Thysanoteuthis is a genus of large, muscular squids (to at least 100 cm ML) found throughout tropical and subtropical regions of the world's oceans. These animals are found in near-surface waters during the night and midwaters during the day. The arms are rather short and and the fins are very large, triangular (or diamond-shaped together; hence the common name), extending along the full length of the mantle. Thysanoteuthis major is fished commercially in the Sea of Japan and off Okinawa.
Other names
- Mantle very muscular
- Mantle-locking cartilage has sideways or "lazy" T shape (unique to the genus/family among all oegopsid squids)
Ventral view of funnel locking-cartilage of T. major (Central North Pacific); anterior is to the left. R. E. Young.
Until recently, Thysanoteuthis was considered to have a single cosmopolitan species, T. rhombus. However, Deville et al. (2024) reported on cryptic diversity in this genus and recognised three species:
- T. major (North Pacific and Indian Ocean)
- T. rhombus (Atlantic and Mediterranean)
- T. cf. filiferum (South Pacific)
A full list of the species historically attributed to or affiliated with this genus can be found here on the World Register of Marine Species.
- Deville, D., Mori, S., Kawai, K., Escánez, A., Macali, A., Lishchenko, F., ... & Sanchez, G. (2024). Cryptic biodiversity in the commercial diamondback squid Thysanoteuthis rhombus Troschel 1857. Reviews in Fish Biology and Fisheries, 34(1), 293-313.
- Naef, A. 1921-23. Cephalopoda. Fauna e Flora de Golfo di Napoli. Monograph, no. 35, 863 pp.
- Nigmatullin, C. M. and A. I. Arkhipkin. 1998. A review of the biology of the diamond back squid, Thysanoteuthis rhombus (Oegopsida: Thysanoteuthidae).p. 155-181. In: (T. Okutani, Ed.) Contributed Papers to International Symposium on Large Pelagic Squids. Japan Marine Fishery Resources Research Center, Tokyo.
- Suzuki, S., H. Misaki and T. Okutani. 1979. Studies on early life history of decapodan Mollusca. VIII. A supplementary note on floating egg mass of Thysanoteuthis rhombus Troschel in Japan - The first underwater photography. Venus 38: 153-155.
- Toll, R. B. 1998. The gladius in teuthoid systematics. Smithson. Contr. Zool., No. 586: 55-68.
- Troschel, F. H. (1857). Bemerkungen über die Cephalopoden von Messina. Archiv für Naturgeschichte, Berlin. 23(1): 41-76., available online at https://www.biodiversitylibrary.org/page/7171925
page(s): 69 - Wakabayashi, T., Tsuchiya, K., & Segawa, S. (2005). Morphological changes with growth in the paralarvae of the diamondback squid Thysanoteuthis rhombus Troschel, 1857. Phuket Marine Biological Center Research Bulletin, 66, 167–174.