Starfish are honestly one of the wildest animals in the ocean, and I feel like people don’t give them enough credit. When you first look at them, they just seem cute and simple, almost like ocean décor, but once you learn how they actually function, it’s kind of shocking. These animals have no brain, no blood, and they still manage to move, hunt, survive, and even regrow their arms if they lose one. Nature really snapped with them.

Image from Unsplash

Most animals depend on a brain and blood to live, but starfish use something completely different. Instead of blood, their whole body runs on seawater. They pull water in and pump it through a system called the water vascular system, and that’s what powers their tube feet. Those tiny feet on the bottom of their arms are how they walk, hold onto rocks, and even open clams. Their entire life depends on ocean water the same way ours depends on blood.

Image from NOAA National Marine Sanctuaries

Now, the no brain part is what shocks everyone the most. Starfish don’t have a brain at all, just a nerve ring in the center and nerve networks inside each arm. Each arm can basically think for itself, but all of them still work together. Even without a brain, starfish can sense light, find food, avoid danger, and move with coordination. It’s like their whole body is running off teamwork.

And the regeneration part, that’s honestly their superstar ability. If a starfish loses an arm, they can grow it back. This isn’t a quick process, but it’s still crazy that they can do it at all. Some species can even regrow an entirely new starfish from just one surviving arm, as long as part of the center is attached. So losing an arm doesn’t stop them, they just rebuild it.

Image from Techno-Science.net, based on Current Biology research

Starfish might look simple on the outside, but their biology is honestly on another level. They remind you that nature doesn’t always follow the rules we expect. Even without the things we consider “necessary” to stay alive, starfish still thrive, survive tough environments, and rebuild themselves when they need to. It’s kind of inspiring when you think about it.