The creature that eats its own brain: A curious tale of Sea Squirt

The ocean contains many organisms whose form defies the expectations we might have for life, but none may be more bizarre than the sea squirt. While at first glance it looks like nothing more than another rock-attached blob, its early development could not be more unlike any blob's. It possesses the abilities of mobility and choice and even has something akin to a brain. But perhaps most remarkable of all is what the sea squirt does with this brain; it eats it. This strange transformation, where it digests its own brain after settling in one place, has fascinated scientists studying evolution and the origins of intelligence.

What is a Sea Squirt, and how does it live

Sea squirts, or ascidians, are marine invertebrates normally found clinging to rocks, the hulls of ships, and coral reefs. As adults, sea squirts have a sac-like body which resembles a tube and strain the water for food. Nevertheless, sea squirt larvae look totally different.

The larvae are swimming freely and are similar to tadpoles, having a notochord, which is similar to a primitive backbone, a tail, and even a simple brain structure used for orientation.

As per the study "Sea Squirt Ciona intestinalis," sea squirt larvae are able to seek out an appropriate surface on which to stick. After finding a proper place, the most amazing things happen.

Why the Sea Squirt eats its own brain

Once attached to an object, the sea squirt embarks on an incredible change. It devours its tail, and in what can be considered the most unbelievable part of this metamorphosis, digests its brain. While it may seem like a very extreme thing, the sea squirt does it out of necessity.

As pointed out by scientists, once the sea squirt attaches itself, it loses the need to move or think. According to research ‘The larval ascidian nervous system: the chordate brain from its small beginnings:’

“The larval nervous system is quickly degraded during metamorphosis,” ensuring the organism expends less energy. The maintenance of the brain uses up a lot of energy, which is then best spent elsewhere. In other words, the sea squirt sacrifices its brain for its survival benefits.

What this teaches us about evolution and intelligence

The life cycle of a sea squirt demonstrates an interesting perspective into evolution and how it shapes living things according to what they need. Evolution does not necessarily progress to increasing complexity in some cases.

Sea squirts belong to the same class as vertebrates, making this life cycle particularly interesting. Even though sea squirts have no brains, their initial characteristics place them within more complex species, such as humans.

This odd life form goes against the belief that having a high intelligence level is an advantage for survival. This is because the intelligence of sea squirts is only helpful for a short time. After which, the organism has adapted itself to function without it.

To conclude, the case of the sea squirt shows that surviving in nature does not have anything to do with intelligence or complexity. Rather, it involves efficiency. It is not a handicap for the organism to digest its brain because this process is a carefully planned evolutionary adaptation.