Tossup
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 SSaDV caused a mysterious “wasting disease” in these organisms. The Triton Snail is one of the few natural predators capable of containing outbreaks of a corallivorous type of these animals in the genus Acanthaster. Studying the purple Pisaster genus of these animals in rocky intertidal ecosystems led Robert Paine to coin the term “keystone species.” For 10 points, what echinoderms are named for having five arms? ■END■
ANSWER: starfish [or sea stars; accept Asteroidea; accept specific species like purple sea star or common sea star or crown-of-thorns sea star; accept Acanthaster planci until read; prompt on Asterozoa; prompt on echinodermata; reject “brittle stars”]
<Carnegie Mellon A, Biology>
= Average correct buzz position
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