Mediterranean red sea stars, Mediterranean Sea

© Hans Leijnse/Minden Picture

Stars in daylight. Mediterranean red sea stars

Sea stars—often called starfish—are some of the most fascinating creatures to live in our oceans. For starters, despite their name, they aren't fish—they belong to a group of marine invertebrates called echinoderms. Like all echinoderms, sea stars are characterized by the radial symmetry of their bodies, which usually have multiple arms extending from the central disc.

Did you know that sea stars can regenerate their arms? This means if they are attacked by a predator, they can get back into shape eventually (and quite literally). In fact, some species can also regenerate an entirely new sea star from just the arm, provided it still has a bit of the central disc attached to it.