31. Invertebrates

Which two animal groups are classified as ecdysozoans?

What is the process of ecdysis in arthropods?

What is the name of the tough outer covering constructed by ecdysozoans?

The arthropods superficially resemble earthworms in that both groups __________, yet the two are distinctly different because arthropods, but not earthworms, __________.

A major characteristic of arthropods is __________.

In most insects, gas exchange is accomplished by __________.

In arthropods, molting is necessary because __________.

Sowbugs are really crustaceans, not insects. Therefore, a sowbug does not have __________.

The majority of animal species are __________.

An unidentified species of animal displays the following characteristics: bilateral symmetry, a complete digestive system, an open circulatory system, distinct body segmentation, and a series of molting stages during growth. To which of the following animal phyla does this species most likely belong?

Complete metamorphosis __________.

Which of the following animals is most closely related to spiders?