Thysanoteuthis rhombus   Troschel,  1857 (Squid)
Organism information awaits expert curation
Class: Cephalopoda

Image copyrights: FAO

Size: Mantle length 700 mm; length 100 cm.

Weight: 12.25 kg (female)

Thick cylindrical muscular mantle, wide anteriorly and gradually tapering to a blunt end posteriorly. The fins are long and occupy continuously the entire length of the mantle along the sides. The shape of the fin is characteristically rhombic being very broad at the middle and tapering towards the anterior and posterior ends. The head is shorter than its width. Eyes are prominent. The oral arms are long with cirrate trabeulate protective membranes. The outer lateral arms are the longest and the inner dorsal arms are the shortest and provided with a crest like muscular projection at the base of each arm. The other arms are intermediary in length and devoid of such structures. All the arms are with two rows of suckers and the sucker rings are with 20-26 sharp teeth. The funnel and mantle locking apparatus is typical and the cartilage is characteristically ‘-1’ shaped. The tentacles are weak and the clubs are slightly expanded in the middle, with four rows of suckers; sucker rings with 15-20 sharp teeth.

Synonym (s)
Cirrobrachium filiferum Hoyle, 1904
(Junior synonym)
Thysanoteuthis elegans Troschel, 1857
(Junior synonym)

Common Name (s)
• Diamond Squid (English)
• Diamondback Squid (English)
Economic Importance and Threats

Habitat:  Pelagic
Prey:  Benthic crustaceans and finfishes.
Predator:  Finfishes (Alepisaurus ferox, Tylosurus sp., Prionace glauca, Coryphaena hippurus, Makaira mazara, Makaira nigricans, Katsuwonus pelamis, Thunnus albacares, Thunnus obesus, Thunnus thynnus, Sphyrna zygaena and Xiphias gladius), Mammals (Pseudorca crassidens, Stenella attenuata, Steno bredanensis, Physeter macrocephalus), Molluscs (Dosidicus gigas, Hyaloteuthis pelagica, Sthenoteuthis oualaniensis, Sthenoteuthis pteropus), Sea bird (Pachyptila desolata).


• Tamil Nadu, Gulf of Mannar, Off Veerapandianpatnam INDIA (Record: 30/06/1994) (Depth: -60 mts)

Literature Source(s)
  • Kasim, MH; Marichamy, R; Rajapackiam, S and Balasubramanian, TS (1998) Rare squid, Thysanoteuthis rhombus Troschel from the Gulf of Mannar, India Journal of the Marine Biological Association of India The Marine Biological Association of India, Cochin 39(1&2) 182-184 Available at - NIO, Goa
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -
  • Sealifebase Available at -
  • Untawale, AG; Dhargalkar, VK and Deshmukhe, GV (2000) Prioritization of potential sites for marine biodiversity conservation in India Setting biodiversity conservation priorities for India: Summary of the findings and conclusions of the biodiversity conservation prioritization project World Wide Fund for Nature - India, New Delhi (India) Available at -
  • Silas, EG; Sarvesan, R and Meiyappan, MM (1985) Oceanic Squids Cephalopod bionomics, fisheries and resources of the exclusive economic zone of India Bulletin of Central Marine Research Institute CMFRI 37 140-145 Available at -

Page last updated on:2011-09-12

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