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Cycloteuthis sirventi

Described by Joubin, 1919

Cycloteuthis sirventi is easily distinguished from species of Discoteuthis by the general shape which includes a tail. Maximum known size is 480 mm ML (Clarke, 1986). This is probably the most common member of the family but, nevertheless, little is known of its biology.

A cycloteuthid ...

  • with a distinct tail.
  • with a large visceral photophore.

A cycloteuthid ...

  • with a distinct tail.
  • with a large visceral photophore.

A second species, Cycloteuthis akimushkini Filippova, 1968, has been described. This description was based on a very large specimen and apparent differences between this species and C. sirventi may be due to size effects alone. This species is considered to be a synonym of C. sirventi at present.

Geographical distribution. Tropical and subtropical waters of the world's oceans.

Arms

  1. Large suckers from arm III with ca. 20 low, truncate teeth (larger distally) around entire margin.
  2. Tentacles
    1. Suckers nearly equal in size across manus of club.
    2. Suckers from club manus with ca. 20 teeth, pointed distally and truncated proximally.
  3. Head
    1. Beaks: Descriptions can be found here: Lower beak; upper beak.

  4. Mantle
    1. Tail present.

  5. Fins
    1. Fins large, oval, length about 80% of ML in subadults.

  6. Photophores
  7. Gladius
    1. Gladius with a secondary conus.

C. serventyi has a very distinctive paralarva. The second arms are very long and a thick, transparent dermal layer is present in the integument. Each eye is on a stalk but, unlike many cranchiids, the optic lobe is attached to the central brain and long retinal nerves connect it to the eye.

  • Clarke, M. R. 1986. A Handbook for the Identification of Cephalopod Beaks. Clarendon Press, Oxford. 273 pp.
  • Filippova, J. A. 1968. A new species of the genus Cycloteuthis. Malacol. Rev., 1: 119-124.
  • Nesis, K. N. 1982. Abridged key to the cephalopod mollusks of the world's ocean. 385,ii pp. Light and Food Industry Publishing House, Moscow. (In Russian.). Translated into English by B. S. Levitov, ed. by L. A. Burgess (1987), Cephalopods of the world. T. F. H. Publications, Neptune City, NJ, 351pp.
  • Young, R. E. and C. F. E. Roper. 1969. A monograph of the Cephalopoda of the North Atlantic: The family Cycloteuthidae. Smithsonian Contributions to Zoology No. 5:1-24.
  • Tree of Life Web Project. 2019. Cycloteuthis Joubin, 1919 . Cycloteuthis sirventi Joubin, 1919 . Version 26 March 2019 (temporary). http://tolweb.org/Cycloteuthis_sirventi/149702/2019.03.26 in The Tree of Life Web Project, http://tolweb.org/

Taxonomy

Superorder
Decapodiformes
Superfamily
Cycloteuthoidea