Vortex Snake in Lunar Bay
Vortex Snakes are relatively harmless enemies which will only hurt you if you bump into them. They are long, brown, and composed of segments, like a train's cars. All can be killed with a dual charge attack. A large stinger grows from the rear of their bodies, most likely a defensive appendage or perhaps used to burrow into the ocean floor. Appearing prominently in the Lunar Bay and Dark Sea levels, they were perhaps originally a species directly from Planet Vortex and then imported to Earth.
When they die, they disappear in a puff of foam, with a hissing sound.
In The New Machine, a variant of this species will actively pursue Ecco through the room near the end of the level.