The blind electric ray (''Typhlonarke aysoni'') is a little-known

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of sleeper ray in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Narkidae Members of the family Narkidae are commonly known as sleeper rays. They are restricted to the temperate and tropical Indo-West Pacific from South Africa to Japan to Indonesia, and are exclusively marine and are absent from freshwater habitats. ...

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

. It is found on the bottom, typically at a depth of . Reaching in length, this species has a thin, nearly circular

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

disc without visible eyes, and a short tail with a single

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

. Its

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

s are divided in two, with the anterior portion forming a limb-like appendage; in males the

claspers In biology, a clasper is a male anatomical structure found in some groups of animals, used in mating. Male cartilaginous fish have claspers formed from the posterior portion of their pelvic fin which serve to channel semen into the female's c ...

do not extend past the disc margin. A weak swimmer, the blind electric ray likely pushes itself along using its pelvic fins. It is known to feed on

polychaete worm Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are ma ...

s, and can defend itself with an

electric shock An electrical injury (electric injury) or electrical shock (electric shock) is damage sustained to the skin or internal organs on direct contact with an electric current. The injury depends on the Current density, density of the current, tissu ...

. Reproduction is aplacental viviparous. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

(IUCN) does not have enough information to assess the conservation status of this species.

Taxonomy

The

trawl Trawling is an industrial 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 di ...

er ''Doto'' collected the first known specimen of the blind electric ray from the

Foveaux Strait Foveaux Strait ( ; ) is a strait that separates Stewart Island from the South Island of New Zealand. The width of the strait ranges from about , and the depth varies between . The strait was first charted by an American Seal hunting, sealer, O ...

, during a research cruise in early 1900. The head of the expedition Lake F. Ayson gave the specimen to Augustus Hamilton of the

Dominion Museum The Museum of New Zealand Te Papa Tongarewa is New Zealand's national museum and is located in Wellington. Usually known as Te Papa ( Māori for ' the treasure box'), it opened in 1998 after the merging of the National Museum of New Zealand a ...

, who named it ''Astrape aysoni'' in his honor. Hamilton published his account of the species in a 1902 volume of the

scientific journal In academic publishing, a scientific journal is a periodical publication designed to further the progress of science by disseminating new research findings to the scientific community. These journals serve as a platform for researchers, schola ...

''Transactions and Proceedings of the New Zealand Institute''. In 1909, Edgar R. Waite created the new genus ''Typhlonarke'' for this species. The blind electric ray may also be referred to as the blind legged torpedo or the round electric ray.

Distribution and habitat

The exact range of the blind electric ray is uncertain owing to confusion with the oval electric ray. The two species are found off the eastern coast of New Zealand, from the

East Cape East Cape is the easternmost point of the main islands of New Zealand. It is at the northern end of the Gisborne District of the North Island. East Cape was originally named "Cape East" by British explorer James Cook during his 1769–1779 voy ...

North Island The North Island ( , 'the fish of Māui', historically New Ulster) is one of the two main islands of New Zealand, islands of New Zealand, separated from the larger but less populous South Island by Cook Strait. With an area of , it is the List ...

to the Snares Shelf south of

South Island The South Island ( , 'the waters of Pounamu, Greenstone') is the largest of the three major islands of New Zealand by surface area, the others being the smaller but more populous North Island and Stewart Island. It is bordered to the north by ...

, including the

Cook Cook or The Cook may refer to: Food preparation * Cooking, the preparation of food * Cook (domestic worker), a household staff member who prepares food * Cook (profession), an individual who prepares food for consumption in the food industry * C ...

and Foveaux Straits and the Stewart and

Chatham Islands The Chatham Islands ( ; Moriori language, Moriori: , 'Misty Sun'; ) are an archipelago in the Pacific Ocean about east of New Zealand's South Island, administered as part of New Zealand, and consisting of about 10 islands within an approxima ...

. This

bottom-dwelling The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

species typically occurs at a depth of , but has been reported from between deep.

Description

The blind electric ray has a nearly circular

disc measuring about 70% of the total length, with rather thin margins. The tiny eyes are not visible externally, being located beneath the surface of the skin; their positions are indicated by small white patches. Following the eyes are oval spiracles with raised, smooth rims. The nostrils are closely spaced, with their outer margins curled to form near-complete tubes, and their inner margins enlarged and fused together into a fleshy, skirt-shaped curtain that almost reaches the mouth. The mouth is small and deeply recessed. The teeth are arranged with a

quincunx A quincunx ( ) is a geometry, geometric pattern consisting of five points arranged in a cross, with four of them forming a Square (geometry), square or rectangle and a fifth at its center. The same pattern has other names, including "in saltire" ...

pattern to form narrow plates limited to the front of the jaws. There are 10–12 tooth rows in either jaw; the innermost teeth have a sharp cusp, while the outermost teeth are worn down and flattened. 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 c ...

s are short and curved. The anterior portion of each

is modified into a wide, paddle-like appendage. The posterior portion of the pelvic fins merge smoothly with the pectoral fins to form part of the disc; there is a notch where their margins meet the tail. Adult males have relatively small, slightly flattened

whose tips do not extend past the disc margin. The single

is rectangular in shape with a rounded trailing margin, and originates over the rear of the pelvic fin bases. The short, thick tail bears faint lateral skin folds along either side and terminates in a nearly circular

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

slightly longer than tall. The skin is entirely devoid of

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 scale (zoology), scales, which can also provide effective Underwater camouflage, camouflage through the us ...

s. This species is uniformly brown above, becoming darker towards the tail, and beige below. The undersides of the pelvic fin appendages are nearly white. Most blind electric rays do not exceed in length. However, there is an old report of a specimen that may have been over long.

Biology and ecology

With flabby musculature and a reduced tail, the blind electric ray seems to have very limited swimming capability. Instead, it is inferred to "walk" along the bottom on its mobile pelvic fin appendages. A blind

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

that probably feeds via suction, this species is known to consume

s. Like other electric rays, it has a pair of kidney-shaped

electric organ An electric organ, also known as electronic organ, is an electronic keyboard instrument which was derived from the harmonium, pipe organ and theatre organ. Originally designed to imitate their sound, or orchestral sounds, it has since develop ...

s located beside its head, that allow it to generate an

for defense. Each electric organ is made of 180–200 relatively large, fluid-filled hexagonal columns, which essentially act as batteries connected in parallel. A known

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

of this species is the

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

''Pentaloculum macrocephalum''. The blind electric ray is aplacental viviparous, with females bearing litters of up to 11. The newborns measure long.

Human interactions

The blind electric ray is caught in

bottom trawl Bottom trawling is trawling (towing a trawl, which is a fishing net) along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and Demersal zone, demersal trawling. Benthic tra ...

s and may be threatened by

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 p ...

within its range. However, specific data is lacking and the

(IUCN) has listed it under

Data Deficient A data deficient (DD) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as offering insufficient information for a proper assessment of conservation status to be made. This does not necessaril ...

. In June 2018 the New Zealand Department of Conservation classified the blind electric ray as "Not Threatened" with the qualifier "Data Poor" under the

New Zealand Threat Classification System The New Zealand Threat Classification System is used by the Department of Conservation to assess conservation priorities of species in New Zealand. The system was developed because the IUCN Red List, a similar conservation status system, had s ...

References

{{Taxonbar, from=Q2489603 blind electric ray Endemic marine fish of New Zealand blind electric ray Strongly electric fish