Dr. J’s Slam Dunk: Show off your knowledge from the exam ch…
Questions
Dr. J’s Slаm Dunk: Shоw оff yоur knowledge from the exаm chаpters that was not already included on the exam (Wow Kimzey, 2014). ≤2pts
Mоllusks (Phylа Mоlluscа) Mоllusks аre extremely diverse-and important to humans. Mollusks range from microscopic to huge and exhibit many different forms. They all have a coelom surrounding the heart. The mollusk body plan is complex and varied. Mollusks are generally bilaterally symmetrical, at least at some point in their lives. They use a muscular foot (podium) for locomotion, attachment, food capture, or a combination. The mantle is a thick epidermal sheet that forms the mantle cavity. It houses the respiratory structures (ctenidia or gills), and digestive, excretory, and reproductive products are discharged into it. The outer mantle secretes a protective calcium carbonate shell. Some mollusks have internal or reduced shells, or none at all. All mollusks except bivalves have a radula, a rasplike structure used in feeding. Most have an open circulatory system, but cephalopods have a closed circulatory system. In many mollusks, an embryo develops into a free-swimming trochophore larva. In some bivalves and gastropods, the embryo becomes a free-swimming veliger larva. Four classes of mollusks show the diversity of the phylum. The four best-known classes are Polyplacophora (chitons), Gastropoda (snails and slugs), Bivalvia (clams, mussels, and cockles), and Cephalopoda (octopuses, squids, and nautiluses). Figure 4Figure 4. Photos show the diversity of mollusks. (a) the flame scallop. (b) the common octopus. (c) nautiluses. (d) the banana slug.
Bryоzоаns (Phylа Bryоzoа) and Brachiopods (Phyla Brachiopoda)Bryozoa and Brachiopoda are characterized by a lophophore, a U-shaped ridge around the mouth bearing ciliated tentacles. Bryozoans are the only exclusively colonial animals. Each individual zooid produces a chitinous chamber called a zoecium that attaches to substrates and other colony members. Brachiopods and phoronids are solitary lophophorates. The body of brachiopods is enclosed between two calcified shells that are dorsal and ventral, not lateral as in bivalves. Roundworms (Phyla Nematoda)Like other members of the superphylum Ecdysozoa, the Nematoda are triploblastic and possess an embryonic mesoderm sandwiched between the ectoderm and endoderm. They are also bilaterally symmetrical, meaning a longitudinal section will divide them into the right and left superficially symmetrical sides. In contrast with flatworms, nematodes are pseudocoelomates and show a tubular morphology and circular cross-section. Nematodes include both free-living and parasitic forms. Nematodes reproduce sexually and exhibit sexual dimorphism. More species of nematodes may exist than species of arthropods. Nematodes, including hookworm, pinworm, trichinosis, intestinal roundworm, and filariasis, cause some important human, veterinary, and plant diseases.