---
title: Wettstein's Cup Coral (Rhizopsammia wettsteini)
scientific_name: Rhizopsammia wettsteini
common_name: Wettstein's Cup Coral
taxon: Hard corals
published: 2026-07-26T12:41:46.627Z
updated: 2026-08-14T11:57:50.851Z
tags: Wettstein's Cup Coral, Rhizopsammia wettsteini, Hard corals, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/stinging/hard-corals/wettsteins-cup-coral
---

# Wettstein's Cup Coral (*Rhizopsammia wettsteini*)

## Quick facts

- **Group:** Hard corals (*Scleractinia*)
- **Size:** 1 - 3 cm
- **Depth:** 1-40 m
- **Diet:** Planktivore
- **Activity:** Nocturnal
- **Rarity:** Uncommon
- **Habitat:** Dark crevices, cave ceilings, and overhangs on coral reefs
- **Endemic:** Endemic to the Red Sea
- **CITES:** Appendix II

## How to recognise it

- solitary, glowing polyp (appears as)
- semi-transparent yellow tentacles
- tentacles with tiny white specks
- neon-yellow bloom

Rhizopsammia wettsteini is a colonial cup coral, though it frequently appears on the reef as distinct, usually solitary polyps. Individual polyps typically measure between 1 and 2 cm (0.4-0.8 in) in diameter. The corallite structure is a solid, opaque yellow, while its semi-transparent tentacles are a vibrant neon-yellow, heavily dotted with tiny white specks. These specks are concentrated batteries of stinging cells (nematocysts). As an azooxanthellate species, it lacks symbiotic algae and does not require sunlight for energy.

This coral inhabits the darkest recesses of reef environments, including the ceilings of caves, deep crevices, and shaded overhangs. It is typically found at depths ranging from 5 to 40 meters (16-130 feet). The coral actively extends its tentacles, particularly during periods of darkness or at night, to capture zooplankton from the water column. Rhizopsammia wettsteini is endemic to the Red Sea, where it is adapted to the region's highly saline conditions, and is distinguished from the closely related Indo-Pacific species Rhizopsammia verrilli.

## Also known as

- **Russian:** Коралл Веттштейна (или Желтый пещерный коралл)

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*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/stinging/hard-corals/wettsteins-cup-coral)*
*Updated: August 14, 2026*