Translation of "Spines" in Spanish

Do you know why cacti have spines?

¿Sabés por qué los cactus tienen espinas?

A thistle is like a prickly person, lots of spines.

El abrojo es como un cardo, con muchas espinas.

What she noticed was people's spines with a flatter lumbar curvature

Ella notó que la columna de las personas con una leve curvatura lumbar,

Than getting into that big old barrel cactus that's covered in these spines and also these little hairs.

que a aquel cactus de barril cubierto de espinas y vellos.