--- title: "Cookiecutter Shark (Isistius brasiliensis) | AnimalTracks.wiki" description: "A shark up to 56 cm long that glows underneath to lure big animals close, then spins to cut a round plug out of them." image: "https://animaltracks.wiki/images/animals/cookiecutter-shark-1.webp" published: "2026-10-10" updated: "2026-10-11" --- # Cookiecutter Shark (*Isistius brasiliensis*) > **Status**: Checked against 5 sources, listed under Sources below. > **Tagline**: A shark up to 56 cm long that glows underneath to lure big animals close, then spins to cut a round plug out of them. > **Soundtrack Vibe**: 80s Pop & Dance Anthem // Dead Or Alive, "You Spin Me Round (Like a Record)" > **Soundtrack Links**: [Spotify](https://open.spotify.com/track/1ChulFMnwxoD74Me8eX2TU) > **Vibe Match**: A cookiecutter shark grips with its lips and upper teeth, then spins its body to cut a round plug out of its prey. You Spin Me Round turns that move into a dance floor. ## Biological Superpowers & Stats - **Taxonomy**: *Isistius brasiliensis* - **Danger Level**: Medium - **Conservation Status**: Least Concern ([IUCN Red List](https://doi.org/10.2305/iucn.uk.2018-2.rlts.t41830a2956761.en)) - **Superpower**: A glowing underside that lures big animals in, then a spin that carves out a cookie-shaped plug - **Habitat**: Tropical and subtropical oceans worldwide, deep by day and near the surface at night - **Diet**: Plugs of flesh cut from large fish, whales and seals, plus squid - **Tags**: shark, cartilaginous, bioluminescent, pelagic, bizarre-anatomy ## Natural History & Behavior ## Bait with teeth The cookiecutter shark turns its own belly into a lure. Its underside is covered in photophores, tiny light-producing organs that give off a greenish glow. The only gap on the underside is a dark collar around the gill region. The glow attracts fish, whales and sharks, and it appears similar to a small fish. The shark bites when they come close. > **Cookie-shaped hole** > It grips with sucking lips and upper teeth, then spins its body to cut a cookie-shaped plug out of its prey with its larger lower teeth. The prey is left with a perfectly round, cookie-cutter-shaped hole in its side. ## A small shark with huge targets Males grow to a maximum of 42 cm and females to 56 cm. Fifteen caught off Hawaii in 2013 weighed 213 g on average. The small, cigar-shaped shark can be called a parasite, because it feeds on larger animals without killing them. The Florida Museum lists marlin, wahoo, tuna, sharks, stingrays, seals, whales and dolphins among its prey. It also eats squid, and many squid remains found in cookiecutter stomachs were estimated to come from squid often as large as the sharks themselves. There are even reports of crater marks on the sonar domes of nuclear submarines. ## Up at night, down by day Cookiecutter sharks live in tropical and subtropical oceans around the world. They are found from the Bahamas to southern Brazil in the western Atlantic, and from Mauritius to New Guinea, New Zealand, Japan and the Hawaiian Islands in the Indo-Pacific. By day they stay below 1,000 m. At night they rise to the surface waters to feed, a daily trip scientists call vertical migration. Of the six bites by cookiecutter sharks (genus *Isistius*) on live people in Hawaiian waters, five came with the moon set and after dark. Even so, the Florida Museum considers the shark harmless to humans because of its size and deep-water habits. ## Teeth that go down the hatch The teeth are connected at the base and lost as one complete unit, rather than one at a time like most sharks. It swallows its shed lower teeth, which is thought to help maintain the calcium in its body. A litter holds 6 to 12 live young. The IUCN Red List rates the species Least Concern. ## Frequently Asked Questions ### How big does a cookiecutter shark get? Females are the larger sex. FishBase gives a maximum total length of 56 cm for a female and 42 cm for a male. *(Source: [FishBase]())* ### Do cookiecutter sharks bite people? Very rarely. A 2024 study counted seven confirmed attacks on live people ever documented, six of them in Hawaiian waters between 2009 and 2023. *(Source: [Minaglia & Liegl 2024]())* ### Why does a cookiecutter shark swallow its own teeth? It sheds its lower teeth as one complete set and swallows them. The Florida Museum says this is thought to help the shark keep up its calcium levels. *(Source: [Florida Museum of Natural History]())* ## Sources 1. [Kyne (2018). Isistius brasiliensis. The IUCN Red List of Threatened Species 2018: e.T41830A2956761.]() 2. [Carlisle et al. (2021). Integrating multiple chemical tracers to elucidate the diet and habitat of Cookiecutter Sharks. Scientific Reports.]() 3. [Minaglia & Liegl (2024). Moonless night sky increases Isistius species (cookiecutter shark) and live human contact. PLOS ONE.]() 4. [Cookiecutter Shark (Isistius brasiliensis). Florida Museum of Natural History.]() 5. [Isistius brasiliensis (Quoy & Gaimard, 1824) Cookie cutter shark. FishBase.]() *Published October 10, 2026. 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