Everyone is familiar with the fact that plants have the power to turn the sunrays into the energy while animals need to munch on food instead. But did you know that there are certain marine animals running on solar energy before it was cool? Last time we already talked about the nudibranch Shaun the sheep, but there are also other interesting nudis worth mentioning.
One of them is spectacular Phyllodesmium longicirrum. It is the largest one from the nudibranch family, measuring often more than 12 cm. Their characteristic feature is bodies covered in “cerata", which are finger-like projections. These have evolved into large flattened "solar paddles" to maximize nudi‘s ability to cultivate the chloroplasts on its body. So how does their green lifestyle look like? It is based on their symbiotic relationship with single-celled algae called zooxanthellae. To be more specific, as the nudibranch feeds on the soft-corals it also harvests the algae which further continues to live inside of slug’s body, and you can observe it in form of brown spots.
You must be wondering, how effective this solar diet actually is? The answer is quite a lot because a highly productive longicirrum can gather as much as one-quarter of energy from the photosynthesis. This can actually mean several months without eating.
Apart from its solar-energy, nudi gets also another benefit from its healthy diet. As it lacks any defensive mechanisms, it stores the toxic chemical from soft corals inside their bodies which serves them as protection against predators.
On the other hand, the algae also gets some advantages from this symbiosis. As needs to have a host organism in order to survive, the body of nudibranch simply provides it just another home. According to several studies, algae stored on slug’s body starts reproducing rapidly. Similarly to the plants in greenhouses, it has shown to produce more nutrients that they actually need which suggests that it has ideal living conditions.
There is no surprise that this sea slug has gained some sort of celebrity status amongst the divers – everybody wants to see it but only a few of them are lucky enough. If you are a long-time fan or just became one, you can try your luck in Padangbai, Bali because it is one of few places where you are able to spot it.
Solar powered nudis remain mysterious because scientists still do not know how they keep the algae alive inside their bodies yet also how it is possible that they are not destroyed by their digestion or immunity system? Answer to there questions could bring us some important findings applicable in the fields of immunology and genetics.