Arbo

Ekans is a purple, serpentine Pokémon. Its eyes, underbelly, the thick stripe around its neck, and the rattle are yellow. Ekans have three pairs of black lines encircling their body, and another line connects to each slit-pupil eye and curves toward its nose. Its large mouth has a round, pink tongue and no visible teeth. While painful, a newborn Ekans's bite is not venomous. This Pokémon grows longer with age.

Ekans live in grassy savannas and plains, moving stealthily through the grass. It can also be found in forests and desolate wastelands, where it preys on Eggs from and Spearow nests but will strike other prey from behind. By flicking its tongue out, it can detect danger and the scent of prey. Its jaw can detach to swallow large prey, but such a meal can make Ekans too heavy to move or become stuck and cause them to faint. It wraps itself around tree branches at night to rest. If not in a tree, it will coil itself up—a position in which it can defend itself from all directions. In Pokémon the Movie 2000: The Power of One (M02), it is revealed to possess some swimming abilities. As shown in Pokémon Sleep, Ekans are known to sleep with their bodies all coiled up. It is believed that Ekans do this to terrify foes, no matter which direction the foe is.

Evolution
Ekans evolves into .

(Source: Bulbapedia)