Chapter Questions
Collar cells (choanocytes) are characteristic of (a) poriferans (b) cnidarians (c) most coelomates (d) lophotrochozoans (e) ecdysozoans
Cnidocytes (a) are characteristic of sponges (b) are found among cells lining the gastrovascular cavity (c) contain stinging organelles (d) are lined with mesoderm (e) have two main shapes
Which of the following is associated with the evolution of the coelom? (a) radial symmetry (b) tube-within-a-tube body plan (c) incomplete metamorphosis (d) bilateral symmetry(e) development of ganglia
Trochophore larvae are characteristic of (a) arthropods (b) cnidarians (c) flatworms (d) mollusks (e) crustaceans
Which of the following is not an adaptation to parasitic life? (a) production of a few well-protected eggs (b) hooks (c) suckers (d) reduced digestive system (e) intermediate host
An open circulatory system (a) is characteristic of squids and other active mollusks (b) permits contracting muscles to recover quickly (c) has no blood vessels (d) is a unique characteristic of annelids (e) has hemolymph, which bathes tissues directly
Which of the following characteristics is associated with mollusks? (a) mandibles (b) mantle (c) pedipalps (d) chelipeds (e) setae
Trilobites (a) were early mollusks (b) are onychophorans (c) are characterized by parapodia and setae (d) were early arthropods (e) are an evolutionary link between annelids and arthropods
Which of the following is not characteristic of arthropods? (a) exoskeleton (b) pseudocoelom (c) paired, jointed appendages (d) chitin (e) segmentation
Which of the following is characteristic of insects? (a) biramous appendages (b) two pairs of antennae (c) chelicerae (d) eight legs (e) mandibles
The correct sequence of complete metamorphosis of an insect is (a) egg $\rightarrow$ immature form $\rightarrow$ adult(b) $e g g \rightarrow$ trochophore larva $\rightarrow$ adult (c) egg $\rightarrow$ pupa $\rightarrow$ larva $\rightarrow$ adult (d) egg $\rightarrow$ larva $\rightarrow$ pupa $\rightarrow$ adult (e) adult $\rightarrow$ larva $\rightarrow$ egg $\rightarrow$ pupa
Draw a cross section through a hydra. Label the epidermis, gastrodermis, gastrovascular cavity, and mesoglea.
Discuss important adaptations made possible by the development of the coelom.
Discuss the idea that every evolutionary adaptation has both advantages and disadvantages, using each of the following as an example: (a) cephalization, (b) the arthropod exoskeleton, and (c) segmentation with specialization.
Imagine that you discover a new animal in a rain forest. It has an elongated, segmented body with bristles, and it has no obvious head. Where would you place this animal in the accompanying cladogram? Support your decision. Look at the more detailed cladogram in Figure 30-6a (in Chapter 30). What additional characteristicswould help you place your animal in this cladogram? Explain your decision-making process.
Why have biologists stopped using type of body cavity as a major criterion for inferring relationships among animal groups?
Animal body plans have generally evolved from simple to more complex. How can we explain the exceptions?
Insects that undergo complete metamorphosis outnumber those that do not by more than 10 to 1. Hypothesize an explanation.
Several international monitoring projects are gathering data to help us understand coral reef destruction. In your opinion, why is it important to take action to protect coral reefs? What role might technology play?