how many spines do sea urchins have?

Answer 1

It varies with species. Anywhere from a couple of hundred to several thousand. If you look at the dried test (shell) of a sea urchin, you see that it is covered with tiny rounded bumps, like tiny half beads. Each of these little smooth round bumps is the "ball" of a ball and socket joint between the test and a spine (the spines are not rigidly attached, then can be moved about). So, if you count the number of these little bumps on the test you can determine the number of spines that urchin had.

Answer 2

none. they are an invertabrae (meaning NO spine) just like slugs and worms. As for the pointy spines, never counted.