---
title: Magnificent Sea Anemone (Radianthus magnifica)
scientific_name: Radianthus magnifica
common_name: Magnificent Sea Anemone
taxon: Sea anemones
published: 2026-08-08T15:47:14.088Z
updated: 2026-08-08T18:36:26.107Z
tags: Magnificent Sea Anemone, Radianthus magnifica, Sea anemones, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/stinging/sea-anemones/magnificent-sea-anemone
---

# Magnificent Sea Anemone (*Radianthus magnifica*)

## Quick facts

- **Group:** Sea anemones (*Actiniaria*)
- **Size:** up to 100 cm across
- **Depth:** 1-25 m
- **Diet:** Carnivore
- **Activity:** Diurnal
- **Rarity:** Uncommon
- **Habitat:** Exposed reef tops and current-swept coral heads
- **Reproduction:** Broadcast spawner, Gonochoric
- **Hazard:** Venomous

## How to recognise it

- very large disc, often a metre across, sitting fully in the open
- column brightly coloured - blue, green, red or purple
- long tentacles with slightly swollen tips, evenly spread
- column visible below the crown, not hidden in a crevice

The largest anemone on the reef and the one that sits in plain view: a disc reaching a metre (39 in) draped over the top of a coral head, with a column beneath it coloured blue, green, red or purple. Where other species hide the body and show only tentacles, this one is all body, and a big individual is visible from many metres away.

It takes exposed, current-swept positions on reef tops, which suits an animal that feeds on plankton and relies on symbiotic algae for much of its energy. Several clownfish species use it, and a large anemone commonly carries a whole family group plus damselfishes and shrimp. When disturbed it can pull the entire crown inward and become a coloured ball in seconds. The species has just been moved out of Heteractis into the genus Radianthus, so most books and dive guides still list it under the old name - both refer to the same animal.

## Also known as

- **Russian:** Великолепная актиния

## Scientific synonyms

- *Actinia magnifica* Quoy & Gaimard, 1833
- *Antheopsis ritteri* Kwietniewski
- *Corynactis magnifica* (Quoy & Gaimard, 1833)
- *Helianthopsis mabrucki* Carlgren, 1900
- *Helianthopsis ritteri* Kwietniewski, 1898
- *Heteractis magnifica* (Quoy & Gaimard, 1833)
- *Heteractis ritteri* (Kwietniewski, 1897)
- *Radianthus mabrucki* (Carlgren, 1900)
- *Radianthus paumotensis* (Couthouy)
- *Radianthus ritteri* (Kwietniewski, 1897)
- *Ropalactis magnifica* (Quoy & Gaimard, 1833)

## Range

Andaman Sea, Malaysia, Singapore

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*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/stinging/sea-anemones/magnificent-sea-anemone)*
*Updated: August 8, 2026*