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July 27, 2026Sources cited
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Science & Nature • Marine Biology

Blanket octopus

The blanket octopus is a pelagic genus of octopuses in the genus Tremoctopus, known for the female’s large web of skin between its arms and extreme sexual dimorphism.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 27, 2026|2 min read| Fact-checked

The blanket octopus is a pelagic genus of octopuses in the genus Tremoctopus, known for the female’s large web of skin between its arms and extreme sexual dimorphism. It lives in tropical and subtropical oceans, often in open water and sometimes near coral reefs. Four species are currently recognized, and the group is listed as least concern by the IUCN.

Description

Blanket octopuses are a genus of open-ocean cephalopods distinguished by the female’s long, transparent webbing that stretches between the arms. This feature gives the animal its common name and is used in defensive displays.

Distribution and habitat

They are found in tropical and subtropical oceans around the world. Sources describe them as pelagic animals that inhabit surface to mid-water layers and may also be seen near coral reefs.

Species and taxonomy

The genus Tremoctopus contains four recognized species. Common sources identify the blanket octopus as a group of pelagic octopuses rather than a single species.

Behaviour and biology

Blanket octopuses are carnivorous and are noted for their unusual size difference between males and females. The species is also known for uncommon defensive behaviour and for its rarity in human sightings.

Key facts

  • Blanket octopuses are named for the broad, blanket-like web of skin connecting the female’s arms.
  • They are pelagic, meaning they live in the open ocean rather than on the seafloor.
  • The group shows extreme sexual dimorphism: females can grow to about 6 feet, while males are only about 1 inch long.
  • They occur in tropical and subtropical waters worldwide, including around reefs and surface to mid-water zones.
  • The genus includes four recognized species.
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Canadian context

Blanket octopuses are not native to Canada, but they are of interest to Canadian readers through ocean biology, aquarium education, and marine conservation coverage.

Frequently asked questions

What is a blanket octopus?
A blanket octopus is a pelagic octopus in the genus Tremoctopus, known for the female’s web-like skin between the arms.
Where do blanket octopuses live?
They live in tropical and subtropical oceans worldwide, usually in open water and sometimes near coral reefs.
How many species are there?
There are four recognized species in the genus Tremoctopus.
How big are blanket octopuses?
Females can reach about 6 feet in length, while males are tiny, around 1 inch long.
What do blanket octopuses eat?
They are carnivores; sources commonly describe them as feeding on smaller fish and other marine animals.
Are blanket octopuses endangered?
They are listed as least concern on the IUCN Red List.

References

  1. National Geographic — https://www.nationalgeographic.com/animals/invertebrates/facts/blanket-octopus
    Supports: Common name, scientific name, size, diet, and conservation status.
  2. Ocean Conservancy — https://oceanconservancy.org/blog/2023/01/05/meet-the-blanket-octopus/
    Supports: Genus, number of species, habitat, and conservation status.
  3. Great Barrier Reef Foundation — https://www.barrierreef.org/the-reef/animals/blanket-octopus
    Supports: Habitat, diet, and conservation status.
  4. Science and the Sea — https://www.scienceandthesea.org/program/big-blanket
    Supports: Sexual dimorphism, size comparison, habitat, and defensive use of stinging tentacles.