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@Yasi
Characteristics of sea stars (or starfish)
Sea stars are characterized by radial symmetry, several arms (5 or multiplied by 5) radiating from a central body. Mouth and anus are close together on the underside, the anus is at the center of the disc together with the water intake (madreporite). The upper surface is often very colorful. Minute pincer-like structures called pedicellaria are present. These structures ensure that the surface of the arms stay free from algae. The underside is often a lighter color.
There are a few starfish that have 6 or 7 arms, for example Echinaster luzonicus or Protoreaster, some even more like the elven-armed sea star (Coscinasterias calamaria). Others normally have 5 arms but now have more arms, because after an injury an arm divided and grew into two arms.
They have a mouth anus :O