Cycloteuthis is a genus of squid in the family Cycloteuthidae. It is distinguished from the genus Discoteuthis by the presence of a tail on the mantle. The species C. akimushkini is currently considered a junior synonym of C. sirventi, however this is inconclusive and the World Register of Marine Species has C. akimushkini as a valid species.
The genus contains bioluminescent species.[1]