# Cookiecutter Shark (*Isistius brasiliensis*)

> The cookiecutter shark (Isistius brasiliensis) is a small deep-sea shark that bites round plugs of flesh from whales, tuna, and submarines. Adults reach 50 cm, glow with bioluminescence, and are Least Concern.

- **Category:** Fish
- **Conservation status (IUCN):** Least Concern
- **Range:** Tropical oceans worldwide.
- **Canonical page:** https://globalanimalguide.org/animals/cookiecutter-shark/
- **Last reviewed:** 2026-07-16

## Scientific classification

- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Chondrichthyes
- **Order:** Squaliformes
- **Family:** Dalatiidae
- **Genus:** Isistius

## Facts at a glance

| Attribute | Value |
| --- | --- |
| Scientific name | Isistius brasiliensis |
| Diet | Carnivore (ectoparasitic bites) |
| Habitat | Open ocean midwaters |
| Lifespan | 20–30 years |
| Weight | 0.5–1 kg |
| Top speed | up to 15 km/h |
| Conservation status | Least Concern (IUCN) |

## Living melon baller

Lower teeth fuse into a saw-like plate that scoops cylindrical plugs of meat from much larger animals. Photophores on the belly hide the silhouette from below.

## Squid, fish, and flesh bites

Whole small prey are swallowed, but adults also ambush large animals — whales, dolphins, tuna — leaving crater scars. Even sonar domes and rubber seals get sampled.

## Tropical oceanic midwaters

Worldwide in warm deep water, rising vertically at night toward surface prey. Migration follows the deep scattering layer.

## Tiny terror, stable numbers

Least Concern with vast habitat and no fishery. Famous bite scars on submarines and whales document their bold parasitic feeding.

## Frequently asked questions

### How does a cookiecutter shark bite?

It latches on and spins, carving a round plug of flesh with serrated lower teeth.

### Why do whales have round scars?

Many come from cookiecutter sharks and similar species taking plug bites at night.

### Do cookiecutter sharks glow?

Yes — belly photophores match downwelling light, hiding the shark's silhouette.

### How big is a cookiecutter shark?

About 40–50 cm — tiny compared with the whales they scar.

### Have cookiecutters damaged submarines?

Yes — they have bitten rubber sonar domes and cables on navy vessels.

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Source: Global Animal Guide (https://globalanimalguide.org/animals/cookiecutter-shark/). Licensed CC BY-NC 4.0 — free for non-commercial reuse with attribution.