One extinct member of this phylum was the most common animal of the Cambrian Explosion.
Along with mollusks, this grouping is defined by the existence of a cavity for blood circulation known as the hemocoel (HEE-moh-"SEAL"). This phylum takes in oxygen through stacks of plates filled with blood known as book lungs. One extinct member of this phylum was the most common animal of the Cambrian Explosion. That animal was a three lobed marine creature known as the trilobite (TRY-lo-bite). Members of this phylum have exoskeletons made of chitin (KYE-tin). For 10 points, name this phylum that includes crustaceans (crus-TAY-"shins") and insects.
Along with mollusks, this grouping is defined by the existence of a cavity for blood circulation known as the hemocoel (HEE-moh-"SEAL").
{Arthropoda} [or {arthropods}]