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All sea urchins have spines to protect their defense a step further. They can deploy
against predators. Clustered around the base the biting jaws—the heads—of their nipping
of the spines are small structures called pedicellariae like ninja throwing blades.
pedicellariae (peh-dih-seh-LAIR-ee-ee) that When harassed, a collector urchin launches
look like miniature jaws atop movable stalks. dozens, even hundreds, of pedicellaria heads
Pedicellariae work to remove sand and tiny into the surrounding water. These minute
organisms that land on or try to attach to an snapping structures form a protective cloud
urchin. One type of pedicellaria will also nip at around the urchin. Not only will they sink their
predators trying to push through the urchin’s razor-sharp fangs into any attacker they make
spiny defense. contact with, but they’ll also inject a painful
But collector urchins (Tripneustes gratilla) take dose of poison.
CLosE-UP Of A COLLECTOR URCHIN’S
“THROwING sTAR” PEdICELLARIA
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