The leaf sheep, or Costasiella kuroshimae, is capturing attention as a top contender for the 2026 Invertebrate of the Year. This tiny sea slug, often compared to a grain of rice, displays an adaptation rarely seen in the animal kingdom. Through a process known as kleptoplasty, the creature consumes algae and stores the chloroplasts within its own tissues. These structures then act as biological solar panels, allowing the slug to generate energy directly from the sun.
Found in the tropical waters near Japan, Indonesia, and the Philippines, the leaf sheep lives and feeds on Avrainvillea algae. Its physical appearance is striking, featuring vivid green branches known as cerata, often tipped with white or purple. These structures serve as both solar power stations and chemical defenses against predators. The animal navigates its environment using two ear-like rhinophores, which function as sophisticated sensory and taste receptors to locate its food source.
Although scientists first described the species in 1993, modern macro photography has propelled the leaf sheep into the public eye. Its resemblance to popular cultural icons, including various animated creatures, has made it a favorite among global audiences. As the 2026 voting period for Invertebrate of the Year approaches, this solar-powered mollusk remains a clear frontrunner due to its unique biological makeup and distinct aesthetic profile.