---
title: Gosliner's Flatworm (Pseudoceros goslineri)
scientific_name: Pseudoceros goslineri
common_name: Gosliner's Flatworm
taxon: Flatworms
published: 2026-08-10T21:29:09.387Z
updated: 2026-08-10T22:07:38.594Z
tags: Gosliner's Flatworm, Pseudoceros goslineri, Flatworms, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/worms/flatworms/gosliners-flatworm
---

# Gosliner's Flatworm (*Pseudoceros goslineri*)

## Quick facts

- **Group:** Flatworms (*Pseudocerotidae*)
- **Size:** up to 7 cm
- **Depth:** 3-30 m
- **Diet:** Carnivore
- **Activity:** Nocturnal
- **Rarity:** Uncommon
- **Habitat:** Reef slopes, walls and overhangs
- **Reproduction:** Egg layer, Simultaneous hermaphrodite
- **Hazard:** Poisonous

## How to recognise it

- cream body mottled with orange over the middle
- purple to violet band at the margin
- up to 7 cm, broad and thin
- found on walls and under overhangs more than on open rubble

A broad cream sheet mottled with orange across the middle and edged in purple, up to 7 cm (2.8 in) long. The margin color is the quickest way to name it: several local flatworms are cream and orange, and almost none of them finish in violet.

Walls and overhangs suit it better than open rubble, and it is more often found upside down under a ledge than out on top of the reef. Sea squirts growing in the same shade are the usual prey, taken by everting the pharynx over them - the worm digests its meal outside its body and absorbs what is left.

The species is named after Terrence Gosliner, whose work on sea slugs and their relatives ran through the same waters and the same decades. The name arrived in 1994, which is recent for an animal this conspicuous, and a reminder of how much of this group was still being sorted out while people were already photographing it.

## Also known as

- **French:** Ver plat de Gosliner
- **Japanese:** ハナアカリニセツノヒラムシ
- **Chinese:** 嘉氏偽角扁蟲, 柯氏偽角扁蟲
- **Russian:** Плоский червь Гослинера

## Range

Australia, British Indian Ocean Territory, India, Indian Ocean, Indonesia, Maldives, Papua New Guinean Exclusive Economic Zone, Tanzania

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*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/worms/flatworms/gosliners-flatworm)*
*Updated: August 10, 2026*