What is a leaf sheep?

The leaf sheep (Costasiella kuroshimae) is a rice-sized sea slug found in the western Pacific and eastern Indian Ocean. It is notable for its ability to perform kleptoplasty, stealing chloroplasts from algae to partially generate energy from sunlight. These slugs use cerata for energy storage and camouflage, and rhinophores to sense their environment. As grazers of Avrainvillea sp. algae, they contribute to marine biodiversity and provide scientific insights into symbiosis and photosynthesis.

• The leaf sheep, scientifically known as Costasiella kuroshimae, is a tiny sea slug approximately the size of a grain of rice that inhabits shallow tropical waters in the eastern Indian Ocean and western Pacific, specifically including the Philippines, Indonesia, and Japan.
• Leaf sheep are among the few animals capable of partially harnessing photosynthesis through a process called kleptoplasty, where they steal chloroplasts from the algae they eat and store them in leafy branches on their backs called cerata.
• The species possesses specific anatomical adaptations: rhinophores act as chemical sensors to help the slug find food and detect surroundings, while the green cerata provide camouflage against algae and may contain chemical defenses.
• Leaf sheep are simultaneous hermaphrodites that require a partner to reproduce, laying their eggs in spiral ribbons on algae. Ecologically, they serve as grazers of Avrainvillea sp. algae, helping to maintain balance in seagrass habitats and shallow reefs.

APA

WWF International (n.d.). What is a leaf sheep? https://www.worldwildlife.org/resources/facts/what-is-a-leaf-sheep/

Chicago

WWF International. What is a leaf sheep? n.d. https://www.worldwildlife.org/resources/facts/what-is-a-leaf-sheep/.

Wikipedia

{{cite report |author=WWF International |title=What is a leaf sheep? |url=https://www.worldwildlife.org/resources/facts/what-is-a-leaf-sheep/ |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{wwfinternationalndwhat, author = {{WWF International}}, title = {{What is a leaf sheep?}}, institution = {WWF International}, url = {https://www.worldwildlife.org/resources/facts/what-is-a-leaf-sheep/}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }