There’s a strange little creature in the ocean that does something remarkable as it grows up: it absorbs and digests its own brain. Known as the sea squirt, or tunicate, this unusual marine animal offers a fascinating glimpse into evolution, challenging how we think about intelligence and even our own origins.Sea squirts start life a lot like tiny tadpoles. In their early days, they swim freely through the ocean, equipped with a tail, a primitive spinal cord, and a basic brain. They use this brain to navigate, sense their surroundings, and find a safe place to settle. But here’s where things get weird.DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to.Once the young sea squirt finds a rock or reef to attach itself to, it stops swimming and basically gives up the need for a brain. It undergoes a complete transformation, called metamorphosis, during which it absorbs many of the body parts it no longer needs, including its tail, its spinal cord, and yes, even its brain.This process has often been described as the sea squirt “eating” its own brain. While that’s a dramatic way to put it, it’s not entirely wrong. The creature reabsorbs the neural tissue it once used to think and move, and recycles it to fuel its new, stationary life. In other words, it digests the parts it no longer needs so it can survive in a new way. In their early days, they swim freely through the ocean, equipped with a tail, a primitive spinal cord, and a basic brain. (Source: Wikimedia Commons)It sounds extreme, but for the sea squirt, it actually makes a lot of sense. Once it’s anchored in place, it doesn’t need to move or sense the world the way it used to. Maintaining a brain is expensive in terms of energy, so the sea squirt makes a trade-off: give up its mobility and complexity in exchange for a simple life as a filter feeder.Its body grows a sac-like structure and starts pulling nutrients from the water. The energy it saves by letting go of its nervous system helps it focus entirely on eating and reproducing.Story continues below this adTurns out this odd little animal has taught us much. Researchers have discovered that tunicates are closely related to humans in the evolutionary tree. In fact, their early larval form includes a structure similar to a human spinal cord, making them a key link in understanding how vertebrates evolved.Scientists at Stanford and other institutions have even studied sea squirts to better understand neurodegeneration, since the way they break down their own brain tissue shares similarities with how human brains age and change over time.Explore more captivating stories about pets and animals here, and make us your daily stop for the latest from the animal kingdom.DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to.