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Leaf Sheep

The leaf sheep is one of few animals that can perform photosynthesis!

 

Nicknamed for its sheep-like appearance and grazing habits, the leaf sheep is a sea slug found across tropical coral reefs in the eastern Indian and western Pacific oceans. They have two dark eyes and are covered in cerata, horn-like projections that actually help them breathe. Their heads are topped with two rhinophores, which act as scent and taste receptors. The leaf sheep spends its life on Avrainvillea, a type of algae that grows in fine silt or sand. They not only live on these algae but feed on it as well! 

Amazingly, the leaf sheep is one of few animals that can perform photosynthesis. They graze on the algae and suck up the chloroplasts, storing them within the tissues of their cerata in a process called kleptoplasty. The chloroplasts provide more than just nutrition, however. They also provide protection, giving the leaf sheep its striking green color and chemical defenses against predators. 

 

 

Like many small marine invertebrates, little is known about the conservation status of the leaf sheep. However, as with many ocean species, the primary threats to their future may be climate change and habitat loss. With intensified storms and warming oceans, we risk the loss of critical reefs and nearby algae that the leaf sheep relies on for survival. In fact, a study on a relative of the leaf sheep, the sea hare (Stylocheilus striatus), showed that these animals can experience lower foraging success and slower movement when exposed to increased ocean acidification and warming. 

 

 

Taking steps to tackle the climate crisis — like stopping the expansion of offshore drilling — can address the acceleration of warming ocean temperatures that degrade coral habitats and threaten the future of animals like the leaf sheep. Learn more about how Oceana campaigns to protect our climate here.

 

 

  • Associates, Sunderland, Massachusetts. xix + 936 pp. ISBN 0–87893–097–3. $109.95(cloth). 
  • Christa G, Gould SB, Franken J, Vleugels M, Karmeinski D, Händeler K, Martin WF, & Wägele H. (2014) Functional kleptoplasty in a limapontioidean genus: phylogeny, food preferences and photosynthesis in Costasiella, with a focus on C. ocellifera (Gastropoda: Sacoglossa). Journal of Molluscan Studies, 80: 499-507. https://doi.org/10.1093/mollus/eyu026 
  • Hay ME, Dufy JE, Paul VJ, Renaud PE, and Fenical W. (1990) Specialist herbivores reduce their susceptibility to predation by feeding on the chemically defended seaweed Avrainvillea longicaulis. Limnology and Oceanography, 35: 1734-1743. https://doi.org/10.4319/lo.1990.35.8.1734 
  • Horwitz R, Norin T, Watson SA. et al. (2020)  Near-future ocean warming and acidification alter foraging behaviour, locomotion, and metabolic rate in a keystone marine mollusc. Sci Rep 10: 5461. https://doi.org/10.1038/s41598-020-62304 
  • NOAA: Coral Reef Information System 
  • NOAA: Increase Resilience to Climate Change 
  • Rumpho ME, Pelletreau KN, Moustafa A, Bhattacharya D. The making of a photosynthetic animal. J Exp Biol. 2011 Jan 15;214(Pt 2):303-11. doi: 10.1242/jeb.046540. 
  • Wertz A, Rössler W, Obermayer, M. et al. (2006) Functional neuroanatomy of the rhinophore of Aplysia punctata. Front Zool 3:6. https://doi.org/10.1186/1742-9994-3-6 
  • Yonow N. (2015) Sea Slugs: Unexpected Biodiversity and Distribution. 10.1007/978-3-662-45201-1_30. 

 

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