''Isistius'' is a
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
dogfish sharks in the
family Dalatiidae. They are commonly known as
cookiecutter sharks. Members of the genus are known for their unusual behaviour and dentition.
Species
*''Isistius brasiliensis''
Quoy & Gaimard, 1824 (
cookiecutter shark)
*''Isistius plutodus''
Garrick & S. Springer, 1964 (
largetooth cookiecutter shark)
*†''
Isistius triangulus''
Probst, 1879
*†''
Isistius trituratus''
Winkler, 1876
Habits
The
cookiecutter sharks, or cigar sharks, are unusual in the manner in which they replace their teeth. Instead of replacing teeth singly as they get damaged or lost, for example in hunting, such sharks replace the whole set. They can repeat such replacement throughout their lifetimes.
Cookiecutter sharks often attack large shoals of fish, but have been known to circle fishing vessels to get an easy meal. They are particularly notorious for biting small chunks off of a prey animal in passing. Large prey, such as
swordfish and
cetacean
Cetacea (; , ) is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively c ...
s, may bear several healed wounds from such bites.
[Papastamatiou Yannis P., Wetherbee, Brad M., O'Sullivan, John, Goodmanlowe Gwen D. Lowe, Christopher G.; Foraging ecology of Cookiecutter Sharks (Isistius brasiliensis) on pelagic fishes in Hawaii, inferred from prey bite wounds.; Environmental Biology of Fishes, Volume 88, Number 4, 361-368, ]
Weaker prey may be injured enough to be weakened until they are unable to swim properly. They then are prone to sinking, enabling these sharks to gorge. ''Isistius'' species can eat half of their own body weight at a time.
See also
*
List of prehistoric cartilaginous fish
References
Extant Thanetian first appearances
Shark genera
Taxa named by Theodore Gill
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