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Animal profile

Cookiecutter Shark

Isistius brasiliensis

ChondrichthyesOpen ocean, migrating nightly between depths of about a kilometre and near the surfaceLeast Concern

Field profile

The cookiecutter shark is a cigar-shaped dogfish rarely longer than fifty centimetres, with a luminous underside and enormous lower teeth. It takes round plugs of flesh from animals far larger than itself, including tuna, whales and seals. It rises to shallow water at night and retreats to depth by day.

Scope note

This is an editorial profile, not a diagnostic field-identification guide or a substitute for current conservation assessments. Follow the cited sources on each fact for the evidence trail.

Published field notes

2023-12-11

Cookiecutter Shark

The cookiecutter shark glows except for a dark collar

Its whole underside is covered in light organs that erase the shark's silhouette against the dim surface. A band of skin under the throat stays dark, and one hypothesis is that this unlit patch mimics a small fish and draws predators into range.

Read with evidence →

Cookiecutter Shark | Daily Animal Facts