Among the best known are the stingrays, which have a boneless body made of cartilage, with a fin on each side that extends from the head to the base of the tail.
Vienas no pazīstamākajām rajām ir dzeloņrajas (jeb dzelkņastes rajas), kurām, tāpat kā citiem rajveidīgajiem, ir skrimšļa skelets un abās pusēs ķermenim spura sniedzas no galvas līdz pat astei.