A species of these organisms that act as pests in one ecosystem are injected with bile salts using autonomous drones like RangerBot. A relaxin-like peptide hormone found in these organisms called “gonad-stimulating substance” makes them a useful model to study oocyte maturation. They aren’t deer, but two recent studies have disproved the theory that the densovirus (-5[1])SSaDV caused a mysterious “wasting disease” in these (10[1])organisms. (-5[2])The (-5[1])Triton Snail is one of the few (-5[1])natural predators capable of containing outbreaks (-5[1])of a corallivorous type of these animals in the genus (10[2])Acanthaster. (-5[1])Studying the (10[1])purple (10[1])Pisaster (10[4])genus (10[1]-5[1])of these animals (10[1])in rocky intertidal ecosystems (10[1]-5[1])led Robert (10[1])Paine (-5[1])to coin the term “keystone species.” (10[2])For 10 points, what echinoderms are named (-5[1])for having five arms? (10[1])■END■ (10[13])