With over 2,000 species, starfish (also known as sea stars) are some of the most striking creatures in the ocean.

They come in various colors, shapes, and sizes, and boast an incredibly unique anatomy.

Despite lacking a brain or blood, these remarkable marine animals have the ability to digest food outside their body.

1. Starfish Can Regenerate Their Arms

One of the most fascinating features of starfish is their ability to regenerate lost arms. Whether they lose an arm due to a predator attack or to escape danger, starfish can grow it back over time. This process can take months, or even years, depending on the species. If the severed arm is undamaged, it has the potential to regenerate into an entirely new, genetically identical starfish—an incredible survival mechanism.

2. No Brain or Blood

Despite the absence of a brain or blood, starfish thrive in the ocean's depths. Instead of blood, they circulate seawater through their bodies, which helps deliver essential nutrients to their organs and keeps them functioning. This system is more efficient in saving space, eliminating the need for a complex circulatory system. The abundance of seawater around them ensures they never run out of this vital resource.

3. Tough, Leathery Skin

Starfish are protected by a durable outer layer made from calcium carbonate. This tough skin helps them resist predators. Some species even have spines protruding from their skin, adding an extra layer of defense to deter potential hunters.

4. Starfish Have Eyes

Though starfish lack a brain, blood, and a central nervous system, they do have eyes at the tips of their arms. While their vision isn’t as advanced as ours, these eyes can detect light variations, which help starfish navigate their environment. This capability allows them to hunt for food and avoid predators effectively.

5. Starfish Move with Hundreds of Feet

Starfish are equipped with hundreds of tiny tube feet located on the underside of their arms. These feet fill with seawater, creating a hydraulic movement that allows the starfish to crawl along surfaces. This mechanism enables them to move surprisingly fast, especially considering their appearance.

6. Starfish Can Eat Outside Their Body

Starfish have a small mouth on the underside of their body, but they’ve developed a unique feeding strategy. They can extend their stomach outside their body to digest food before bringing it back inside. This method allows them to consume prey larger than what could fit through their mouth, making digestion more efficient.

7. Not All Starfish Are Star-Shaped

While most starfish have the iconic star shape, some species deviate from this design. For example, the Cushion Starfish has a round, blob-like form but still possesses the essential traits of a starfish. This species is more gentle than others, feeding on detritus and plants, while most starfish prey on clams and oysters.

Starfish may have an unusual anatomy, but their unique features are vital for their survival in the ocean!