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Isistius plutodus

No common name
Collection Details

Specimens

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Taxonomic Hierarchy

Chondrichthyes (Cartilaginous Fishes) Squaliformes (Dogfish Sharks) Dalatiidae (Kitefin Sharks) Isistius Isistius plutodus

Description

This species account was compiled from FishBase (Froese, R. and D. Pauly. Editors. 2025. FishBase. World Wide Web electronic publication. www.fishbase.org, version 04/2025.) and processed using AI-assisted text extraction. It may contain errors in spelling, punctuation, or formatting. When citing, please reference the original source rather than this page. Learn more about our species accounts.

Characters

Body shape: elongated. The largetooth cookiecutter shark Isistius plutodus has no collar marking around throat, a small asymmetrical caudal fin with a short ventral lobe less than half the length of dorsal caudal margin, bigger mouth and gigantic lower teeth (proportionately the largest in any living shark) in 19 rows (upper teeth = 29 rows). Eyes set well forward on head, with extensive anterior binocular field. Pectoral fins rounded, pelvic fins smaller than dorsal fins. As with the other member of the genus Isistius, it has a characteristic small cigar-shaped body with two small close-set spineless dorsal fins far posterior on back, no anal fin, huge, triangular-cusped teeth without blades, short, bulbous snout and a unique suctorial lips (Ref. 247).

Distribution

Atlantic: off Alabama, USA and the Gulf of Mexico; including Brazil and West Sahara and off Azores. Northwest Pacific: off Okinawa, Japan and Australia (NSW). A very rare species (Ref. 52580).

Habitat Associations

Marine. pelagic-neritic. depth range 60-200 m.

Biology

A very rare species known only from few localities in epipelagic waters. Apparently feeds on small epibenthic and epipelagic invertebrates and fish. Its powerful jaws, big mouth and enormous lower teeth enable it to bite off large portion of its prey in one sweeping motion. A facultative ectoparasite evidenced by its suctorial lips and feeding apparatus. It has extremely short snout and anteriorly positioned eyes which allows for binocular vision (Ref. 247). Caught by mid-water trawl (Ref. 55584). Ovoviviparous (Ref. 205). Has large oily liver which helps it to become neutrally buoyant (`hepatic float').
Reproductive mode: dioecism; fertilization: internal (oviduct); bearers (internal live bearers). Distinct pairing with embrace (Ref. 205).
IUCN Red List Status: Least Concern (LC), assessed 2015-05-12. Resilience: Low (Fec assumed to be <100).

Commercial or Environmental Importance

Fisheries: of no interest.

References

Breder, C.M. and D.E. Rosen (1966) Modes of reproduction in fishes. T.F.H. Publications, Neptune City, New Jersey. 941 p.
Compagno, L.J.V. (1984) FAO Species Catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Part 1 - Hexanchiformes to Lamniformes. FAO Fish. Synop. 125(4/1):1-249. Rome, FAO.
Zidowitz, H., H.O. Fock, C. Pusch and H. von Westernhagen (2004) A first record of Isistius plutodus in the north-eastern Atlantic. J. Fish Biol. 64(5):1430-1434.
Hoese, D.F., D.J. Bray, J.R. Paxton and G.R. Allen (2006) Fishes. In Beasley, O.L. and A. Wells (eds.) Zoological Catalogue of Australia. Volume 35 Australia: ABRS & CSIRO Publishing, 2178 p.

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