---
title: Banded Sea Urchin (Echinothrix calamaris)
scientific_name: Echinothrix calamaris
common_name: Banded Sea Urchin
taxon: Sea urchin
published: 2024-01-03T05:34:59.421Z
updated: 2026-08-15T19:10:55.219Z
tags: Banded Sea Urchin, Echinothrix calamaris, Sea urchin, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/echinoderms/sea-urchin/banded-sea-urchin
---

# Banded Sea Urchin (*Echinothrix calamaris*)

## Quick facts

- **Group:** Sea urchin (*Echinoidea*)
- **Size:** up to 25 cm
- **Depth:** 1-70 m
- **Diet:** Herbivore
- **Activity:** Nocturnal
- **Rarity:** Common
- **Habitat:** Reef and rubble, wedged under ledges by day
- **Reproduction:** Broadcast spawner, Gonochoric
- **Hazard:** Dangerous, Venomous

## How to recognise it

- two kinds of spines: long banded black-and-white ones, and short fine dark ones between them
- dark test often visible through the spines, with a pale anal sac at the top
- shrimps and cardinalfish sheltering among the spines
- spines to 25 cm

Banded black and white spines up to twenty-five centimeters long, with a second set of much finer, darker ones packed between them - and that second set is the dangerous one. The long spines are blunt and mostly structural; the short fine ones are barbed and venomous, and they are what a hand actually meets.

The pale sac visible at the top between the spines is the anal sac, and it is often the easiest way to identify the species from above.

What lives in there is the other half of the card. A single urchin can shelter cardinalfish, shrimps, small crabs and juvenile fish, all of them keeping the spines between themselves and everything else, and rotating around the animal as a diver circles it. Some of those species live nowhere else. An urchin is not just an animal, it is an address.

By day it wedges under a ledge; at night it moves out to graze algae, and a reef flat that looked empty at sunset is covered in them by full dark.

## Also known as

- **English:** banded sea urchin, Double Spined Urchin, banded urchin, Double-spined sea urchin
- **French:** Oursin à doubles piquants
- **Italian:** Riccio diadema a bande
- **German:** Calamaris-Seeigel
- **Czech:** ježovka pruhovaná
- **Japanese:** トックリガンガゼモドキ
- **Chinese:** 環刺棘海膽
- **Russian:** Эхинотрикс кальмаровый
- **TH:** เม่นดาวหนามขาว, เม่นทะเลดำหนามสั้น

## Scientific synonyms

- *Astropyga calamaria* (Pallas, 1774)
- *Astropyga desorii* L. Agassiz in L. Agassiz & Desor, 1846
- *Cidaris calamaria* (Pallas, 1774)
- *Cidaris calamaris* (Pallas, 1774)
- *Cidarites calamaria* (Pallas, 1774)
- *Diadema calamare* (Pallas, 1774)
- *Diadema calamaria* (Pallas, 1774)
- *Diadema calamarium* (Pallas, 1774)
- *Diadema desori* (L. Agassiz in L. Agassiz & Desor, 1846)
- *Diadema frappieri* (Michelin, 1862)
- *Echinothrix aequalis* (Gray, 1855)
- *Echinothrix annellata* Peters, 1853
- *Echinothrix aperta* A. Agassiz, 1863
- *Echinothrix clavata* (Gray, 1855)
- *Echinothrix desori* (L. Agassiz in L. Agassiz & Desor, 1846)
- *Echinothrix desorii* (L. Agassiz in L. Agassiz & Desor, 1846)
- *Echinothrix scutata* A. Agassiz, 1863
- *Echinotrix calamaris* (Pallas, 1774)
- *Echinus calamaris* Pallas, 1774
- *Echinus calamarus* Pallas, 1774
- *Garelia aequalis* Gray, 1855
- *Garelia clavata* Gray, 1855
- *Savignya frappieri* Michelin, 1862

## Range

East Indies, Eastern Africa & Madagascar, Federal Republic of Somalia, Indian Ocean, Kenya, Madagascar, Maldives, Mozambique, Philippines, Red Sea, Republic of Mauritius, Seychelles, South Africa, South Andaman Islands, Tanzania

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*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/echinoderms/sea-urchin/banded-sea-urchin)*
*Updated: August 15, 2026*