#kleptoplasty

[biologist4ever]

Not a Plant, Not a Sheep… It's a Photosynthesizing Slug!

But it’s dressed like a plant… and powers itself like one, too.

Meet the Leaf Sheep (Costasiella kuroshimae) — one of the smallest and strangest marvels of the sea.

Barely the size of a grain of rice, this creature has black ear-like tentacles, bead-black eyes, and a back covered in tiny green “leaves.”

Those aren’t leaves at all — they’re cerata, filled with stolen chloroplasts from the algae it eats.

Through a process called kleptoplasty, the Leaf Sheep turns sunlight into energy, making it one of the few animals on Earth to photosynthesize.

Its leafy camouflage hides it among seaweed while its stolen solar cells fuel its day.

Drifting through warm Indo-Pacific reefs, it grazes on algae like a tiny sheep of the sea… except this one runs on sunlight.

[artifacts-and-arthropods]

Elysia viridis: this sea slug is one of the few known animals that can engage in photosynthesis, which allows it to survive without food for months at a time

Elysia viridis is a sacoglossan sea slug with an unusual ability -- it can "steal" the photosynthesizing organelles from algae and then incorporate those chloroplasts into its own body, where they continue to convert sunlight into energy. This process produces nutrients that supplement the sea slug's diet.

Above: Elysia viridis

The acquired chloroplasts are often referred to as kleptoplasts, which means "stolen plastids." Their photosynthesizing ability allows the sea slug to survive with limited food (or no food at all) for months at a time.

As this article explains:

In sacoglossan sea slugs, kleptoplasts are harboured in cells of the digestive diverticula, enabling their animal host to survive photo-autotrophically for periods ranging from days to up to one year after being "stolen" from algal cells.

Due to these remarkable features, sacoglossan sea slugs have frequently been termed "leaves that crawl" or "solar-powered sea slugs."

Elysia viridis can have a green or reddish-brown appearance, depending on the amount of light that it receives and the color of the algae that it consumes. Its body is also covered in glittering, iridescent flecks of blue and green.

Above: the photo at the top shows Elysia viridis with its parapodial lobes folded over its body, while the photo at the bottom shows the same species with the lobes completely unfurled

The sea slug's body is flanked by two flat, wing-like lobes that can fold inward or unfurl, allowing the animal to regulate its light exposure. When these flaps are stretched open, the sea slug looks remarkably similar to a leaf; its body has a flat, wavy appearance, and its digestive glands are clearly visible just beneath the surface of the skin, mimicking the veins of a leaf.

Above: Elysia viridis as a baby

Several other sea slugs are also known to engage in photosynthesis, but this phenomenon is still remarkably rare among animals at large. Most of the animals that do photosynthesize are marine invertebrates, including sacoglossan sea slugs and certain nudibranchs.

Above: Elysia chlorotica, another photosynthizing sea slug from the same genus

Sources & More Info:

Journal of Experimental Botany: Crawling Leaves: Photosynthesis in Sacoglossan Sea Slugs

Senckenberg Society for Nature: Identification and Biology of Elysia viridis

Nature New Biology: Persistence of Functional Chloroplasts in Elysia viridis

PLOS Biology: Kleptoplasty: Getting Away with Stolen Chloroplasts

University of Southern Denmark: Functional Chloroplasts Inside Animal Cells (PDF)

Journal of Experimental Biology: The Making of a Photosynthetic Animal

[sitting-on-me-bum]

“PhotosyntheSlug”

“The cactus sea-slug (Sacoproteus smaragdinus) is a herbivorous sea slug measuring up to 8 cm in length. Despite its size, it is rarely seen as its appearance is almost identical to the Caulerpa cactoides alga it feeds on. Not only do the cerata – green globules on its back – provide excellent camouflage, they also photosynthesize. The green hues are chloroplasts retained in the slug's digestive system, a unique symbiotic relationship known as kleptoplasty. The cells continue to photosynthesize, giving its host energy. The cactus sea slug is one of rather few multicellular animals multicellular animal to do so, giving it the nickname “’solar-powered sea slug.’”

Alison McNeice

Tasmania’s Science Photography Prize

[hurdy-girly]

oh that's YOU with the leaf sheep sideblog!!

I enjoy sea slugs on principle (because Good) but i don't know anything about them, what are some of your favourite sea slug facts? :D

HI HELLO I LOVE THIS QUESTION

Sorry for the late reply!! I was writing a very in depth reply to this right after you sent it but tumblr deleted it randomly and I lost my steam so I’m gonna try again lol

The main thing about sea slugs that got me really interested is called Kleptoplasty. The main slug that is talked about in regard to this is Costasiella kuroshimae, more commonly known as the leaf sheep. However, many other species in their clade (called sacoglossa) also utilize it. Kleptoplasty is a process where an organism consumes a plant and then siphons out the chloroplasts from its cells. They store the chloroplasts in themselves and use them to generate energy. The only other animals to evolve this practice are two kinds of marine flatworms, but I’m not very familiar with them. As far as I know sea slugs outside of sacoglossa don’t use Kleptoplasty, though there is another kind (Pteraeolidia ianthina) that farms microscopic plants in itself to get the energy.

Another sea slug practice that got me interested early on is cnidocytes siphoning. Cnidocytes, also known as nematocysts, are the stinging cells that a lot of sea anemones and hydrozoans have. These cells are basically little stingers that hang out and stab whatever touches them before releasing a toxin. Most animals will avoid these, but a lot of sea slugs have learned to eat them. They don’t just digest them, though. They will take these cells and, similarly to the chloroplasts, will remove them from the other food and utilize them themselves. They keep these in cnidosacs, which from what I can tell are specific to aeolid sea slugs. The most discussed species that does this is Glaucus atlanticus. They look really cool and float in the water. Touching them is really dangerous, especially because they concentrate the venom in their cnidosacs and make it more deadly than it originally was in the original species.

I guess the main thing that drew me to sea slugs is the fact that so many of them I criminals, looking at it. They’re fascinating and gorgeous as well! I’ve been crocheting a bunch of them since January. I think I’ve made over twenty by now? I lost count. Some of them are based off of real slugs and some aren’t. My first ones were all dorid, meaning they had little gill plumes on their backs, but I just started making an aeolid one (the ones with all the cerata ((the little horn like outgrowths)) on their backs).

One last thing: these guys are TINY. The pictures make them seem much bigger but do not be mistaken, these guys are SMALL. Most of them are like. Rice grain size. (EDIT: I was misremembering, they’re a bit bigger than that. Most are a centimeter or two long.) Some are bigger, the biggest (Aplysia vaccaria) is like 39 inches, but most are SO SMALL AND I LOVE THEM. I have not seen one in person yet but I need to within this year or I will spontaneously combust.

Thank you for the ask!!! Sorry again it took so long to reply, but it was really fun to look back at the stuff that got me into them. I think I’ll finish this off with some more pictures of various slugs that I love :3

[adiaryofnonsense]

Happy MerMay #11 (I’m pretty sure)

I know I haven’t really been posting… I don’t really have an excuse I’m just really bad at this lol

Elysia Crispata also known as the lettuce sea slug! (And yes, its scientific name is pronounced Crisp-ata. Like crispy lettuce! It’s adorable!) she is the third installment of my sacoglassan sea slug series.

Sacoglassan sea slug science sss-below (I couldn’t come up with another S word)

Elysia Crispata is unusually large compared to other Sacoglassan sea slugs (reaching and max size of 15cm or almost 6in while other slugs like E. Chlorotica only gets to a max of around 60mm or 2.4 inches) along with its unusual size Elysia Crispata also eats and unusually wide variety of food. Most Sacoglassans only eat one type of algae, they typically live in and on their chosen food source, then they usually take on traits from their specific algae. Elysia Crispata, however, can eat a wide variety of algae, and they are often found on bare rock and coral by divers (that’s why I gave her the skateboard :))

What makes their ability to eat a versatile food source so interesting comes back around to kleptoplasty (which I talked about a little in my post for Elysia Chloritica) Kleptoplasty is an ability solely belonging to sacoglassan sea slugs—it allows them to uses photosynthesis.

Sacoglassan sea slugs are also known as sap-sucking or solar-powered sea slugs because the slugs eat the cellular content of algae like sap, however, the chloroplasts do not get digested. Somehow the sea slugs have managed to figure out how to host and use the chloroplasts for themselves!! They steal (klepto-) photosynthesis (-plasty)!!! It’s so cool! They are so cool! I love them!!!!

[todropscience]

SELF-DECAPITATING BEHAVIOR SEEN IN SEA SLUGS

​The body they leave behind dies.

Autotomy, the voluntary shedding of a body part, is fairly widespread in the animal kingdom, and is generally followed by the regeneration of shed terminal body parts, but now, two japan researches have found a extrem case of autotomy in photosynthetic sea slugs.

Under lab conditions, two species of Elysia sea slugs - know by their capacity to use chloroplasts from algal food into their cells to utilise for photosynthesis- were infected with parasites, after that, sea slugs self-decapitated, suggesting they do it to get rid of parasites.

According to researchers, the head, separated from body and organs, moves on its own immediately after the separation (as the GIF shown). Within days, the wound at the back of the head is closed, while the head feeds on algaes. At the first week the head starte the body regeneration, and by the third week, regeneration is completed.

- Head and the body of Elysia cf. marginata, a day after autotomy. The shed body is much heavier (>80% of the total weight) than the head. Photo by Sayaka Mitoh.

Researchers Believe the slugs may use the photosynthetic ability of chloroplasts they incorporate from the algae in their diet, a proccess called kleptoplasty, to survive long enough for regeneration.

These findings in sea slugs represent a new type of autotomy in which animals with complex body plans shed most of their body.

Reference (Open Access): Mitoh and Yusa. 2021. Extreme autotomy and regeneration of the whole body in photosynthetic sea slugs. Current Biology.

Gif: Movement of Elysia cf. marginata  after induced autotomy.

[bpod-bpod]

Head Over Hearts

Lizards shedding and re-growing their tails are probably the best-known examples of impressive regeneration in animals, but other species take autotomy, the voluntary loss of body parts, to an extraordinary extreme. Sea slugs Elysia cf. marginata (shown here) and E. atroviridis can separate their heads from the rest of their body, including their heart, and not only survive, but regenerate a complete body from the head section: feeding within hours, regrowing a heart within a week, and fully regenerating around three weeks after the break. Their diet may hold the key to surviving without major internal organs, as the sea slugs perform kleptoplasty, taking up chloroplasts from the algae they eat into their own tissues, to provide them with energy through photosynthesis. Why they undergo this traumatic process is still unclear, but it could be a means of shedding internal parasites – a radical response that reveals new champions of regeneration.

Written by Emmanuelle Briolat

Video by Sayaka Mitoh

Nara Women’s University, Kitauoya-nishi, Nara, Japan

Video copyright held by the original authors

Research by Sayaka Mitoh and Yoichi Yusa published in Current Biology, March 2021

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[molluscfacts]

The Lettuce Slug

Lettuce sea slugs (Elysia crispata) are a commonly found in protected nearshore Floridian waters where green macroalgae proliferates. They belong to a clan of sea slugs, the sacoglossans, that are characterized by their 'sap-sucking' feeding habits of algae. These slugs slowly patrol mangrove roots and rocks searching for green algae upon which they feed. They store some of the chloroplasts from eaten algae in their tissue, giving it the green coloration. The chloroplasts continue to function, providing the slug with photosynthetic energy. The ruffles along the back of the lettuce sea slug are called parapodia, and help provide more surface area for the chloroplasts to inhabit. They also camouflage the slug amongst the leafy algae that they live amongst. It is very easy to swim past a lettuce sea slug without ever noticing it.