---
title: Gold-speckled Flatworm (Thysanozoon nigropapillosum)
scientific_name: Thysanozoon nigropapillosum
common_name: Gold-speckled Flatworm
taxon: Flatworms
published: 2026-08-10T21:29:09.418Z
updated: 2026-08-10T21:36:05.009Z
tags: Gold-speckled Flatworm, Thysanozoon nigropapillosum, Flatworms, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/worms/flatworms/gold-speckled-flatworm
---

# Gold-speckled Flatworm (*Thysanozoon nigropapillosum*)

## Quick facts

- **Group:** Flatworms (*Pseudocerotidae*)
- **Size:** up to 3 cm
- **Depth:** 1-25 m
- **Diet:** Carnivore
- **Activity:** Diurnal
- **Rarity:** Common
- **Habitat:** Reef flats and slopes, frequently swimming in midwater
- **Reproduction:** Egg layer, Simultaneous hermaphrodite
- **Hazard:** Poisonous

## How to recognise it

- black back covered in papillae with bright yellow tips
- brilliant white margin, undulating as it swims
- up to 3 cm, often seen swimming clear of the bottom
- underside plain and pale

Black, covered in soft papillae tipped with bright yellow, and finished with a brilliant white margin, up to 3 cm (1.2 in) long. Of all the flatworms here this is the one divers remember, because it spends so much time off the bottom: it swims freely in midwater with slow waves running along both edges, looking like a piece of animated silk.

The papillae are extensions of the gut, and they add surface where a thicker animal would need lungs or gills. Everything about the body plan follows from having no way to move oxygen internally - stay flat, stay thin, and let physics do the delivery.

Swimming in the open in daylight is a bold habit for something soft and edible, and it works for the same reason the colors do. The skin is toxic, the pattern is memorable, and a fish that has tried one does not repeat it. The species is also one of the few flatworms common enough that a diver can expect to meet it rather than hope to.

## Also known as

- **Russian:** Плоский червь золотистокрапчатый

## Scientific synonyms

- *Acanthozoon nigropapillosum* Hyman, 1959
- *Acanthozoon nigropapillosus* Hyman, 1959

## Range

Singapore

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