---
title: Three-lobed Elysia (Elysia trilobata)
scientific_name: Elysia trilobata
common_name: Three-lobed Elysia
taxon: Sap-sucking slugs
published: 2026-08-07T16:29:44.161Z
updated: 2026-08-07T21:30:28.597Z
tags: Three-lobed Elysia, Elysia trilobata, Sap-sucking slugs, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/molluscs/sap-sucking-slugs/three-lobed-elysia
---

# Three-lobed Elysia (*Elysia trilobata*)

## Quick facts

- **Group:** Sap-sucking slugs (*Sacoglossa*)
- **Size:** up to 3 cm
- **Depth:** 1-15 m
- **Diet:** Herbivore
- **Activity:** Diurnal
- **Rarity:** Very Rare
- **Habitat:** Green algae on sheltered reef
- **Reproduction:** Egg layer, Simultaneous hermaphrodite

## How to recognise it

- side flaps divided into distinct lobes rather than running straight
- green body with pale margins
- small, up to 3 cm
- on green algae in sheltered water

A small green sacoglossan of about 3 cm (1.2 in) whose side flaps are divided into distinct lobes instead of running as a straight sheet, which is the character behind the name and the one thing that separates it from the plainer green species sharing the same weed.

Beyond the shape almost nothing is on record. Worldwide there are only a handful of documented sightings, one of which comes from this coast, so anything written about its habits is inference from the family rather than observation of the animal: sacoglossans pierce algal cells with a single-toothed radula, drain them and keep the chloroplasts alive in their own tissues, and this one presumably does the same. A photograph of it with a date, a depth and the alga it was sitting on would add meaningfully to what is known, which is not something that can be said of many animals in this catalogue.

## Also known as

- **Russian:** Элизия трёхлопастная

---

*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/molluscs/sap-sucking-slugs/three-lobed-elysia)*
*Updated: August 7, 2026*