Marbled electric ray

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Marbled electric ray
Torpedo marmorata2.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Batoidea
Order: Torpediniformes
Family: Torpedinidae
Genus: Torpedo
Species:
T. marmorata
Binomial name
Torpedo marmorata
A. Risso, 1810
Torpedo marmorata rangemap.png
Range of the marbled electric ray [1]
Synonyms

Torpedo diversicolorDavy, 1834
Torpedo galvaniRisso, 1810
Torpedo immaculataRafinesque, 1810
Torpedo pictaLowe, 1843
Torpedo punctataRafinesque, 1810
Torpedo trepidansValenciennes, 1843
Torpedo vulgarisFleming, 1828

Contents

The marbled electric ray (Torpedo marmorata) is a species of electric ray in the family Torpedinidae found in the coastal waters of the eastern Atlantic Ocean from the North Sea to South Africa. This benthic fish inhabits rocky reefs, seagrass beds, and sandy and muddy flats in shallow to moderately deep waters. It can survive in environments with very little dissolved oxygen, such as tidal pools. The marbled electric ray has a nearly circular pectoral fin disc and a muscular tail that bears two dorsal fins of nearly equal size and a large caudal fin. It can be identified by the long, finger-like projections on the rims of its spiracles, as well as by its dark brown mottled color pattern, though some individuals are plain-colored. Males and females typically reach 36–38 cm (14–15 in) and 55–61 cm (22–24 in) long respectively.

Nocturnal and solitary, the marbled electric ray can often be found lying the sea floor buried except for its eyes and spiracles. This slow-moving predator feeds almost exclusively on small bony fishes, which it ambushes from the bottom and subdues with strong electric bursts. It defends itself by turning towards the threat, swimming in a loop, or curling up with its underside facing outward, while emitting electric shocks to drive off the prospective predator. Its paired electric organs are capable of producing 70–80 volts of electricity. This species is aplacental viviparous, with the developing embryos sustained by yolk and histotroph ("uterine milk") produced by the mother. Mating takes place from November to January, and females bear litters of 3–32 pups every other year after a gestation period of 9–12 months. The newborn ray is immediately capable of using electricity to hunt.

The electric shock delivered by a marbled electric ray can be severe but is not directly life-threatening. Its electrogenic properties have been known since classical antiquity, when live rays were used to treat conditions such as chronic headaches. This and other electric ray species are used as model organisms in biomedical research. Various coastal demersal fisheries take the marbled electric ray as bycatch; captured rays are usually discarded as they have little commercial value. The impact of fishing on its population is uncertain, and thus International Union for Conservation of Nature (IUCN) has listed this ray as Vulnerable. In the Mediterranean Sea, it remains the most common electric ray and in some areas may be increasing in number.

Taxonomy

Risso's illustration of the marbled electric ray, accompanying his original species description. Torpedo marmorata by risso.png
Risso's illustration of the marbled electric ray, accompanying his original species description.

French naturalist Antoine Risso described the marbled electric ray as Torpedo marmorata in his 1810 Ichtyologie de Nice, ou histoire naturelle des poissons du département des Alpes maritimes (Ichthyology of Nice, or natural history of fishes in the Alpes-Maritimes ). The specific epithet marmorata means "marbled" in Latin, and refers to the ray's color pattern. [2] Because no type specimens are known, in 1999 Ronald Fricke designated Risso's original illustration as the species lectotype. [3]

Within the genus Torpedo, the marbled electric ray belongs to the subgenus Torpedo, which differs from the other subgenus Tetronarce in having fringed margins on their spiracles and generally ornate dorsal coloration. [4] Other common names for this species include common crampfish, marbled torpedo, numbfish, and spotted torpedo. [5]

Distribution and habitat

Sandy flats are one of the habitats occupied by the marbled electric ray. Torpedo marmorata corsica.jpg
Sandy flats are one of the habitats occupied by the marbled electric ray.

Widely distributed in the eastern Atlantic Ocean, the marbled electric ray is found from Scotland and the southern North Sea southward to the Cape of Good Hope,and north at least as far as Durban, likely further. South Africa. In addition it is present in the Mediterranean Sea, with higher densities in western areas. [6] It prefers temperatures cooler than 20 °C (68 °F). [1] [7] This species is typically found at depths of 10–30 m (33–98 ft) off Britain and Ireland, [8] 20–100 m (66–328 ft) off Italy, and down to 200 m (660 ft) off Tunisia. [9] It has been recorded from as deep as 370 m (1,210 ft). [5] The marbled electric ray tends to be found deeper than the common torpedo (T. torpedo), which shares the southern portion of its range. [9]

Bottom-dwelling in nature, the marbled electric ray inhabits rocky reefs and seagrass beds, as well as nearby areas with sandy or muddy bottoms. [7] During warm summer months, pregnant females are known to migrate into Arcachon Bay in northwestern France, where they are commonly found in very shallow, muddy pools near oyster beds. [10] [11] This species may conduct a northward migration in summer and autumn, into the waters of the British Isles. [8]

Description

The marbled electric ray can be identified by its ornate color pattern and fringed spiracles. Torpedo marmorata portugal.jpg
The marbled electric ray can be identified by its ornate color pattern and fringed spiracles.

The body of the marbled electric ray is soft and flabby, and entirely lacks dermal denticles. The thick pectoral fin disc is nearly circular and comprises about 59–67% of the total length; the paired kidney-shaped electric organs are visible beneath the skin, outside of the small eyes. Immediately posterior to each eye is a large, oval spiracle, which bears 6–8 long, finger-like projections on the rim that almost meet at the center. On the "nape" behind the spiracles, there are 5–7 prominent mucous pores. Between the nostrils, there is a quadrangular curtain of skin much broader than long, that almost reaches the small, arched mouth. The teeth are small with a single pointed cusp, and are arranged with a quincunx pattern into a pavement-like band in either jaw. The five pairs of gill slits are small and located beneath the disc. [5] [12] [13]

The two dorsal fins have rounded apexes and are placed close together; the base of each fin measures about two-thirds its height. The rear of the first dorsal fin base is located behind the rear of the pelvic fin bases. The second dorsal fin is only slightly smaller than the first. [5] [12] The short, robust tail has skin folds running along either side, and terminates in a large caudal fin shaped like a triangle with blunt corners. [7] [13] The upper surface has a dark mottled pattern on a light to dark brown background; some individuals are uniformly brown. [12] The underside is plain off-white with darker fin margins. [14] This species can grow up to 1 m (3.3 ft) long, [5] though few exceed 36–38 cm (14–15 in) long for males and 55–61 cm (22–24 in) long for females. The much larger sizes attained by females can be attributed to the resource investment needed for reproduction. There seems to be little geographic variation in maximum size. [15] [16] The maximum weight on record is 3 kg (6.6 lb). [5]

Biology and ecology

The marbled electric ray can survive in environments with very little oxygen, such as tidal pools. Torpedo marmorata 089 nevit.jpg
The marbled electric ray can survive in environments with very little oxygen, such as tidal pools.

Solitary and slow-moving, [14] the marbled electric ray may remain motionless for several days at a time. [10] It is more active at night and spends much of the day buried in sediment with only the eyes and spiracles showing. [1] Consistent with its sluggish nature, the marbled electric ray has a low blood oxygen carrying capacity and heart rate (10–15 beats/min), and consumes less oxygen than other sharks and rays of similar size. [10] It is highly tolerant of being deprived of oxygen (hypoxia), allowing it to cope with deoxygenated bottom waters or being stranded in small pools by the falling tide. The ray stops breathing entirely when the oxygen partial pressure in the water drops below 10–15 Torr, and can survive such a state for at least five hours. It deals with extreme hypoxia by coupling anaerobic glycolysis to additional energy-producing pathways in its mitochondria, which serves to slow down the accumulation of potentially harmful lactate within its cells. [17]

Like other members of its family, the marbled electric ray can produce a strong electric shock for attack and defense, produced by a pair of electric organs derived from muscle tissue. Each electric organ consists of 400–600 vertical columns, with each column composed of a stack of roughly 400 jelly-filled "electroplates" that essentially act like a battery. [11] This ray has been measured producing up to 70–80 volts, and the maximum potential of the electric discharge has been estimated to be as high as 200 volts. The strength of the electric shock declines progressively as the ray becomes fatigued. [13] Experiments in vitro have found that the nerves innervating the electric organ essentially stop functioning at temperatures below 15 °C (59 °F). As the water temperature in the wild regularly drops below this threshold in winter, it is possible that the ray does not use its electric organ for part of the year. Alternately, the ray may have a yet-unknown physiological mechanism to adapt electric organ function to the cold. [18]

Known parasites of the marbled electric ray include the tapeworms Anthocephalum gracile [19] and Calyptrobothrium riggii, [20] the leeches Pontobdella muricata and Trachelobdella lubrica, [21] the monogeneans Amphibdella torpedinis, [22] Amphibdelloides kechemiraen, [23] A. maccallumi, [22] A. vallei, [23] Empruthotrema raiae, E. torpedinis, [24] and Squalonchocotyle torpedinis, [25] and the nematodes Ascaris torpedinis and Mawsonascaris pastinacae. [7]

Feeding

Leaping mullet are an important prey of the marbled electric ray. Meerasche.jpg
Leaping mullet are an important prey of the marbled electric ray.

The marbled electric ray is an ambush predator that employs electricity to capture prey. Vision is of little importance in hunting, as the ray's eyes are often obscured as it lies buried on the bottom. Instead, it likely relies on the mechanoreceptors of its lateral line, as it only attacks moving prey. The electroreceptive ampullae of Lorenzini may also contribute to prey detection. [26]

Small, benthic bony fishes constitute over 90% of the marbled electric ray's diet by weight; [27] these include gobies, hake, sea bass, mullets, jack mackerel, sea breams, goatfish, damselfish, wrasses, conger eels, and flatfish. [5] [9] [12] Cephalopods such as European squid (Loligo vulgaris) and elegant cuttlefish (Sepia elegans) are a minor secondary food source. There is a single record of an individual that had swallowed a penaeid prawn, Penaeus kerathurus , [27] and a study of captive rays found that they reject live Macropodia crabs. [28] Off southern France, by far the most important prey species is the leaping mullet (Liza saliens). [27] Food items are swallowed whole; there is a record of a ray 41 cm (16 in) long that had consumed a three-bearded rockling (Gaidropsarus vulgaris) 34 cm (13 in) long. [12]

Two distinct types of prey capture behavior have been observed in the marbled electric ray. The first is "jumping", used by the ray to attack prey fish that swim close to its head, typically no farther than 4 cm (1.6 in). In the "jump", the ray pulls back its head and then thrusts its disc upwards, reaching about two or three times as high as the prey fish is from the bottom. Simultaneously, it makes a single tail stroke and produces a high-frequency (230–430 Hz, increasing with temperature) burst of electricity. The initial electric burst is very short, containing only 10–64 pulses, but is still strong enough to cause tetanic contraction in the body of the prey fish, often breaking its vertebral column. As the ray glides forward, the motion of the jump sweeps the now-paralyzed prey beneath it, whereupon it is enveloped by the disc and maneuvered to the mouth. Electric bursts continues to be produced during this process; the total number of electric pulses over a single jump increases with size, ranging from 66 in a newborn 12 cm (4.7 in) long to 340 in an adult 45 cm (18 in) long. The jump lasts no more than two seconds. [26] [28]

The second type of prey capture behavior is "creeping", used by the ray for stationary or slow-moving prey; this includes stunned prey that may have drifted out of reach from a jumping attack. In creeping, the ray makes small up and down motions of its disc coupled with small beats of its tail. The raising of the disc draws water beneath it and pulls the prey towards the ray, while the lowering of the disc and the tail beats move the ray towards the prey in small increments. When it reaches the prey, the ray opens its mouth to suck it in. Short electric bursts are produced as necessary, depending on the movement of the prey, and continue through ingestion. [28]

Defense

When threatened, the marbled electric ray adopts a defensive posture that facilitates the delivery of electric shocks. Torpedo marmorata corsica2.jpg
When threatened, the marbled electric ray adopts a defensive posture that facilitates the delivery of electric shocks.

Because of its size and electrical defenses, the marbled electric ray does not often fall prey to other animals such as sharks. [7] This species exhibits different defensive behaviors depending on whether a prospective predator grasps it by the disc or the tail. A ray touched on the disc will quickly turn toward the threat while producing electric shocks; this is followed by it fleeing in a straight line, after which it may re-bury itself. A ray touched on the tail will propel itself upward into a loop; if it has not escaped after the maneuver, the ray will curl into a ring with the belly facing outward, so as to present the area of its body with the highest electric field gradient (the underside of the electric organs) towards the threat; these behaviors are accompanied by short, strong electric shocks. The ray tends to produce more electric bursts when protecting its tail than when protecting its disc. [28]

Life history

The marbled electric ray exhibits aplacental viviparity, in which the developing embryos are nourished initially by yolk, which is later supplemented by nutrient-rich histotroph ("uterine milk") produced by the mother. Adult females have two functional ovaries and uteruses; the inner lining of the uterus bears a series of parallel lengthwise folds. [29] The reproductive cycle for females is probably biennial, while males are capable of mating every year. Mating occurs from November to January, and the young are born the following year after a gestation period of 9–12 months. [15] [16] The litter size ranges from 3 to 32, increasing with the size of the female. [12] [16]

The electric organs first appear when the embryo is 1.9–2.3 cm (0.75–0.91 in) long, at which time it has distinct eyes, pectoral and pelvic fins, and external gills. At an embryonic length of 2.0–2.7 mm (0.079–0.106 in), the gill clefts close dorsally, leaving the gill slits beneath the disc as in all rays. At the same time, the four blocks of primordial cells that make up each electric organ rapidly coalesce together. The embryo's pectoral fins enlarge and fuse with the snout at a length of 2.8–3.7 cm (1.1–1.5 in), giving it the typical circular electric ray shape. When the embryo is 3.5–5.5 cm (1.4–2.2 in) long, the external gills are resorbed and pigmentation develops. The embryo can produce electric discharges by a length of 6.6–7.3 cm (2.6–2.9 in). The strength of the discharge increases by a magnitude of 105 over the course of gestation, reaching 47–55 volts by an embryonic length of 8.6–13 cm (3.4–5.1 in), close to that of an adult. [11]

Newborns measure approximately 10–14 cm (3.9–5.5 in) long, [1] and are immediately capable of performing characteristic predatory and defensive behaviors. [11] Males mature sexually at approximately 21–29 cm (8.3–11.4 in) long and five years of age, while females mature significantly larger and older at 31–39 cm (12–15 in) long and twelve years of age. The maximum lifespan is 12–13 years for males and around 20 years for females. [1]

Human interactions

The shock delivered by the marbled electric ray can be painful but is seldom life-threatening, although there is a danger of a shocked diver becoming disoriented underwater. [7] Its electrogenic properties have been known since classical antiquity, leading it and other electric fishes to be used in medicine. The ancient Greeks and Romans applied live rays to those afflicted with conditions such as chronic headaches and gout, and recommended that its meat be eaten by epileptics. [14] [30]

The marbled electric ray is caught incidentally in bottom trawls, trammel nets, and bottom longlines; it has little economic value and is mostly discarded at sea when captured. The International Union for Conservation of Nature (IUCN) assesses it as Vulnerable. At least in the northern Mediterranean, surveys have found that it remains the most common electric ray, and is perhaps becoming more abundant in Italian waters. [1] This and other electric ray species are used as model organisms in biomedical research because their electric organs are rich in acetylcholine receptors, which play an important role in the human nervous system. [31]

Related Research Articles

<span class="mw-page-title-main">Electric ray</span> Order of cartilaginous fishes

The electric rays are a group of rays, flattened cartilaginous fish with enlarged pectoral fins, composing the order Torpediniformes. They are known for being capable of producing an electric discharge, ranging from 8 to 220 volts, depending on species, used to stun prey and for defense. There are 69 species in four families.

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

The family Torpedinidae contains 22 species of electric rays or torpedoes, flat cartilaginous fishes that produce electricity as a defense and feeding mechanism. They are slow-moving bottom-dwellers.

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

Tetronarce californica also known as the Pacific electric ray is a species of electric ray in the family Torpedinidae, endemic to the coastal waters of the northeastern Pacific Ocean from Baja California to British Columbia. It generally inhabits sandy flats, rocky reefs, and kelp forests from the surface to a depth of 200 m (660 ft), but has also been known to make forays into the open ocean. Measuring up to 1.4 m (4.6 ft) long, this species has smooth-rimmed spiracles and a dark gray, slate, or brown dorsal coloration, sometimes with dark spots. Its body form is typical of the genus, with a rounded pectoral fin disc wider than long and a thick tail bearing two dorsal fins of unequal size and a well-developed caudal fin.

<i>Torpedo</i> (genus) Genus of cartilaginous fishes

Torpedo is a genus of rays, commonly known as electric rays, torpedo rays, or torpedoes. They are slow-moving bottom-dwellers capable of generating electricity as a defense and feeding mechanism.

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

The pelagic stingray is a species of stingray in the family Dasyatidae, and the sole member of its genus. It is characterized by the wedge-like shape of its pectoral fin disc, which is much wider than long, as well as by the pointed teeth in both sexes, whip-like tail with extremely long tail spine, and uniform violet to blue-green coloration. It generally reaches 59 cm (23 in) in width. The pelagic stingray has a worldwide distribution in waters warmer than 19 °C (66 °F), and migrates seasonally to spend the summer closer to the continental shelf and at higher latitudes. The only stingray that almost exclusively inhabits the open ocean, this species is typically found in surface waters down to a depth of 100 m (330 ft). As a consequence of its midwater habits, its swimming style has evolved to feature more of a flapping motion of the pectoral fins, as opposed to the disc margin undulations used by other, bottom-dwelling stingrays.

<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.

The Aden Gulf torpedo or Aden torpedo is a poorly known species of electric ray in the family Torpedinidae, seemingly endemic to the eastern Gulf of Aden, near the coast of Yemen. Growing to 41 cm (16 in) long, this species has a nearly circular pectoral fin disc and a short, thick tail with two dorsal fins and a well-developed caudal fin. It is characterized by its reddish dorsal coloration, which in contrast to related species lacks any additional markings. The International Union for Conservation of Nature (IUCN) has assessed the Aden Gulf torpedo as Endangered, citing its extremely small range and the intensive shrimp trawling that occurs in the region.

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

The Florida torpedo is a rare and little-known species of electric ray in the family Torpedinidae. It is known only from two specimens and a some wild sightings. Torpedoes have been recorded from three scattered locations in the Florida Straits and the western Caribbean Sea, and appear to inhabit coral habitats.

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

The black-spotted torpedo is a poorly known, uncommon species of electric ray in the family Torpedinidae, known for being capable of generating an electric shock. It is endemic to southern Africa and possibly several small Indian Ocean islands, although the latter reports may represent undescribed new species. Its appearance is similar to the Gulf torpedo, but it is duller in coloration.

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

The Gulf torpedo or variable electric ray, is a species of electric ray in the family Torpedinidae. It is found in the Indian Ocean, but may represent a species flock of several local endemic species. It is distinguishable from other Torpedo species in its range by its ornate dorsal coloration. Another common name, marbled electric ray, is not to be confused with Torpedo marmorata.

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).

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

The finless sleeper ray is a species of electric ray in the family Narkidae, and the sole member of its genus. It is found over the continental shelf of Southeast Asia from the eastern Andaman Sea to Vietnam and Borneo. Typically growing no more than 15 cm (5.9 in) long, it may be the smallest cartilaginous fish. The finless sleeper ray is the only electric ray that lacks dorsal fins. It has an oval pectoral fin disc that varies from longer than wide to wider than long, depending on age, and a short, robust tail that terminates in a short, deep caudal fin. The trailing margins of its pelvic fins are sexually dimorphic, being more concave in males.

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

The common torpedo, also known as ocellate torpedo or eyed electric ray, is a species of electric ray in the family Torpedinidae. It is found in the Mediterranean Sea and the eastern Atlantic Ocean from the Bay of Biscay to Angola, and is a benthic fish typically encountered over soft substrates in fairly shallow, coastal waters. Growing to 60 cm (24 in) long, this species has a nearly circular pectoral fin disc and a short, thick tail with two dorsal fins of nearly equal size and a large caudal fin. It can be identified by the prominent blue spots on its back, which usually number five but may vary from zero to nine, as well as by the small knobs on the rims of its spiracles.

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

The spiny butterfly ray or giant butterfly ray is a species of butterfly ray, family Gymnuridae, native to the shallow coastal waters of the Atlantic Ocean. A large ray that can measure over 2 m across, it may be distinguished from the sympatric smooth butterfly ray by the spine at the base of its tail and by a small tentacular structure on the margin of each spiracle. Slow-reproducing and valued for its meat, in recent decades its population has experienced a decline of over 30%, and it has become Critically Endangered in certain parts of its range.

<span class="mw-page-title-main">Reticulate whipray</span> Species of fish

The reticulate whipray or honeycomb stingray is a species of stingray in the family Dasyatidae. It inhabits coastal waters in the western Indian Ocean including the Red Sea, Natal and the Arabian Sea; also a Lessepsian transmigrant in the eastern Mediterranean. A large species reaching 2 m (6.6 ft) in width, the reticulate whipray has a diamond-shaped pectoral fin disc and an extremely long tail without fin folds. Both its common and scientific names refer to its ornate dorsal color pattern of many small, close-set dark spots or reticulations on a lighter background. However, the reticulate whipray is only one of several large spotted stingrays in the Indo-Pacific which, coupled with the variability of its coloration with age and locality, has resulted in a great deal of taxonomic confusion.

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

The Atlantic torpedo is a species of electric ray in the family Torpedinidae. It is found in the Atlantic Ocean, from Nova Scotia to Brazil in the west and from Scotland to West Africa and off southern Africa in the east, occurring at depths of up to 800 m (2,600 ft), and in the Mediterranean Sea. Younger individuals generally inhabit shallower, sandy or muddy habitats, whereas adults are more pelagic in nature and frequent open water. Up to 1.8 m (6 ft) long and weighing 90 kg (200 lb), the Atlantic torpedo is the largest known electric ray. Like other members of its genus, it has an almost circular pectoral fin disk with a nearly straight leading margin, and a robust tail with a large triangular caudal fin. Distinctive characteristics include its uniform dark color, smooth-rimmed spiracles, and two dorsal fins of unequal size.

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

The Japanese sleeper ray is a species of electric ray in the family Narkidae. It is common in the inshore and offshore waters of the northwestern Pacific Ocean from southern Japan to southern China. Growing up to 40 cm (16 in) long, the Japanese sleeper ray has a nearly circular pectoral fin disc colored reddish to chocolate brown above, sometimes with darker or lighter spots, and lighter brown below. The spiracles behind its small eyes have raised, smooth rims. Its short and muscular tail bears a single dorsal fin positioned aft of the rounded pelvic fins, and terminates in a large caudal fin.

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

The onefin electric ray or Cape numbfish is a common but little-known species of electric ray in the family Narkidae, native to South Africa and Namibia. It is a benthic fish found in shallow coastal bays over sandy or muddy bottoms. This small species reaches 38 cm (15 in) in length, and has a nearly circular pectoral fin disc and a short, muscular tail that supports a large caudal fin. It can be identified by its single dorsal fin, which is located over the large pelvic fins. Its dorsal coloration is yellowish to dusky brown.

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

The Tasmanian numbfish is a species of electric ray in the family Narcinidae. Endemic to southeastern Australia, this common ray inhabits shallow continental shelf waters in the southern portion of its range and deeper continental slope waters in the northern portion of its range. It prefers sand and mud habitats. This species can be identified by its spade-shaped pectoral fin disc with concave anterior margins, long tail with well-developed skin folds along either side, and plain dark brown dorsal colouration. Its maximum known length is 47 cm (19 in).

<i>Pontobdella muricata</i> Species of annelid (marine leech)

Pontobdella muricata is a species of marine leech in the family Piscicolidae. It is a parasite of fishes and is native to the northeastern Atlantic Ocean, the Baltic Sea, the North Sea, and the Mediterranean Sea.

References

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  11. 1 2 3 4 Mellinger, J.; Belbenoit, P.; Ravaille, M.; Szabo, T. (1978). "Electric organ development in Torpedo marmorata, Chondrichthyes". Developmental Biology. 67 (1): 167–188. doi:10.1016/0012-1606(78)90307-X. PMID   720752.
  12. 1 2 3 4 5 6 Michael, S.W. (1993). Reef Sharks & Rays of the World. Sea Challengers. p. 77. ISBN   0-930118-18-9.
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  15. 1 2 Abdel-Aziz, S.H. (1994). "Observations on the biology of the common torpedo (Torpedo torpedo, Linnaeus, 1758) and marbled electric ray (Torpedo marmorata, Risso, 1810) from Egyptian Mediterranean waters". Australian Journal of Marine and Freshwater Research. 45 (4): 693–704. doi:10.1071/MF9940693.
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  17. ↑ Hughes, G.M.; Johnston, I.A. (1978). "Some responses of the electric ray (Torpedo marmorata) to low ambient oxygen tensions" (PDF). Journal of Experimental Biology. 73: 107–117. doi:10.1242/jeb.73.1.107. PMID   25940. Archived from the original (PDF) on 2012-10-07.
  18. ↑ Radii-Weiss, T; Kovacevic, N. (1970). "Influence of low temperature on the discharge mechanism of the electric fish Torpedo marmorata and T. ocellata". Marine Biology. 5 (1): 18–21. Bibcode:1970MarBi...5...18R. doi:10.1007/bf00352488. S2CID   84215332.
  19. ↑ Ruhnke, T.R. (November 1994). "Resurrection of Anthocephalum Linton, 1890 (Cestoda: Tetraphyllidea) and taxonomic information on five proposed members". Systematic Parasitology. 29 (3): 159–176. doi:10.1007/bf00009673. S2CID   45969813.
  20. ↑ Tazerouti, F.; Euzet, L.; Kechemir-Issad, N. (July 2007). "Redescription of three species of Calyptrobothrium Monticelli, 1893 (Tetraphyllidea: Phyllobothriidae), parasites of Torpedo marmorata and T. nobiliana (Elasmobranchii: Torpedinidae). Comments on their parasitic specificity and taxonomic position of species formerly attributed to C. riggii Monticelli, 1893". Systematic Parasitology. 67 (3): 175–185. doi:10.1007/s11230-006-9088-9. PMID   17516135. S2CID   36105477.
  21. ↑ Saglam, N.; Oguz, M.C.; Celik, E.S.; Doyuk, S.A.; Usta, A. (2003). "Pontobdella muricata and Trachelobdella lubrica (Hirudinea: Piscicolidae) on some marine fish in the Dardanelles, Turkey" (PDF). Journal of the Marine Biological Association of the United Kingdom. 83 (6): 1315–1316. Bibcode:2003JMBUK..83.1315S. doi:10.1017/s0025315403008749. S2CID   86234515. Archived from the original (PDF) on 2012-03-23.
  22. 1 2 Llewellyn, J. (1960). "Amphibdellid (monogenean) parasites of electric rays (Torpedinidae)". Journal of the Marine Biological Association of the United Kingdom. 39 (3): 561–589. Bibcode:1960JMBUK..39..561L. doi:10.1017/S0025315400013552. S2CID   53601268.
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  24. ↑ Kearn, G.C. (1976). "Observations on monogenean parasites from the nasal fossae of European rays: Empruthotrema raiae (Maccallum, 1916) Johnston and Tiegs, 1922 and E. torpedinis sp.nov. from Torpedo marmorata". Proceedings of the Institute of Biology and Pedology, Vladivostok, U.S.S.R. 34 (137): 45–54.
  25. ↑ Sproston, N.G. (1946). "A synopsis of the monogenetic trematodes". Transactions of the Zoological Society of London. 25 (4): 185–600. doi:10.1111/j.1096-3642.1946.tb00218.x. S2CID   83754688.
  26. 1 2 Belbenoit, P.; Bauer, R. (1972). "Video recordings of prey capture behaviour and associated electric organ discharge of Torpedo marmorata (Chondrichthyes)". Marine Biology. 17 (2): 93–99. Bibcode:1972MarBi..17...93B. doi:10.1007/BF00347299. S2CID   83314839.
  27. 1 2 3 Capape, C.; Crouzet, S.; Clement, C.; Vergne, Y.; Guelorget, O. (2007). "Diet of the marbled electric ray Torpedo marmorata (Chondrichthyes: Torpedinidae) of the Languedocian coast (south of France, northern Mediterranean)" (PDF). Annales Series Historia Naturalis. 17 (1): 17–22.[ permanent dead link ]
  28. 1 2 3 4 Belbenoit, P. (1986). "Fine analysis of predatory and defensive motor events in Torpedo marmorata (Pisces)". Journal of Experimental Biology. 121: 197–226. doi: 10.1242/jeb.121.1.197 .
  29. ↑ Davy, J. (1834). "Observations on the Torpedo, with an Account of Some Additional Experiments on Its Electricity". Philosophical Transactions of the Royal Society of London. 124: 531–550. doi: 10.1098/rstl.1834.0026 . JSTOR   108075. S2CID   109091189.
  30. ↑ Yarrell, W. (1841). A History of British Fishes: Illustrated by 500 Wood Engravings (second ed.). John Van Voorst, Paternoster Row. p. 545.
  31. ↑ Sheridan, M.N. (1965). "The fine structure of the electric organ of Torpedo marmorata" (PDF). Journal of Cell Biology. 24 (1): 129–141. doi:10.1083/jcb.24.1.129. PMC   2106563 . PMID   14286287.

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