---
title: Bandit Coral Crab (Tetralia nigrolineata)
scientific_name: Tetralia nigrolineata
common_name: Bandit Coral Crab
taxon: Crabs
published: 2024-09-23T15:50:52.164Z
updated: 2026-08-15T16:49:01.603Z
tags: Bandit Coral Crab, Tetralia nigrolineata, Crabs, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/crustaceans/crabs/bandit-coral-crab
---

# Bandit Coral Crab (*Tetralia nigrolineata*)

## Quick facts

- **Group:** Crabs (*Brachyura*)
- **Size:** up to 2 cm
- **Depth:** 1-25 m
- **Diet:** Omnivore
- **Activity:** Nocturnal
- **Rarity:** Common
- **Habitat:** Between the branches of Acropora table corals
- **Reproduction:** Egg layer, Gonochoric

## How to recognise it

- small flat crab, pale cream with a dark bandit mask across the eyes
- smooth shell, wider than long, with no spines
- always in an Acropora colony, moving on the underside of the branches
- width up to 2 cm

A pale crab with a dark band across the eyes, living on the underside of an Acropora table and moving with the colony rather than on it.

It is one of the two guard crabs on this reef, and it works a different coral from the other. *Trapezia* holds the branching Pocillopora heads; *Tetralia* lives on the flat plate corals, wedged in the narrow space between branches that a table coral leaves.

The job is the same. The crab defends its colony against the animals that eat it - crown-of-thorns starfish, coral-eating snails, nudibranchs - and it clears sediment that would smother the tissue underneath. Colonies with resident crabs come out of a starfish attack alive; colonies without them do not.

In exchange it eats the coral's fatty mucus and the particles caught in it, and never leaves. Two centimeters (0.8 in) of crab tied to one colony for life, and dying with it when the coral does.

## Also known as

- **English:** Bandit coral crab
- **French:** Crabe bandit des coraux
- **Chinese:** 黑線擬梯形蟹

## Scientific synonyms

- *Tetralia glaberrima f. nigrolineata* Serène & Pham, 1957
- *Tetralia glaberrima f. obscura* Patton, 1966
- *Tetralia glaberrima obscura* Serène, 1984

## Range

East China Sea, New Caledonian Exclusive Economic Zone, South Pacific Ocean

---

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