Daniel (eds.) (2010). "Brachaelurus waddi" in FishBase. January 2010 version.
  6. Goto, T. (2001). "Comparative Anatomy, Phylogeny and Cladistic Classification of the Order Orectolobiformes (Chondrichthyes, Elasmobranchii)". Memoirs of the Graduate School of Fisheries Science, Hokkaido University48 (1): 1–101.
  7. 1 2 Murch, A. Blind Shark - Brachaelurus waddi information. Elasmodiver.com. Retrieved 31 January 2010.
  8. 1 2 3 Last, P.R. and J.D. Stevens (2009). Sharks and Rays of Australia (second ed). Harvard University Press. pp. 131. ISBN   0-674-03411-2.
  9. 1 2 3 Michael, S.W. (1993). Reef Sharks & Rays of the World. Sea Challengers. p. 40. ISBN   0-930118-18-9.
  10. 1 2 3 Michael, S.W. "Sharks at Home". Aquarium Fish Magazine March 2004: pp. 2029.
  11. Caira, J.N., K. Jensen and C.J. Healy (1999). "On the phylogenetic relationships among tetraphyllidean, lecanicephalidean and diphyllidean tapeworm genera". Systematic Parasitology42: 77151.