Meet the sea squirt, the strange ocean animal that eats its own brain

The sea squirt, also known as a tunicate, is a peculiar marine creature that undergoes a bizarre metamorphosis as it grows up. This transformation involves the absorption and digestion of its own brain. A typical sea squirt, early in life, resembles a small tadpole with a tail, a primitive spinal cord, and a basic brain. These creatures navigate the ocean using their brains and sense their environment.

However, once they find a suitable spot, such as a rock or reef, they cease swimming and begin a process of radical change. This is where their brain absorption occurs, often metaphorically referred to as the sea squirt "eating" its brain. In reality, they are merely reabsorbing the neural tissue, which was no longer necessary for their new stationary existence.

The sea squirt's brain reabsorption serves a practical purpose, as maintaining a brain incurs significant energy costs in the stationary state. By giving up mobility and complex brain functions, the sea squirt conserves energy, allowing it to focus on feeding and reproduction. Surprisingly, the sea squirt has provided valuable insights into human biology and evolution.

Researchers have found that tunicates share a close evolutionary relationship with humans, and their early larval form bears similarities to the human spinal cord. Furthermore, studies on sea squirts have contributed to the understanding of neurodegeneration, as the breakdown of brain tissue in these creatures has parallels with the aging process in human brains.