Temporal range: Early Eocene–Recent
|A Common torpedo (T. torpedo)|
Torpedo is a genus of rays, commonly known as electric rays, torpedo rays, or torpedoes. It is the sole genus of the family Torpedinidae. They are slow-moving bottom-dwellers capable of generating electricity as a defense and feeding mechanism. Between 15 and 22 extant species are described.
The naval weapon known as the torpedo was named after this genus, whose own name is derived from the Latin word meaning "numb" or "paralysed", presumably the sensation one would feel after experiencing the ray's electric shock.
The largest species is the Atlantic torpedo, Torpedo nobiliana, which can grow to a weight of 90 kg (200 lb) and deliver a 220-volt electric shock. Electric rays have patches of modified muscle cells called electroplaques that make up an electric organ. These generate an electric gradient, similar to the normal electric potential across most cell membranes, but amplified greatly by its concentration into a very small area. The electricity can be stored in the tissues, which act as a battery. 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.
Use in neurobiological research
The torpedo electric organ, being composed of modified muscle cells, has proven highly useful in the neurobiological study of the neuromuscular junction. For example, agrin was first isolated from Torpedo.
Torpedo rays are flat like other rays, disc-shaped, with caudal fins that vary in length. Their mouths and gill slits are located on their undersides. Males have claspers near the base of the tail. Females are ovoviviparous, meaning they form eggs but do not lay them. The young "hatch" within her body and she bears them live.
The currently recognized species in this genus are:
- Torpedo adenensis M. R. de Carvalho, Stehmann & Manilo, 2002 (Aden Gulf torpedo)
- Torpedo alexandrinsis Mazhar, 1987 (Alexandrine torpedo)
- Torpedo andersoni Bullis, 1962 (Florida torpedo)
- Torpedo bauchotae Cadenat, Capapé & Desoutter, 1978 (Rosette torpedo)
- Torpedo californica Ayres, 1855 (Pacific electric ray)
- Torpedo fairchildi F. W. Hutton, 1872 (New Zealand torpedo)
- Torpedo formosa D. L. Haas & Ebert, 2006 (Taiwan torpedo)
- Torpedo fuscomaculata W. K. H. Peters, 1855 (Black-spotted torpedo)
- Torpedo mackayana Metzelaar, 1919 (Ringed torpedo)
- Torpedo macneilli Whitley, 1932 (Shorttail torpedo)
- Torpedo marmorata A. Risso, 1810 (Marbled electric ray)
- Torpedo microdiscus Parin & Kotlyar, 1985 (Smalldisk torpedo)
- Torpedo nobiliana Bonaparte, 1835 (Atlantic torpedo)
- Torpedo panthera Olfers, 1831 (Panther electric ray)
- Torpedo peruana Chirichigno F., 1963 (Peruvian torpedo)
- Torpedo puelcha Lahille, 1926 (Argentine torpedo)
- Torpedo semipelagica Parin & Kotlyar, 1985 (Semipelagic torpedo)
- Torpedo sinuspersici Olfers, 1831 (Variable torpedo)
- Torpedo suessii Steindachner, 1898
- Torpedo tokionis S. Tanaka (I), 1908 (Trapezoid torpedo)
- Torpedo torpedo Linnaeus, 1758 (Common torpedo)
- Torpedo tremens F. de Buen, 1959 (Chilean torpedo)
- Froese, Rainer, and Daniel Pauly, eds. (2009). "Torpedinidae" in FishBase. January 2009 version.
- "Torpedo". Integrated Taxonomic Information System. Retrieved October 12, 2008.
- Froese, Rainer, and Daniel Pauly, eds. (2011). Species of Torpedo in FishBase. February 2011 version.
- Kidd, D.A. (1973). Collins Latin Gem Dictionary. London: Collins. ISBN 0-00-458641-7.
- Sanes; Lichtman (1999). "Development of the vertebrate neuromuscular junction". Annual Review of Neuroscience 22 (1). doi:10.1146/annurev.neuro.22.1.389.
- Froese, Rainer, and Daniel Pauly, eds. (2013). Species of Torpedo in FishBase. April 2013 version.
- ADNET, S. (2006): Nouvelles faunes de Sélaciens (Elasmobranchii, Neoselachii) de l'Eocène moyen des Landes (Sud-Ouest, France). Palaeo Ichthyologica, 10