Matt George published his study on the behavior and feeding efficiency of sea urchins in JEMBE, showing spine position matters! You can click here for the temporary link or look up the full reference:
George, MN and E. Carrington, 2014. Do spines matter? Implications of streamlining behavior for drift capture in three sea urchins. J. Exp. Mar. Biol. Ecol. 461:102-106.