---
title: Button Polyp (Zoanthus sansibaricus)
scientific_name: Zoanthus sansibaricus
common_name: Button Polyp
taxon: Zoanthids
published: 2026-08-10T20:57:59.065Z
updated: 2026-08-10T21:09:25.071Z
tags: Button Polyp, Zoanthus sansibaricus, Zoanthids, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/stinging/zoanthids/button-polyp
---

# Button Polyp (*Zoanthus sansibaricus*)

## Quick facts

- **Group:** Zoanthids (*Zoantharia*)
- **Size:** polyps to 1 cm, colonies to 1 m across
- **Depth:** 0-12 m
- **Diet:** Filter feeder
- **Activity:** Diurnal
- **Rarity:** Common
- **Habitat:** Shallow reef flats and rock, often where the surge is strong
- **Reproduction:** Broadcast spawner, Budding, Gonochoric
- **Hazard:** Poisonous

## How to recognise it

- dense carpet of small button-like polyps touching one another
- green, brown or blue-green discs with a contrasting mouth
- no sand grains in the body wall, so the surface looks smooth
- reef flats in shallow, surgy water

A dense carpet of small polyps pressed against one another like buttons on a cushion, green through brown to blue-green, each with a contrasting slit of a mouth at the center. Unlike the sand-stiffened zoanthids next to them on the same rock, these have smooth body walls, and the colony feels soft rather than gritty.

They hold ground in the surgiest, brightest water on the reef flat, where corals are broken and macroalgae are grazed off. Growth is by budding along the shared base, so a colony spreads outward as a widening mat and can cover a square meter of rock with what is, genetically, one animal repeated a thousand times.

Aquarium keepers know them better than divers do: these are the reef tank trade's "zoas", sold in a hundred color morphs with names to match. What the trade rarely mentions is the palytoxin the family can carry, which is why the same species is both a beginner's coral and a recurring case in poison-center reports.

## Also known as

- **English:** Violet Zoanthids
- **Portuguese:** Botão-do-mar-multicolorido
- **Japanese:** キクマメスナギンチャク
- **Russian:** Зоантус занзибарский

## Scientific synonyms

- *Zoanthus cavernarum* Pax & Müller, 1957
- *Zoanthus cyanoides* Pax & Müller, 1957
- *Zoanthus erythrochloros* Pax & Müller, 1957
- *Zoanthus gnophodes* Pax & Müller, 1957
- *Zoanthus zansibaricus* Carlgren, 1900

## Range

Indian Ocean, Japan, Mozambique, South Africa, Tanzania

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*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/stinging/zoanthids/button-polyp)*
*Updated: August 10, 2026*