Hitodeman

Staryu is a golden-brown, echinoderm Pokémon with faceted skin and five appendages. These appendages surround an exterior organ called the core. The core resembles a golden metal casing with a red gem in the center, which is held in place by a golden ring looped around Staryu's lower left point. Staryu have no jointed limbs to speak of, instead using their psychic powers to move themselves around. If any of Staryu's appendages are lost or eaten by predators like Lumineon, it is unharmed and can grow them back with ease provided the core is still intact.

When the sun goes down, Staryu's core glows its brightest. Many Staryu will float from the seafloor to the surface and align themselves with stars of the night sky as their core flickers, displaying a connection with the celestial bodies of space. In the Pokémon the Series: The Beginning episode Bye Bye Psyduck (EP093), it is shown that if Staryu becomes weak, its core will grow faint and flash slowly. During the ends of summer, groups of Staryu tend to gather while lighting up in a steady rhythm. Staryu can be found at the very bottom of the ocean on the seafloors. There are times, however, when Staryu finds itself in rivers that lead into the ocean as seen in Pokémon Snap.

In the Pocket Monsters Encyclopedia, and the original Japanese version of the Pokémon the Series: The Beginning episode The Water Flowers of Cerulean City (EP007), Staryu is classified as hermaphroditic.

Evolution
Staryu evolves into .

(Source: Bulbapedia)