The cookiecutter shark is a small, cigar-shaped, deep-water shark possessing a strong jaw. However, what makes this sharks uniqueness and distinguishes it from its close relatives is the way this jaw is used. They use their strong, jointed-together teeth by biting cookie-shaped chunks off large animals such as orcas, dolphins, great white sharks, tunas…and are the only known shark to feed that way. That’s not the only extraordinary feature of the cookiecutter shark though, as they’re also able to produce green light on their belly using photophores to blend with the sun or moonlight and hide from predators. We also know they spend their days in deep waters around 1000–3700 m (3,280–12,139 ft) and undergo a vertical migration up to 85 m (279 ft) to feed every night, rarely venturing to the surface.
At-A-Glance
Scientific Name – Isistius brasiliensis
Size – females 5 in/39 cm and males 20 in /50+ cm.
Habitat – Deep, tropical waters and warm-temperate waters around the globe, more common around islands.
Diet: Small fish and squid, but also all sorts of megafauna! More info in the science in the spotlight section.
Reproduction – Oviparous – embryos being sustained by yolk (and not placenta like viviparous species) until birth. Long gestation periods bring litters of 6-12 pups. Males attain sexual maturity at around 36 cm (14 in), and females at a length of 39 cm (15 in).
Lifespan – Around 25 years.
IUCN Listing – Least concern.
Protection – None, as no intrinsic fishing value.
Bet You Didn’t Know…
- Cookiecutter shark attacks have also been reported on underwater cables, oceanographic equipment, and even on cold-war military submarines!
- This species was first found off Brazil by French naturalists Jean René Constant Quoy and Joseph Paul Gaimard during their 1817–1820 expedition on the Uranie, hence the Latin name Isistius brasiliensis.
- Cookiecutters regularly replace their teeth like any other sharks, but as their set of teeth are jointed (upper and lower jaw are fused separately), they have to replace all the 25-30 teeth at once. To compensate for the massive energy loss, these sharks can swallow their old set of teeth to recycle the calcium.
- The dark collar behind the sharks’ head, not being bioluminescent like the rest of the shark’s belly, could be a lure mimicking a smaller fish in order to attract large predators.
- The cookiecutter shark has been in contact a couple of times with humans, leaving bite marks on bodies as well as on fishing gear.
Ready To Dive In?
- Due to its deep location and rarity, there’s no dive spot to see a cookiecutter shark. However, swimmers in the Alenuihaha Channel and Kaiwi Channel in the Hawaiian Islands have been bitten by cookiecutter sharks on multiple occasions.
Science In The Spotlight
Take a more detailed look at the cookiecutter shark’s unique hunting technique!
After Bites Cookiecutter Shark Quiz
Take the quiz and test your new found knowledge.
Written by Emmanuel Ballif. Photos by Brittanica, Florida Museum, Rob Zugaro, Oceana, Oceanbites, The Guardian, Wikimedia Commons.