Binominal nomenclature

• Thysanoteuthis rhombus
• Troschel,1857

Scientific classification

• Kingdom: Animalia
• Phylum: Mollusca
• Class: Cephalopoda
• Order: Oegopsida
• Family: Thysanoteuthidae
• Genus: Thysanoteuthis
• Species: T. rhombus

Thysanoteuthis rhombus, also identified as the diamond squid, rhomboid squid, or diamondback squid is a large variety of squid from the family Thysanoteuthidae which is found worldwide, throughout subtropical waters and tropical.

T.rhombus is provided with its name for the appearance of the first that runs the length of the mantle. They are a fast-growing species with a lifespan of around 1 year. The diamond squid is the only cephalopod varieties remembered to be monogamous. T.rhombus often prey on fish and other small cephalopods at varying water depths. This species is commercially fished in Japan, especially in the Sea of Japna and Okinawa. 

The predators that feed on T.rhombus add various species of ommastrephid squids, dolphin fish, lancetfish, tuna, swordfish, Gempylus serpens, and sharks. Other predators include mammals such as dolphins, rough-toothed dolphins, false killer whales, and sperm whales. In subsurface water levels, T. rhombus juveniles were found to feed on crustaceans, small cephalopods, and the Diamond squid was found to consist mostly of nonactive fishes at water depths of 400 to 650m.