The animal that lives with no brain and no blood

A starfish has no brain. Nor blood, nor heart. Instead, it pumps filtered seawater through a network of internal canals: the ocean itself serves as its circulatory system.

Its «thinking» is spread out: a ring of nerves around the mouth and a network running down each arm decide, all together, which way to go. It sees with eyespots on the tips of its arms, which tell light from shadow.

And then there's its most famous trick: regeneration. If it loses an arm, another grows back. Some species go further: from a single severed arm with a piece of the central disc, a whole starfish can regenerate. For years, the fishermen who chopped them up to «get rid» of them from the oyster beds were, without knowing it, multiplying them.

Life doesn't need to look like us to work beautifully.

Source: National Ocean Service (NOAA)