4) Diploblast marine animals with radial symmetry, mouthsurrounded by tentacles covered with stinging cells (cnidocytes)with microscopic harpoons that paralyze prey belong to the phylum____________

5) This very old animal phylum groups filter-feeding organismswhose bodies are covered with pores. They exhibit cell level oforganization, and asymmetrical bodies:

6) The first group of triploblast animals with cephalization anda bilateral body symmetry belongs to the phylum __________________.

7) Animals in the phylum ____________________ were the first tohave a complete gut tube with two openings, mouth and anus. Thereare free-living and very abundant forms, and also parasitic formsthat cause diseases to man and other vertebrates.

8) All worms with segmented body belong to the phylum____________________.

9) Animals with soft slime body, with or without shell, areclassified within this vey diverse phylum:

10) Indicate the name of the phylum and class of insects,crustaceans, spiders, scorpions, centipedes, and millipedes. Howmany known species are classified in this phylum?

11) What characteristic of sea urchins is shared with chordatesmaking these marine animals the closest relatives tovertebrates?

12) What characteristic of the body of adult sea urchins isshared with cnidarians? 13) Describe the defining characteristicsof chordates.
14) Describe the defining characteristics of the sub-phylumVertebrata.
15) List the classes of vertebrates and their definingcharacteristics.

16) How many living species of vertebrates have beendescribed?