It is not a tiger tail, but it doesn't have filter tentacles, so it is definately a detrivore. This means it is a good cucumber for your tank. Unfortunately your gravel in the pic looks too big for it. It can possible starve if you keep it in that tank.
edit- Yes, upon second viewing of your gravel, that cuke is going to starve in there.
hey pelena i agree with mud. you need more sand. i got the same guy in my tank. sand goes in,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,sand comes out. he gets the algae off of my glass too.(but only at night.........i caught him with my flashlight)