Black plastic hoses?

I know this may be a dumb question but what are those black plastic like hoses under hood called? They have little ridges going the entire length and some of them have clamps on them. not the radiator hose or anything like that. I'm asking because one of mine has a long split down the middle of it. I noticed it while I was changing my air filter. Is that a problem? I need to know the name of it. Thanks.
Black plastic hoses?
It's actuallly a wire wrap. that's how they are made, it keeps several wires together and it also keeps them free of dirt and out of the way of moving parts
Black plastic hoses?
I don't know, but is it just one of the hoses that is holding wires together? I know those have long splits down them sometimes. Otherwise I am just not sure what plastic like hose it could be.

lol, that's what I was talking about Duce, I just didn't know what it was actually called. Glad someone else thinks that too, my answer wasn't way off then.
There two types of hose that look like that. One is what Duce described, and is called convolute. It protects wiring from abrasion mainly. It has a split in the middle so that the wiring can be inserted, or removed for that matter. The other type that looks similar is the tubing used for evaporative emissions. Instead of short squared off ridges like convolute, this type tubing has rounded ridges, and has nothing inside it. A simple inspection and a squeeze will tell what type hose it is. If it's convolute, it's supposed to be split. If it's not, your check engine light will be on soon!