| Torpedo | |
|---|---|
 | |
| Torpedo torpedo | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Order: | Torpediniformes |
| Family: | Torpedinidae |
| Genus: | Torpedo Forsskål, 1775[2] |
| Type species | |
| Torpedo torpedo | |
Torpedo is agenus ofrays, commonly known aselectric rays,torpedo rays, ortorpedoes. They are slow-movingbottom-dwellers capable of generatingelectricity as a defense and feeding mechanism.
Thenavalweapon known as thetorpedo was named after this genus, whose own name is derived from theLatin wordtorpidus meaning 'numb' or 'paralysed',[3] presumably the sensation one would feel after experiencing the ray's electric shock.
Peter Forsskål validly published the genus nameTorpedo in 1775, predating the use of the genus nameTorpedo byDuméril in 1806, meaning thatTorpedo Duméril, 1806 (often cited in catalogs) is a junior homonym of Forsskål's name and cannot be used.[2] Forsskål included only a single species,Raja torpedo Linnaeus, 1758, thereby making it the type species of the genus. While Forsskål's description indicated that he had misinterpreted Linnaeus' name and ascribed it to another electric fish (currently known asMalapterurus electricus), this potential source of confusion was rectified in 2008, whenRaja torpedo Linnaeus was officially made the type species underICZN Article 70.3.1.[2]
Torpedo rays are flat like other rays, disc-shaped, withcaudal fins that vary in length. Their mouths andgill slits are located on their undersides. Males haveclaspers near the base of the tail. Females areovoviviparous, meaning they form eggs but do not lay them. The young "hatch" within her body and she bears them live.[1]
The largestspecies is theGulf torpedo,Torpedo sinuspersici, which can grow to a weight of 13 kg (29 lb). Electric rays have patches of modifiedmuscle cells calledelectroplaques that make up anelectric organ. These generate an electric gradient, similar to the normalelectric potential across mostcell membranes, but amplified greatly by its concentration into a very small area. Theelectricity can be stored in the tissues, which act as abattery. The battery can be discharged in pulses. A ray can emit a shock into the body of a prey animal to stun it and make it easier to capture and eat, or into the body of a predator.
The torpedo electric organ, being composed of modified muscle cells, has proven highly useful in theneurobiological study of theneuromuscular junction. For example,agrin was first isolated fromTorpedo.[4]
Scribonius Largus, a first century physician, advised the use of a live torpedo ray as a headache remedy. He stated, "Headache even if it is chronic and unbearable is taken away and remedied forever by a live torpedo placed under the spot that is in pain."[5]
There are currently 13 recognized species in this genus:[6]
Two fossil species,T. acarinataAdnet, 2006 andT. pessantiAdnet, 2006, are known from theEocene of southwesternFrance.[7]
