---
title: Red Hermit Crab (Pagurixus ruber)
scientific_name: Pagurixus ruber
common_name: Red Hermit Crab
taxon: Hermit crabs
published: 2025-09-24T12:53:43.324Z
updated: 2026-08-15T17:14:34.310Z
tags: Red Hermit Crab, Pagurixus ruber, Hermit crabs, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/crustaceans/hermit-crabs/red-hermit-crab
---

# Red Hermit Crab (*Pagurixus ruber*)

## Quick facts

- **Group:** Hermit crabs (*Paguroidea*)
- **Size:** up to 2 cm
- **Depth:** 1-20 m
- **Diet:** Detritivore
- **Activity:** Nocturnal
- **Rarity:** Uncommon
- **Habitat:** Rubble and dead coral in shallow water
- **Reproduction:** Egg layer, Gonochoric

## How to recognise it

- tiny hermit crab, red-brown with paler leg joints
- in very small gastropod shells, often barely bigger than a grain of rice
- deep in rubble rather than out on rock
- length up to 2 cm

A red-brown hermit crab small enough to live in a shell the size of a grain of rice, working the inside of rubble rather than the surface.

At this scale the shell problem changes character. A crab of two centimeters can use shells that larger species have long outgrown, and it competes not with them but with dozens of other small hermits and with the snails still occupying the shells. Populations of tiny hermit crabs are limited by shell supply more directly than by food.

It eats detritus and algal film in the gaps between rubble pieces, and rarely comes out where a torch can find it.

Species at this size are separated by the shape of the claws and the pattern on the eyestalks, which means most photographs cannot be identified at all - and the small hermit crab fauna of this sea is certainly larger than the number of species anyone has named.

## Also known as

- **Japanese:** クレナイヒメホンヤドカリ
- **Chinese:** 紅色准寄居蟹

## Range

Mozambique Channel, South Pacific Ocean

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*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/crustaceans/hermit-crabs/red-hermit-crab)*
*Updated: August 15, 2026*