The animal phylum most like the protists that gave rise to the animal kingdom is _____.
( Evidence that supports this includes the lack of true tissue in sponges and the close similarity between choanocytes and choanoflagellates.)
Which of the following is not a characteristic of cnidarians?
( Cnidarians are diploblastic, lacking mesoderm.)
All of the following are true of the phylum Platyhelminthes except _____.
they are all parasitic
( Planarians are an example of a free-living flatworm. Turbellarians are not usually parasitic.)
Some species of rotifers consist solely of females. Their method of reproduction is described as _____.
( The females lay unfertilized eggs that develop into females.)
Bryozoans, phoronids, and brachiopods are collectively referred to as _____.
( The lophophore is a structure common to these three phyla that bear ciliated tentacles.)
The phylum Nemertea, the proboscis worms, differs from the phylum Platyhelminthes in that proboscis worms _____.
have a complete digestive tract
( Flatworms—with the exception of tapeworms, which lack a digestive tract—have a gastrovascular cavity.)
Members of the phylum Mollusca _____.
are soft-bodied and usually covered by a shell
( Members of the phylum Mollusca are soft-bodied and are usually covered by a shell.)
A marine biologist dredges up a small animal from the bottom of the ocean. It is uniformly segmented, with short, stiff appendages and soft, flexible skin. It has a complete digestive system and an open circulatory system, but no skeleton. Based on this, you determine that the animal must be a(n) _____.
(The description matches the characteristics of annelids.)
What structure is responsible for gas exchange in most spiders?
( The extensive surface area of book lungs is a structural adaptation that enhances the exchange of O2 and CO2 between the hemolymph and air.)
Which of the following are thought to be most closely related to humans?
( Both humans and sea stars are deuterostomes.)