Starstars or starstars are star-shaped echinoderms belonging to the Asteroid class. Common use often finds these names that also apply to ophiuroids, which are correctly known as fragile stars or basket stars. Around 1,500 type of starfish are found at the bottom of the sea in every the world’s oceans, from the tropics to the cold polar waters. They are found from the intertidal zone to abyssal depths, 6,000 m (20,000 ft) below the surface.
Starfish are marine invertebrates. They usually have a central disc and five arms, although some type have a larger number of arms. The boral or top of the surface can be smooth, granular or prickly, and is covered with overlapping plates. Many type are brightly colored in several shades of red or orange, while others are blue, grey or brown. Starfish have tube legs operated by a hydraulic system and a mouth in the center of the oral or lower surface. They are opportunistic feeders and are mainly predators in benthic invertebrates. Several type have specialized feeding behaviors, including the eversion of their stomachs and the feeding by suspension. They have complex life cycles and can reproduce both sexually and assexually. Most can regenerate damaged parts or lost weapons and can throw weapons as a means of defense. The Asteroid occupies several significant ecological roles. Starfish, such as the ocre starfish (Pisaster ochraceus) and the Recife starfish (Stichaster australis), became widely known as examples of the Keystone type concept in ecology. The tropical starfish (Acanthaster Planci) is a voracious coral predator throughout the Indo-Pacific region, and the North Pacific Ocean is considered one of the 100 most invasive type in the world.
The fossil record of starfish is ancient, dating back to the Ordovician about 450 million years ago, nevertheless it is quite scarce, as starfish tend to disintegrate after death. Only the animal’s ossicles and spines are likely to be preserved, so it is still difficult to find. With its attractive symmetrical shape, Starfish has played a role in literature, legend, design and popular culture. Sometimes they are collected as curiosities, used in design or as logos, and in some cultures, despite the possible toxicity, are consumed.