It is a sheep! This is a cow! No, it is Costasiella kuroshimae (also known as “Leaf Sheep”). This lovely tiny sea slug, which resembles a cartoon sea sheep because to its beady eyes and cute appendages, feeds on algae – exactly like the real thing!
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They are one of the few marine organisms in the world capable of photosynthesis, which is what makes them so intriguing. They may grow up to 5 millimeters in length and can be found around Japan, Indonesia, and the Philippines (the others all belong to the sacoglossa sea slug clade).
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As these bizarre creatures consume algae, they absorb the chloroplasts into their body in a process known as kleptoplasty. This technique, which is otherwise exclusive to unicellular creatures, effectively transforms them into solar-powered slugs!
If this lovely little creature of the water has inspired you to see sea slugs in a new light, then check out this adorable ‘sea bunny’ sea slug to cap the deal
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Consider the Sacoglossa sea slug, also known as the “solar-powered sea slug” – or, when scientists are feeling unkind, the “sap-sucking sea slug.” Or we could call it the “self-decapitating sea slug that bears an uncanny resemblance to Shaun the Sheep” and still be entirely fair to this tiny creature, Costasiella kuroshimae.
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In fact, there are 284 recognized species of Sacoglossa sea slugs in temperate and tropical oceans across the world, but only C. kuroshimae resembles a cute cross between Shaun the Sheep and Medusa. It inhabits Southeast Asian seas.
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Shaun the Sheep is a cartoon character that appeared in “Farmageddon,” among other works. He is endearing. Nevertheless, let us return to the sea slugs.
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Some of the other Sacoglossans bore a superficial similarity to beloved sheep, whereas others resemble seaweed primarily, and this is no accident.
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Sacoglossans constitute what zoologists refer to as a “superorder” within the mollusk kingdom and may be divided into two primary types: those that maintain a shell like their cousin the snail and are essentially bivalve gastropods; and those that lost their shells during their evolution. The film “Shaun the Sheep” Sacoglossans are shell-less. These are the animals affectionately referred to as “sea sheep,” although they are not.
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These several Sacoglossan branches have a peculiar connection with algae in common.
In contrast to snails, which have a flexible band called a radula with thousands of microscopic teeth that scrape food particles from – you don’t want to know – Sacoglossans have only one row of microscopic teeth on their radula.
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Plasma is extracted from algal cells by the comparatively non-horrifying radula of “sap-sucking sea slugs.” The shelled Sacoglossans have a special preference for Caulerpa seaweed, which resembles a sea soybean plant.
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The sea slugs that feed on sap easily consume this plasma. This is not an uncommon occurrence. Sacoglossa without a shell have expanded their diet to include siphonalean and septate green algae.
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The other Sacoglossans that “filter out” chloroplasts from algae they feed, sequester the chloroplasts inside their own tissues, and employ these embezzled chloroplasts to perform the same thing the algae did with them – photosynthesize – set themselves apart from every other multicellular animal on earth.