27-418: See text The electric rays are a group of rays , flattened cartilaginous fish with enlarged pectoral fins , composing the order Torpediniformes / t ɔːr ˈ p ɛ d ɪ n ɪ f ɔːr m iː z / . 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. Perhaps
54-804: A 2011 study significantly reevaluated the phylogeny of batoids, using nuclear and mitochondrial DNA from 37 taxa , representing almost all recognized families and all of the traditional four major lineages. This is a far more numerous and diverse set of sample taxa than in any previous study, producing findings reflected in the cladogram below. Holocephali (incl. Chimaera ) [REDACTED] Selachimorpha (Sharks) [REDACTED] Rajiformes (Skates) [REDACTED] Platyrhinidae (Thornbacks) Torpediniformes (Electric rays) [REDACTED] "Guitarfishes 1" ( Trygonorrhinidae ) [REDACTED] "Guitarfishes 2" (incl. Pristidae (Sawfishes)) [REDACTED] Zanobatidae (Panrays) Myliobatoidei (Stingrays) [REDACTED] This study strongly confirmed
81-456: A 2021 study in Nature , the number of oceanic sharks and rays has declined globally by 71% over the preceding 50 years, jeopardising "the health of entire ocean ecosystems as well as food security for some of the world's poorest countries". Overfishing has increased the global extinction risk of these species to the point where three-quarters are now threatened with extinction. This is notably
108-589: A family, the Narkidae. The torpedinids feed on large prey, which are stunned using their electric organs and swallowed whole, while the narcinids specialize on small prey on or in the bottom substrate. Both groups use electricity for defense, but it is unclear whether the narcinids use electricity in feeding. Eschmeyer's Catalog of Fishes lists classifies the following families in the Torpediniformes: Batoid Batomorphi
135-399: A few species, like manta rays , live in the open sea, and only a few live in freshwater, while some batoids can live in brackish bays and estuaries. Most batoids have developed heavy, rounded teeth for crushing the shells of bottom-dwelling species such as snails , clams , oysters , crustaceans , and some fish , depending on the species. Manta rays feed on plankton . Batoids belong to
162-451: A manner similar to the way the torpedo fish stuns with electricity. Scribonius Largus , a Roman physician, recorded the use of torpedo fish for treatment of headaches and gout in his Compositiones Medicae of 46 AD. In the 1770s the electric organs of the torpedo ray were the subject of Royal Society papers by John Walsh , and John Hunter . These appear to have influenced the thinking of Luigi Galvani and Alessandro Volta –
189-616: A parallel circuit, whereas freshwater batteries are arranged in series. This allows freshwater rays to transmit discharges of higher voltage, as freshwater cannot conduct electricity as well as saltwater. With such a battery, an electric ray may electrocute larger prey with a voltage of between 8 volts in some narcinids to 220 volts in Torpedo nobiliana , the Atlantic torpedo. The 60 or so species of electric rays are grouped into 12 genera and two families. The Narkinae are sometimes elevated to
216-403: A ventrally located mouth and can considerably protrude their upper jaw (palatoquadrate cartilage) away from the cranium to capture prey. The jaws have euhyostylic type suspension, which relies completely on the hyomandibular cartilages for support. Bottom-dwelling batoids breathe by taking water in through the spiracles, rather than through the mouth as most fish do, and passing it outward through
243-726: A well-developed caudal fin . The body is thick and flabby, with soft loose skin with no dermal denticles or thorns. A pair of kidney -shaped electric organs are at the base of the pectoral fins. The snout is broad, large in the Narcinidae, but reduced in all other families. The mouth, nostrils , and five pairs of gill slits are underneath the disc. Electric rays are found from shallow coastal waters down to at least 1,000 m (3,300 ft) deep. They are sluggish and slow-moving, propelling themselves with their tails, not by using their pectoral fins as other rays do. They feed on invertebrates and small fish. They lie in wait for prey below
270-405: A womb but without involvement of a placenta. The eggs of oviparous skates are laid in leathery egg cases that are commonly known as mermaid's purses and which often wash up empty on beaches in areas where skates are common. Capture-induced premature birth and abortion (collectively called capture-induced parturition) occurs frequently in sharks and rays when fished. Capture-induced parturition
297-535: Is a clade of cartilaginous fishes , commonly known as rays , this taxon is also known as the superorder Batoidea , but the 5th edition of Fishes of the World classifies it as the division Batomorphi. They and their close relatives, the sharks , compose the subclass Elasmobranchii . Rays are the largest group of cartilaginous fishes, with well over 600 species in 26 families. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to
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#1732783072780324-489: Is rarely considered in fisheries management despite being shown to occur in at least 12% of live bearing sharks and rays (88 species to date). Most species live on the sea floor, in a variety of geographical regions – mainly in coastal waters, although some live in deep waters to at least 3,000 metres (9,800 ft). Most batoids have a cosmopolitan distribution , preferring tropical and subtropical marine environments, although there are temperate and cold-water species. Only
351-537: The Jurassic . The oldest confirmed ray is Antiquaobatis , from the Pliensbachian of Germany . The clade is represented today by sharks , sawfish , rays and skates . Molecular evidence refutes the hypothesis that skates and rays are derived sharks. The monophyly of the skates , the stingrays , and the electric rays has long been generally accepted. Along with Rhinopristiformes , these comprise
378-569: The Trygonorrhinidae , while the latter contains the remainder of Rhinopristiformes (the families Glaucostegidae , Pristidae , Rhinidae , and Rhinobatidae ). In addition, while traditional phylogenies often find electric rays to be the basalmost batoids, followed by the Rhinopristiformes, this analysis finds a polytomy between skates, electric rays, and thornbacks at the base of Batoidea, with weak support for skates being
405-472: The actual most basal lineage, followed by a clade uniting the electric rays and thornbacks. The Mesozoic Sclerorhynchoidea are basal or incertae sedis ; they show features of the Rajiformes but have snouts resembling those of sawfishes. However, evidence indicates they are probably the sister group to sawfishes. Eschmeyer's Catalog of Fishes classigies the rays as follows: According to
432-595: The ancient lineage of cartilaginous fishes. Fossil denticles (tooth-like scales in the skin) resembling those of today's chondrichthyans date at least as far back as the Ordovician , with the oldest unambiguous fossils of cartilaginous fish dating from the middle Devonian . A clade within this diverse family, the Neoselachii , emerged by the Triassic , with the best-understood neoselachian fossils dating from
459-475: The best known members are those of the genus Torpedo . The torpedo undersea weapon is named after it. The name comes from the Latin torpere , 'to be stiffened or paralyzed', from the effect on someone who touches the fish. Electric rays have a rounded pectoral disc with two moderately large rounded-angular (not pointed or hooked) dorsal fins (reduced in some Narcinidae ), and a stout muscular tail with
486-709: The case in the Mediterranean Sea - most impacted by unregulated fishing - where a recent international survey of the Mediterranean Science Commission concluded that only 38 species of rays and skates still subsisted. All sharks and rays are cartilaginous fish, contrasting with bony fishes . Many rays are adapted for feeding on the bottom. Guitarfishes are somewhat between sharks and rays, displaying characteristics of both (though they are classified as rays). Torpedo nobiliana Too Many Requests If you report this error to
513-408: The founders of electrophysiology and electrochemistry. Henry Cavendish proposed that electric rays use electricity; he built an artificial ray consisting of fish shaped Leyden jars to successfully mimic their behaviour in 1773. The torpedo fish, or electric ray, appears continuously in premodern natural histories as a magical creature, and its ability to numb fishermen without seeming to touch them
540-666: The four traditionally accepted major batoid lineages, as in Nelson's 2006 Fishes of the World . However, the exact phylogeny of the major batoid lineages, internally and with respect to one another, has been subject to diverse treatments. The following cladogram is based on a comprehensive morphological assessment of batoid phylogeny published in 2004: Holocephali (incl. Chimaera ) [REDACTED] Selachimorpha (Sharks) [REDACTED] Torpediniformes [REDACTED] Rhinopristiformes [REDACTED] Rajiformes [REDACTED] Myliobatiformes [REDACTED] However,
567-507: The gills. Batoids reproduce in a number of ways. As is characteristic of elasmobranchs, batoids undergo internal fertilization . Internal fertilization is advantageous to batoids as it conserves sperm, does not expose eggs to consumption by predators, and ensures that all the energy involved in reproduction is retained and not lost to the environment. All skates and some rays are oviparous (egg laying) while other rays are ovoviviparous , meaning that they give birth to young which develop in
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#1732783072780594-471: The head, and gill slits that are placed on their ventral surfaces. Batoids are flat-bodied, and, like sharks, are cartilaginous fish, meaning they have a boneless skeleton made of a tough, elastic cartilage. Most batoids have five ventral slot-like body openings called gill slits that lead from the gills , but the Hexatrygonidae have six. Batoid gill slits lie under the pectoral fins on
621-437: The lower to the upper surface of the body. The nerves that signal the organ to discharge branch repeatedly, then attach to the lower side of each plaque in the batteries. These are composed of hexagonal columns, closely packed in a honeycomb formation. Each column consists of 500 to more than 1000 plaques of modified striated muscle, adapted from the branchial (gill arch) muscles. In marine fish , these batteries are connected as
648-413: The sand or other substrate, using their electricity to stun and capture it. The electrogenic properties of electric rays have been known since antiquity, although their nature was not understood. The ancient Greeks used electric rays to numb the pain of childbirth and operations. In his dialogue Meno , Plato has the character Meno accuse Socrates of "stunning" people with his puzzling questions, in
675-419: The traditionally accepted internal monophyly of skates, stingrays, and electric rays. It also recovered panrays as sister to the stingrays, as older morphological analyses had suggested. However, it found the Rhinopristiformes, including the sawfishes and various "guitarfishes", to be paraphyletic , comprising two distinct clades. Referred to as "Guitarfishes 1" and "Guitarfishes 2", the former contains only
702-401: The underside, whereas a shark's are on the sides of the head. Most batoids have a flat, disk-like body, with the exception of the guitarfishes and sawfishes , while most sharks have a spindle-shaped body. Many species of batoid have developed their pectoral fins into broad flat wing-like appendages. The anal fin is absent. The eyes and spiracles are located on top of the head. Batoids have
729-422: Was a significant source of evidence for the belief in occult qualities in nature during the ages before the discovery of electricity as an explanatory mode. The electric rays have specialised electric organs . Many species of rays and skates outside the family have electric organs in the tail; however, the electric ray has two large kidney-shaped electric organs on each side of its head, where current passes from
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