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6 unknown facts about the photosynthesis performing Leaf Sheep: the solar-powered sea slug

Source: Flickr / Randi Ang

These adorable little creatures look like a farm animal, act like a plant, and live in the sea—but much about them still remains a mystery.

Leaf sheep: the cutest little solar-powered sea slug

Meet the Costasiella kuroshimae (or ‘Leaf Sheep’ for short). These adorable little sea slugs feeds on algae. What’s interesting about these tiny animals—which can grow up to 5mm in length and are found near Japan, Indonesia and the Philippines—is that they are one of the few sea creatures in the world that can perform photosynthesis. When these cute little creatures eat algae, they suck out the chloroplasts and incorporate them into their own bodies in a process called kleptoplasty. This process, which otherwise can only be performed by single-celled organisms, essentially makes them solar-powered slugs! Scroll down for photos and video of these delightful little animals— spotted on Facebook and UniGuide. — All photos courtesy of Randi Ang, whose work can be seen on Instagram and on Flickr.

Leaf sheep are actually a species of sea slug. A term used commonly to describe marine invertebrates, sea slugs resemble terrestrial slugs. However, they come in a wide variety of shapes and colors. Sea slugs are closely related to gastropods, such as sea snails and mollusks, with the main difference being that they don’t have shells. Along with leaf sheep, nudibranchs are another type of sea slug.
1. They’re neither leaves nor sheep. Leaf sheep are actually a species of sea slug. A term used commonly to describe marine invertebrates, sea slugs resemble terrestrial slugs. However, they come in a wide variety of shapes and colors. Sea slugs are closely related to gastropods, such as sea snails and mollusks, with the main difference being that they don’t have shells. Along with leaf sheep, nudibranchs are another type of sea slug. Source: Randi Ang
Leaf sheep have rhinophores on their heads that look like the ears of a sheep in perspective to their faces. They also resemble antennae on insects. The lead sheep’s rhinophores have fine hairs that sense chemicals in the water, enabling lead sheep and other sea slugs to find food sources.
2. What looks like sheep’s ears are actually scent and taste receptors. Leaf sheep have rhinophores on their heads that look like the ears of a sheep in perspective to their faces. They also resemble antennae on insects. The lead sheep’s rhinophores have fine hairs that sense chemicals in the water, enabling lead sheep and other sea slugs to find food sources. Source: Flickr/Randi Ang
Leaf sheep are only about a quarter of an inch, or a little over 5mm long. Yet, even at this size, their physical appearance is incredibly detailed. Some say they remind them of succulent plants such as aloe vera.
3. Leaf sheep are about the size of a grain of rice. Leaf sheep are only about a quarter of an inch, or a little over 5mm long. Yet, even at this size, their physical appearance is incredibly detailed. Some say they remind them of succulent plants such as aloe vera. Source: Flickr/Randi Ang
Leaf sheep’s scientific name, Costasiella kuroshimae, is a combination or Latin and Japanese. Costasiella indicates the genus name of all sea slugs belonging to the sacoglossa group. Kuroshima, in Japan, is where they were first found. They are also referred to as “sap-sucking sea slugs.”
4. Their scientific name is a combination of Latin and Japanese. Leaf sheep’s scientific name, Costasiella kuroshimae, is a combination or Latin and Japanese. Costasiella indicates the genus name of all sea slugs belonging to the sacoglossa group. Kuroshima, in Japan, is where they were first found. They are also referred to as “sap-sucking sea slugs.” Source: Flickr/Randi Ang
Although not plants, leaf sheep exhibit one key plant-like characteristic. They can perform the process of photosynthesis, which is the process by which plants can use sunlight to create energy from carbon dioxide and water. Leaf sheep’s primary diet is sea algae. When they consume it, they can suck the chloroplasts out of the algae, in a process called kleptoplasty. This process enables them to photosynthesise and it’s why leaf sheep glow, or are somewhat bioluminescent. Why leaf sheep and other sacoglossans have the ability to photosynthesise, when they also eat, is still something of a mystery. However, scientists believe it must have something to do with evolutionary survival.
5. Leaf sheep are among the few sea creatures who can photosynthesise. Although not plants, leaf sheep exhibit one key plant-like characteristic. They can perform the process of photosynthesis, which is the process by which plants can use sunlight to create energy from carbon dioxide and water. Leaf sheep’s primary diet is sea algae. When they consume it, they can suck the chloroplasts out of the algae, in a process called kleptoplasty. This process enables them to photosynthesise and it’s why leaf sheep glow, or are somewhat bioluminescent. Why leaf sheep and other sacoglossans have the ability to photosynthesise, when they also eat, is still something of a mystery. However, scientists believe it must have something to do with evolutionary survival. Source: Flickr/Randi Ang
While some scientists believe that kleptoplasty can add to longevity in sacoglossans, the truth is – nobody knows how long leaf sheep live. For a species discovered less than three decades ago, we still have much to learn.
6. We don’t know how long they live. While some scientists believe that kleptoplasty can add to longevity in sacoglossans, the truth is – nobody knows how long leaf sheep live. For a species discovered less than three decades ago, we still have much to learn. Source: Flickr/Randi Ang

Shaun the Sheep ~ This SUPER CUTE Sap sucking SEA SLUG is a REAL ANIMAL - Costasiella These Costasiella are my absolute favourite type of seaslug . Although not a nudibranch, no one can deny their cuteness. Those tiny close set eyes, little pink cheeks, large black tipped rhinophores and all that sparkly colourful cerata make them pretty damn amazing. And as if that wasn’t enough, these magical masters of nature eat so much algae, that they can actually use it themselves to photosynthesise! Solar powered slugs! Source: YouTube/David Palfrey
In the Sheepy Realm - The Costasiella Seaslug These cute Costasiella Sea Slugs ar tiny as ricecorns and live on leafy algaes...filmed in Bali Source: YouTube/Catrin Pichler

Want more Leaf Sheep?

Here are a couple places where you can see some fun, if not so scientific, depictions of leaf sheep:

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