Chapter Questions
Which of the following is not part of the molluscan body plan?a. Mantleb. Footc. Radulad. Visceral masse. Jointed appendages
The outer covering of ecdysozoansa. is always hard and rigid.b. is always thin and flexible.c. is hard and rigid in larvae but thin in adults.d. ranges from very thin to hard and rigid, depending on the species.e. grows throughout life to accommodate a growing body.
Which groups are arthropod relatives with unjointed legs?a. Trilobites and onychophoransb. Onychophorans and tardigradesc. Trilobites and tardigradesd. Onychophorans and cheliceratese. tardigrades and chelicerates
The body plan of insects comprises which of the following three regions?a. Head, abdomen, and tracheab. Head, abdomen, and cephalothoraxc. Cephalothorax, abdomen, and trachead. Head, thorax, and abdomene. Abdomen, trachea, and mantle
Insects whose hatchlings are sufficiently similar in form to adults to be recognizable are said to havea. instars.b. neopterous development.c. accelerated development.d. incomplete metamorphosis.e. complete metamorphosis.
Factors that may have contributed to the remarkable evolutionary success of insects includea. the lack of any other similar organisms in the terrestrial environments colonized by insects.b. the ability to fly.c. complete metamorphosis.d. a new mechanism for delivering oxygen to their internal tissues.e. All of the above
Segmentation either has arisen several times during animal evolution, or else arose early in animal evolution and was subsequently lost multiple times. What advantages does segmentation provide? Given these advantages, why might some animals have lost their segmentation?
Major structural novelties have arisen only infrequently during the course of evolution. Which of the features of protostomes do you think are major evolutionary novelties? Which of these features may have led to major evolutionary radiations?
There are more described and named species of insects than of all other species on Earth combined. However, only a very few insect species live in marine environments, and those species are restricted to the intertidal zone or the ocean surface. What factors may have contributed to the insects' lack of success in the oceans?
In the Working with Data exercise on page $673,$ you were asked to make many assumptions to estimate the number of species of insects on Earth. Do you think these assumptions are reasonable? Why or why not? Would you argue for a different set of assumptions? How do you think these changes in assumptions would affect your calculations? Can you think of ways to test these assumptions?