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 (10[1])studies have disproved the theory that the densovirus SSaDV caused a mysterious “wasting disease” in these organisms. The (-5[1])Triton Snail is one of the few natural predators capable of containing outbreaks of (10[1])a (10[1])corallivorous type of these animals in the genus (10[1])Acanthaster. Studying the (10[1])purple Pisaster genus of these animals in rocky intertidal ecosystems (10[2])led Robert Paine to coin the term “keystone species.” For 10 points, what echinoderms are named (-5[1])for having five arms? ■END■ (10[2])