Invertebrates Chapter 33 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

Why do sponges (phyla Calcarea and Silicea) represent a separate lineage, distinct from all other animal phyla? They are sedentary and resemble plants. Most individuals are hermaphrodites. They do not have specialized cell types. They have only two layers of cells. They lack true tissue layers. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

Cnidaria include groups with a variety of body forms, but all share which common feature? All are filter feeders. All are strong swimmers. All have a gastrovascular cavity and tentacles. All live in tropical oceans. All reproduce mainly asexually. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

The group known as Lophotrochozoa includes about 18 animal phyla (all Bilateria except nematodes, arthropods, echinoderms, and chordates) and has a huge diversity of body forms. On what basis are all these animals thought to be in the same clade? DNA sequences embryo structure body cavity type of skeleton arrangement of appendages Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

Among flatworms that are internal parasites, which of the following would be expected? light-sensitive eyes prolific asexual reproduction in a vertebrate host limited to microscopic size suckers or piercing mouthparts defenses against host immune systems Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

The clam, snail, and octopus are all molluscs The clam, snail, and octopus are all molluscs. The muscular foot of a snail is homologous to, i.e., derived from the same structure as, which one of these? head of the octopus shell of the clam legs of the octopus siphon tube of the clam mantle of the clam Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

The evolutionary origin of extensive complexity in arthropod body plans is thought to be associated with which of these morphological changes? the origin of a chitinous exoskeleton the origin of numerous appendages the specialization of diverse body segments the addition of numerous identical body segments the fusion of body segments and reduction of appendages Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

Which of these genetic changes is thought to have led to the increasing complexity of the arthropod body plan? increased number of Hox genes for body segmentation changes in regulation of Hox genes for body segmentation increased number of Hox genes for appendages changes in regulation of Hox genes for appendages increased complexity in genes for exoskeleton arrangements Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

Flatworms, roundworms, and segmented worms share all of the following traits except which one? bilateral symmetry three embryonic tissue layers presence of a digestive cavity digestive tract with mouth and anus muscle tissue and a hydrostatic skeleton Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

All of the following were important contributions to the large adaptive diversity of insects except which one? diverse mouthparts for feeding on different substances multiple origins of wings in different insect groups expansion of flowering plant diversity invasion of many terrestrial habitats by insects diverse reproductive and social behaviors Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

In addition to their molecular DNA similarities, the phyla Echinodermata (including sea stars) and Chordata (including the vertebrates) share which derived trait? body symmetry of adult animals type of skeleton means of locomotion development pattern of larvae type of circulatory system Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.