---
title: Tsuruga Headshield Slug (Mariaglaja tsurugensis)
scientific_name: Mariaglaja tsurugensis
common_name: Tsuruga Headshield Slug
taxon: Opisthobranchia
published: 2024-05-20T15:55:22.765Z
updated: 2026-08-15T20:22:57.155Z
tags: Tsuruga Headshield Slug, Mariaglaja tsurugensis, Opisthobranchia, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/molluscs/opisthobranchia/tsuruga-headshield-slug
---

# Tsuruga Headshield Slug (*Mariaglaja tsurugensis*)

## Quick facts

- **Group:** Opisthobranchia (*Opisthobranchia*)
- **Size:** up to 2 cm
- **Depth:** 0-20 m
- **Diet:** Carnivore
- **Activity:** Diurnal
- **Rarity:** Uncommon
- **Habitat:** Sand and silty rubble in shallow water
- **Reproduction:** Egg layer, Simultaneous hermaphrodite

## How to recognise it

- small dark slug with fine pale speckling and a pale margin
- flattened head shield, no tentacles
- tail lobes short and nearly equal, unlike its long-tailed relatives
- length up to 2 cm

Two centimeters (0.8 in) of dark speckled slug plowing the surface of shallow sand, with a head shield and almost no tail to speak of.

Until recently it was a *Chelidonura* like the rest of them. The genus was split in 2019 on the basis of anatomy and genetics, and a group of short-tailed species moved to *Mariaglaja* - which is why almost every photograph of this animal online is filed under the old name, and why field guides printed before then will not have it.

That kind of change is routine in sea slugs, and it is the reason a catalogue has to carry the scientific name rather than rely on a common one: the animal has not changed, the shelf it sits on has.

Biologically it is a headshield slug like its larger relative: it hunts small flatworms and other soft prey below the sand surface, follows their trails, and swallows them whole. It is a simultaneous hermaphrodite and lays a coiled egg ribbon in the sediment.

## Also known as

- **English:** Variable Swallowtail
- **Hebrew:** דו-זנבית מנומרת, דו-זנבית סנדרנה
- **Japanese:** ミョウジンツバメガイ
- **Chinese:** 敦賀美尾海蛞蝓

## Scientific synonyms

- *Chelidonura babai* Gosliner, 1988
- *Chelidonura sandrana* Rudman, 1973
- *Chelidonura tsurugensis* Baba & Abe, 1959
- *Mariaglaja sandrana* (Rudman, 1973)

## Range

Mozambique, South Africa

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*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/molluscs/opisthobranchia/tsuruga-headshield-slug)*
*Updated: August 15, 2026*