---
title: Ornate Armina (Dermatobranchus ornatus)
scientific_name: Dermatobranchus ornatus
common_name: Ornate Armina
taxon: Nudibranch
published: 2026-07-03T12:49:04.613Z
updated: 2026-08-28T20:54:28.816Z
tags: Ornate Armina, Dermatobranchus ornatus, Nudibranch, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/molluscs/nudibranch/ornate-armina
---

# Ornate Armina (*Dermatobranchus ornatus*)

## Quick facts

- **Group:** Nudibranch (*Nudibranchia*)
- **Size:** up to 8 cm
- **Depth:** 1-30 m
- **Diet:** Carnivore
- **Activity:** Nocturnal
- **Rarity:** Uncommon
- **Habitat:** Sand and rubble near soft corals and sea pens
- **Reproduction:** Egg layer, Simultaneous hermaphrodite
- **Hazard:** Poisonous

## How to recognise it

- oval body with fine longitudinal ridges running the whole length
- white with black lines along the ridges and an orange margin
- no gills visible on the back - they sit under the mantle skirt
- length up to 8 cm

A ribbed white and black slug with an orange edge, working sand and rubble beside soft coral. Eight centimeters (3 in), and a different animal from the chromodorids that dominate this section.

The arminids eat cnidarians rather than sponges - soft corals, sea pens, the colonial animals that other predators leave alone because of their stinging cells and their chemistry. That is a harder living, and it is done by grazing polyp by polyp, usually at night.

The ridges are the family's signature. Instead of a soft frilly back it carries a firm, longitudinally ribbed mantle with the gills hidden underneath the skirt, along the sides - which is why nothing shows on top.

It spends the day buried in sand and comes out after dark, so almost every photograph of one is a night dive photograph. Look at the base of soft corals with a torch and check anything ribbed that is moving very slowly.

## Also known as

- **English:** Ornate Pinstripe
- **French:** Dermatobranche orné
- **Japanese:** ハナオトメウミウシ
- **Chinese:** 華麗皮鰓海蛞蝓, 裝飾片鰓海蛞蝓

## Scientific synonyms

- *Pleuroleura ornata* Bergh, 1874

## Range

South Africa

---

*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/molluscs/nudibranch/ornate-armina)*
*Updated: August 28, 2026*