Rare and Elusive CookieCutter Shark Leaves a Round Wound in Its Prey
When we think of shark bites, we often think of the jagged teeth that tear the skin. However, this is not the case with the cookie cutter shark (Isistius brasiliensis). Although elusive, the cookie cutter shark certainly leaves its mark. Spotted on larger fish like tuna and swordfish, this shark takes a near-perfect circular bite from its prey, leaving behind a cookie cutter-like shape.
Although the cookie cutter shark is rarely seen, new research published in Advances in Marine Ecology Series from the University of Hawaii integrates like Hawaii (Hawaiian knowledge) and ‘ōlelo Hawai’i (Hawaiian language) with Western marine sciences to provide more knowledge about I. brasiliensis on the surface.
“What makes this species so fascinating is that we almost never see the shark itself,” Justin Suca, assistant professor of oceanography at UH Mānoa, said in a press release. “We learn this by studying when and where these bite marks appear.”
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Learn from the bite of the cookie cutter shark
Tuna with shark bite cookie cutter
(Image courtesy of the University of Hawaii)
Cookiecutter sharks are rather small compared to white sharks or tiger sharks. According to the Shark Research Institute, male cookie cutter sharks reach a maximum length of around 1.3 feet, while females can reach 1.6 feet. They have bulbous snouts and may have 25 to 31 rows of sharp triangular teeth on their lower jaw.
It’s these intimidating teeth that leave circular wounds in the shark’s prey. These injuries also help researchers better understand this small predator.
Cookie-cutter sharks hunt better without the Moon
For this study, the research team analyzed a larger data set than in previous research. The team examined bite patterns recorded in Hawaii’s longline fisheries — a fishing method that uses extremely long lines and thousands of bait hooks to catch species such as tuna — over several years.
“I have been intrigued by these little sharks for over 40 years, when I first heard about them as a graduate student in oceanography at UH Mānoa, and we were encountering them in net hauls,” said Donald R. Kobayashi of NOAA’s Pacific Island Fisheries Science Center (PIFSC) in a press release. “These enigmatic creatures have resisted formal study due to their habitat, behavior, and apparent rarity, so it is very rewarding to personally contribute solid scientific knowledge to understanding them and their habits!”
The results indicated that cookiecutter sharks typically attack their prey at night and attack most often when there is little or no moonlight. According to the research team, this builds on previous research that links cookie-cutter shark bites to humans during moonless nights.
These results, which were published in a 2024 PLOS One study, suggest that cookiecutter sharks primarily hunt on moonless nights, and although bites on humans are very rare, the majority occur in Hawaii’s ocean channels.
Indigenous knowledge and modern science working together
In addition to scientific research, the team analyzed historical Hawaiian-language newspapers (nūpepa) and other Hawaiian-language sources for evidence of past shark bites. Although no references have been identified, the team believes that Hawaiian ancestors likely knew about the bite of the cookie cutter shark.
“Our kūpuna (elders) may never have encountered the shark itself,” Suca, J. Hau’oli Lorenzo-Elarco, assistant professor of ‘ōlelo Hawai’i at Honolulu Community College, said in a news release. “But they almost certainly encountered the evidence he left behind, the distinctive bite marks on the fish they brought in from offshore.”
From this study, the research team gave the cookie cutter shark a new name: nahunaiki, meaning “small bites.” They also created a Hawaiian proverb (ʻōlelo noʻeau) about the shark: Muku ka malama, nanahu ka nahunaikio o ka pō, When the new moon appears, the cookie cutter shark bites.
This research highlights how indigenous knowledge and modern science can collaborate on new discoveries.
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