Giant isopod

Amazing fact

When danger approaches, the giant isopod can curl into a ball with its hard shell facing out.

Aquarium of the Pacific

Giant isopod in its habitat (illustration)

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An illustration based on the real animal.

A little discovery to share.

When danger approaches, the giant isopod can curl into a ball with its hard shell facing out.

SourceAquarium of the Pacific — Giant Isopod

THE REAL WORLD

The real Giant isopod

Scientific name: Bathynomus giganteus
Japanese name: ダイオウグソクムシ
Group: Ocean animals

Class: Malacostraca
Order: Isopoda
Family: Cirolanidae
Genus: Bathynomus

Facts about the real animal.

It is an isopod, a relative of land-dwelling pill bugs.

鳥羽水族館 — ダイオウグソクムシ

It inhabits deep waters in the Gulf of Mexico.

鳥羽水族館 — ダイオウグソクムシ

How the Giant isopod lives

It crawls over the dark seafloor, using long antennae to find its way and prey. It eats fish carcasses and other debris that fall to the seafloor. It burrows into seafloor sediment for shelter. The female carries eggs in a pouch on her underside until they hatch.

Aquarium of the Pacific Monterey Bay Aquarium

Basic data

Size: Body length: 20–40 cm
Range: The Gulf of Mexico

鳥羽水族館

Where the Giant isopod has been recorded

Records: GBIF.org (CC0 and CC BY 4.0 records, retrieved 2026-11-07). Map: Natural EarthSee the records on GBIF

Where it livesWorld oceans North America Deep sea

Watch wild animals from a distance. Do not touch or feed them, and take care of the places where they live.

Names around the world

日本語: ダイオウグソクムシ
简体中文: 大王具足虫
繁體中文: 大王具足蟲
Español: Isópodo Gigante
Français: Bathynome géant
Deutsch: Riesenasseln
Italiano: Isopode gigante
Bahasa Indonesia: Kutu laut raksasa
Tiếng Việt: Chân giống khổng lồ

Names come from Wikidata and iNaturalist records. Where a language has no recorded name, we use the scientific name.

Sources and how we check

鳥羽水族館 — ダイオウグソクムシChecked: 2026-11-03
Monterey Bay Aquarium — Giant isopodChecked: 2026-11-05
Aquarium of the Pacific — Giant IsopodChecked: 2026-11-05

We check each fact against its source. The illustrations simplify how the real animal looks.

The classification (class, order, family, genus) follows Wikidata records, checked against GBIF. Classifications can change as research goes on.

The basic data are the values given in each source. They vary with how the animal is measured, whether it is male or female, and whether it lives in the wild or in captivity.

This page was translated from the original Japanese with the help of AI.

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When you meet the Giant isopod, look for this

Look at its antennae of different lengths.

Animals do different things from day to day, so you may not always see this.

Monterey Bay Aquarium

EXHIBIT INFORMATION

Places that keep or show the Giant isopod

Zoos, aquariums and other places whose official websites say they keep or show this animal.

Chubu

Numazu Deep Sea AquariumShizuoka, Japan · AquariumChecked 2026-11-03
Port of Nagoya Public AquariumAichi, Japan · Aquarium南館・深海ギャラリーで展示(2026年5月4日の公式コラムで展示中と案内。同年2〜3月に水槽トラブルで一時休止あり)Checked 2026-11-03

Displays can change with the animals’ health and the seasons. Check each facility’s official website before you go.