Saturday, April 28, 2012

Impossible Plant-Animal Hybrid

Wildly bizarre half-plant/half-animal creature - with a lovely name "Eastern Emerald Elysia"

This beautiful leaf-shaped sea slug Elysia chlorotica lives in shallow pools along Atlantic coast of North America, eats algae with gusto - one meal is enough for its lifetime! - and by using photosynthesis like any other plant, shatters the most basic definition between the "animal" and "plant" kingdoms.

It may not be "easy being green", but for this slug it turned out to be highly efficient!

This is the ONLY natural example of genes shared between the living kingdoms of "plants" and "animals"

Shaped like a leaf? Check. Totally colored green? Check, although the young slugs are still colored brown until they eat their first "green" meal... but right after that, they're ready to make pigment chlorophyll a all by themselves for the rest of their lives!

One thing about Elysia chlorotica, "a sea slug that has stolen enough genes to become the first animal shown to make chlorophyll like a plant". They don't just use chloroplasts from the algae they eat - this phenomenon, though rare, is known as kleptoplasty. What's more, they seem to have the particular genes that make them able to keep processing these chloroplasts in a consistent and sustainable way:

What sort of surprises can be found in a humble shallow pool? Turns out, quite an awful lot! Elysia chlorotica likes to inhabit "salt marshes, tidal marshes, pools and shallow creeks, at depths of 0 m to 0.5 m". All this should serve as a good encouragement to look closer into swamps and marshes (provided they are not haunted by any mad scientist apparitions, or the feral Hounds of the Baskervilles). There is positively astonishing microscopic biodiversity to be discovered all around your feet!

Talk about true "slacker" of the animal kingdom!

Consider Elysia chlorotica: when it comes to consuming chloroplasts, one slurping is enough! "It's the ultimate form of solar power: eat a plant ONCE, become photosynthetic for the rest of your life":

Watch the video here of its feeding off the algae (very appetizing!).

"When it munches on its favorite food - intertidal algae Vaucheria litorea - it holds the algal strand firmly in its mouth and, as though it were a straw, sucks out the contents.

Once a young slug has slurped its first chloroplast algae meal, the slug does not have to eat again for the rest of its life. All it has to do is sunbathe".

Elysia crispata also stores and converts chloroplasts inside its tissues - here is a rare close up view under the hood of this "green machine":

The more scientific description of this creature sounds impressive enough - "a marine opisthobranch gastropod mollusc" - but its "Elysium" moniker is more intriguing: could there be a connection with Elysium Fields as a mythological concept of afterlife in use in Ancient Greece, and maybe even Eleusinian Mysteries - famous "magical rites-of-passage", highly psychedelic experiences, or rather just herbal drug-induced "highs"... Certainly, the gene magic that this slug demonstrates is worthy of a name related to Eleusinian Mysteries!

It's all in a family: one colorful character after another!

Elysia chlorotica may be the only real fusion of a plant and an animal out there, but it also belongs to fittingly flamboyant family: it's a member of the clade Sacoglossa in the family Placobranchidae, the so-called "sap-sucking sea slugs", as they live by "sucking the sap" from their favorite algae. The members of this clade may superficially resemble nudibranch kind - but they are every bit as bizarre-looking as their more well-known "nudi" cousins!

Here is a sample of sacoglossan's astonishing diversity:

Elysia chlorotica is related to Elysia ornata, which is truly "ornate" just as the name implies:

Elysia crispata does not have a shell and, because of its fanciful appearance, is also called "The Lettuce Sea Slug":

The inside of this slug is quite impressive: it looks as an avant-garde painting and would not seem out of place inside any NYC modern art gallery:

Here it is, tinged blue and all the more beautiful for it... (left image). On the right is yet another related cutie - Cadinella ornatissima, classified somewhere between nudibranch and sacoglossa kinds:

Thuridilla lineolata from Bunaken Marine Park, Sulawesi (shown left):

More diversity: Cyerce shown left, and Olea hansineensis from Friday Harbor Laboratories, San Juan Island, Washington:

So... should humans also learn the trick and start "vegetating"?

By now, after hearing about very "stressful" life this creature lives - think about turning green, sunbathing, swimming in energy - you may wonder if one day humans might not develop technology that would turn us into extremely efficient photosynthesis machines?

According to Proceedings of the National Academy of Sciences:

"Chloroplasts only contain enough DNA to encode about 10% of the proteins needed to keep themselves running. The other necessary genes are found in the algae's nuclear DNA. So the question has always been, how do they continue to function in an animal cell missing all of these proteins? It seems that the algal gene in E. chlorotica's sex cells could be passed to the next generation. Other animals are able to harness sunlight after eating plants, but this is only because they acquire entire plant cells, which is very different to transforming an animal cell into a solar-powered plant-animal hybrid."

"It is unlikely humans could become photosynthetic in this way... Our digestive tract just chews all that stuff up - the chloroplasts and the DNA"

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