Black-banded sea slug
Cyerce nigricans
Leaf sheep
Costasiella kuroshimae
About
The leaf sheep is a tiny sea slug that runs partly on sunlight. It steals chloroplasts from the algae it eats and keeps them working inside its own body, so it can turn light into food like a plant.
How to tell it apart
Other small sea slugs can look similar at a glance. The pair of ear-like rhinophores paired with the two dark eyes just below them is the giveaway sheep face that sets this species apart.
Appearance
Rows of leaf-shaped bumps called cerata cover its back, giving it a green, plant-like look. Two rhinophores rise from its head like a pair of sheep's ears, and two small dark eyes sit below them, giving the face its sheep-like look.
Did you know?
The leaf sheep was voted the 2026 winner of The Guardian's invertebrate of the year competition.
Log it in Into the Blue
Describe what you saw and we name it, then keep every species you find in your Oceandex.
