mollusks
Which of the following statements about the anatomy of a mollusk is false? a. Mollusks have a radula for scraping food. Mollusks have ventral nerve cords. The tissue beneath the shell is called the mantle. The mantle cavity contains hemolymph. Mollusk Diversity This phylum is comprised of seven classes: Aplacophora, Monoplacophora, Polyplacophora, Bivalvia, Gastropoda, Cephalopoda, and Scaphopoda. Class Aplacophora bearing no plates includes worm-like animals living mostly on deep ocean bottoms. These animals lack a shell but have aragonite spicules on their skin. Members of class Monoplacophora bearing one plate have a single, cap-like shell enclosing the body. The monoplacophorans were believed extinct and only known as fossils until the discovery of Neopilina galatheae in 1952. Today, scientists have identified nearly two dozen living species. Animals in the class Polyplacophora bearing many plates are commonly known as chitons and bear an armor-like, eight-plated shell Figure 15.25 . These animals have a broad, ventral foot that is adapted for attachment to rocks and a mantle that extends beyond the shell in the form of a girdle. They breathe with ctenidia gills present ventrally. These animals have a radula modified for scraping. A single pair of nephridia for excretion is present.