Ekans is a purple, serpentine Pokémon. Its eyes, underbelly, stripe, and rattle are yellow. Ekans has three pairs of black lines encircling its body, as well as another line that connects each slitted eye and curves toward its nose. Its large mouth has a round, pink tongue and no visible teeth.
Ekans moves stealthily through grass and preys on Eggs from Pidgey and Spearow nests, but can strike other prey from behind. It grows longer with age and 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. Its jaw can detach to swallow large prey, but such a meal can make Ekans too heavy to move. A newborn Ekans's bite is painful, but not venomous. It flicks its tongue out to detect danger and the scent of prey. It was also shown in the second movie to possess some swimming abilities. Ekans lives in grassy savannas and plains.