The favorite prey of starfish are the same as they themselves inactive animals – sea urchins and bivalve mollusks. Bivalve mollusks have shells, the valves of which are tightly closed in case of danger, so the starfish call them differently. First, the starfish is glued with two rays to the sink shells, and then starts to push them apart. It must be said that the ambulacral legs are firmly adhered to the substrate due to the adhesive lubrication and one single ambulacral stem can develop a force of up to 30 g! And on each ray of the starfish there are hundreds of them, so she, like a real strongman, pushes the shells with an effort of several kilograms. However, it is not necessary to push the sash openings all the way to the starfish, for a satisfying lunch it has enough slots of 0.1 mm! In this truly microscopic gap, the star of the sea turns its stomach (it can stretch for 10 cm) and digests the mollusk in its own house.
Another strong, in the literal and figurative sense of the word, the system of starfish is the digestive system. The mouth of these animals is located in the center of the disc on the underside of the body, and the tiny anal opening is on the back. By the way, they rarely use starfishes (in some species it generally overgrows), preferring to remove undigested food leftovers through the mouth. The stomach of these invertebrates has outgrowths that extend into the rays, they store nutrients in case of hunger. A starving starfish regularly, because during breeding they stop eating. The stomach in many species can turn outward through the mouth opening, and it stretches like rubber, taking any shape. Due to the extensible stomach, the starfish can digest prey exceeding its size. A case is known when the starfish of Luidia swallowed so large a sea urchin that it died, unable to spit out its remains.