Meet Elysia chlorotica: A sea slug that looks like a leaf
You know a slug the moment you see it and you can’t not notice these slimy creatures that crawl so slowly. Many species of slugs survive on fungi and dead leaves, decaying plants, and some even by eating other slugs! But what if we told you there is a special type of slug family that makes its own food? And much like plants, they do not prey on other organisms for their food. Welcome to the world of Elysia chlorotica.
Elysia chlorotica is a slug that looks like a leaf! It is typically seen in shallow waters on the East coast of North America. Because of its habitat, it is also called the ‘sea slug.’ This bright green slug is also called ‘emerald green sea slug’ or ‘eastern emerald elysia’! Want to know more about this amazing creature? Read on!
Half animal, half plant
Yes, you read it right! E. chlorotica is often described as half animal and half plant. But why? This strange creature of the sea feeds on an algae called Vaucheria litorea. During digestion, the algae are only partially destroyed, leaving chloroplasts from the algae inside E. chlorotica. Chloroplasts are special cells found in all plants that give the leaves a bright green colour. These same cells give the slug its beautiful emerald green, almost leaf-like colour, making them part plants! The chloroplasts, however, are not only limited to imparting physical characteristics to E. chlorotica, but also provides it other special functions! The chloroplast cells are stored in the highly branched digestive tract of the slug giving its body the characteristic vein-like appearance all over.
E. chlorotica can synthesise its food!
Yes, E. chlorotica can synthesise its own food! But how? The answer is quite simple. It does this by a process called photosynthesis! The slug spreads like a leaf when the sun is out in the sky. Chloroplasts contain a special green pigment called chlorophyll, which captures sunlight to perform photosynthesis. Actually, the chlorophyll uses sunlight to convert carbon dioxide (a gas found in the atmosphere) into carbohydrates (an energy source). This way, E. chlorotica is self-powered! This is a classic example of kleptoplasty, which means chloroplast robbery! Yes, there is a term for that! E. chlorotica uses (or steals) the chloroplasts of the algae (V. litorea) to use it on its own accord! Fascinating, isn’t it?
The sea slug can store chlorophyll for life
Many sea creatures have chlorophyll that they have absorbed from their prey. The Spotted Salamander and the Pea Aphid are some of the examples. So, what is so special about E. chlorotica? The difference between E. chlorotica and other marine creatures is that the latter can use chlorophylls for a limited period. This means E. chlorotica can retain and use the pigment for the rest of its life! This is because it acquires chloroplasts during its developmental stage, while transitioning from a larva to its adult form. The pigments then remain active for the rest of its life.
Survival without the sun
Lastly, the sea slug can survive for up to several months without sunlight. Surprising, isn’t it? Well, scientists are debating over whether chlorophyll is essential to the survival of E. chlorotica at all. And what is the extent of their dependence on this pigment for survival? Survival or not, one thing is for sure, these sea slugs can really inspire many a techie with their self-powered bodies!