Isistius plutodus Garrick & Springer, 1964
Largetooth cookiecutter shark
photo by Sazima, I.

Family:  Dalatiidae (Sleeper sharks)
Max. size:  42 cm TL (male/unsexed)
Environment:  pelagic-neritic; depth range 60 - 200 m
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).
Diagnosis:  Dorsal spines (total): 0-0; Dorsal soft rays (total): 0-0. 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).
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').
IUCN Red List Status: Least Concern (LC); Date assessed: 12 May 2015 Ref. (120744)
Threat to humans:  harmless
Country info:   

Entered by: Carpenter, Kent E. - 15.06.92
Modified by: Capuli, Estelita Emily - 12.03.13
Checked by: Luna, Susan M. - 15.03.94

Source and more info: For personal, classroom, and other internal use only. Not for publication.

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