The starfish belongs to the phylum of echinoderms; they are cousins of sea urchins and inhabit all the oceans around the world. Most starfish have five limbs. But this is not the case for all: some species can have up to 50 well-developed arms and others have limbs so short as to seem pads. Starfish spend the day in search of food, and their favourite prey are sea urchins and mussels.
Starfish have the ability to open the shells of mussels due to the strength of their arms, and they evert their stomachs from their mouths so as to digest molluscs externally. Starfish have a significant regenerative capacity: if they lose a limb, in fact, they are able to grow another one just like it.