---
title: Black-fingered Coral Crab (Cymo melanodactylus)
scientific_name: Cymo melanodactylus
common_name: Black-fingered Coral Crab
taxon: Crabs
published: 2026-08-08T21:11:47.679Z
updated: 2026-08-09T05:50:58.250Z
tags: Black-fingered Coral Crab, Cymo melanodactylus, Crabs, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/crustaceans/crabs/black-fingered-coral-crab
---

# Black-fingered Coral Crab (*Cymo melanodactylus*)

## Quick facts

- **Group:** Crabs (*Brachyura*)
- **Size:** up to 1.5 cm
- **Depth:** 1-20 m
- **Diet:** Detritivore
- **Activity:** Cathemeral
- **Rarity:** Common
- **Habitat:** Between the branches of Acropora and Pocillopora
- **Reproduction:** Brooder, Gonochoric

## How to recognise it

- small hairy crab with distinctly black claw tips
- shell covered in short bristles that collect sediment
- deep between coral branches, close to the base
- width up to 1.5 cm

A small bristly crab, about 1.5 cm (0.6 in), with black claw tips and a shell covered in short hairs that trap sediment until the animal matches the coral base it sits on. It lives deeper in the colony than the guard crabs, close to the branch bases where light does not reach.

Its standing is more ambiguous than that of the guard crabs it shares corals with. It takes mucus and tissue from the host and does not defend the colony, and where numbers build up on a stressed coral the crabs feed on the dying tissue directly - which has led to arguments about whether they cause damage or simply follow it. A healthy colony carries a few and is none the worse; a bleaching one can carry many. Either way they are among the most abundant animals inside branching corals, and a torch shone into a colony usually catches one moving.

## Also known as

- **English:** Black-fingered Coral Clinger
- **French:** Crabe corail à doigts noirs
- **Japanese:** キモガニ, キモガニ／サイモガニ, サイモガニ
- **Chinese:** 黑指波紋蟹
- **Russian:** Кримо чернопалый

## Scientific synonyms

- *Cancer (Cymo) meladactylus* De Haan, 1833
- *Cymo melanodactylus savaiiensis* Ward, 1939
- *Cymo melanodactylus var. purus* Chen, 1933

## Range

Comoros, East China Sea, Indian Ocean, Madagascar, Mozambique Channel, New Caledonian Exclusive Economic Zone, South Pacific Ocean

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*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/crustaceans/crabs/black-fingered-coral-crab)*
*Updated: August 9, 2026*