Onychoteuthis is a genus of squid in the family Onychoteuthidae. The type species is Onychoteuthis bergii. While the genus is found worldwide in tropical and subtropical oceans, they can also occur in the North Pacific Ocean. There were previously considered to be four species in the genus but there are now considered to be roughly 10. These squid are frequently observed in the surface waters at night and they are often caught using dipnet at nightlight stations. The young squid are usually the only specimens captured using standard midwater trawls, the older squid are apparently able to avoid the trawls. They can, however be collected from the air as individuals are able to leap high out of the water, sometimes even landing on the deck of a ship.
Most species belonging to the genus have a mantle length of under 200 mm, however the larger members may measure over 300 mm. The species in this genus have a densely muscular, cylindrical mantle which is tapered posteriorly into a pointed tail. Their skin is smooth and has no warts or wrinkles. The gladius can be seen through the skin along the midline of the back. The fins are rhomboid in shape, heart shape or arrow shaped and are pointed posteriorly. The species of Onychoteuthis have 8-10 prominent nuchal folds. Their tentacular clubs have 2 central series of 19-27 large, strong hooks on their manus and the adults either have no lateral sucker series no marginal series of suckers. or they are vestigial. The chitinous rings of the suckers on the arms is smooth, with no teeth. They have photophores in their mantle cavity with a small one placed anteriorly on the ink sac, another near the anus; a large one placed posteriorly on the intestine and a bilobed photophore located on the ventral surface of each eye.
The following species are included in the genus:
- Onychoteuthis aequimanus Gabb, 1868
- Onychoteuthis banksii (Leach, 1817), common clubhook squid
- Onychoteuthis bergii Lichtenstein, 1818
- Onychoteuthis borealijaponica Okada, 1927, boreal clubhook squid
- Onychoteuthis compacta (Berry, 1913)
- Onychoteuthis horstkottei Bolstad, 2010
- Onychoteuthis lacrima Bolstad & Seki, 2008
- Onychoteuthis meridiopacifica Rancurel & Okutani, 1990
- Onychoteuthis mollis (Appellöf, 1891)
- Onychoteuthis prolata Bolstad, Vecchione & Young, 2008
- Philippe Bouchet (2018). Bieler R, Bouchet P, Gofas S, Marshall B, Rosenberg G, La Perna R, Neubauer TA, Sartori AF, Schneider S, Vos C, ter Poorten JJ, Taylor J, Dijkstra H, Finn J, Bank R, Neubert E, Moretzsohn F, Faber M, Houart R, Picton B, Garcia-Alvarez O, eds. "Onychoteuthis Lichtenstein, 1818". MolluscaBase. World Register of Marine Species. Retrieved 13 March 2018.
- Bolstad, K.S.R.; Michael Vecchione; Richard E. Young & Kotaro Tsuchiya (2010). "Onychoteuthis Lichtenstein, 1818. Version 23 December 2010 (under construction)". The Tree of Life Web Project.
- P. Jereb; C.F.E. Roper, eds. (2010). Cephalopods of the World an Annotated and Illustrated Catalogue of Cephalopod Species Known to Date Volume 2 Myopsid and Oegopsid Squids (PDF). Food and Agriculture Organization Rome. p. 349. ISBN 978-92-5-106720-8.