Questions: Animal Body Plans and the Major Animal Phyla
4 questions to test your understanding
Score: 0 / 4
Question 1 Multiple Choice
Which feature shows that sea stars are more closely related to humans than to jellyfish?
ASea stars and jellyfish both have radial symmetry
BSea stars and humans are both deuterostomes, with bilateral larvae and the same pattern of early development
CSea stars and humans both have backbones
DSea stars and humans both have exoskeletons
Echinoderms and chordates are deuterostomes: in the embryo, the first opening (blastopore) becomes the anus. Sea star larvae are bilaterally symmetric. The adult five-part symmetry is a later change that does not reflect a close link to radially symmetric cnidarians.
Question 2 True / False
Flatworms, roundworms and earthworms all belong to the same phylum.
TTrue
FFalse
Answer: False
Flatworms are in Platyhelminthes, roundworms in Nematoda and earthworms in Annelida. Their similar long, soft bodies do not show a close relationship; anatomy and DNA place them on different branches of the animal tree.
Question 3 Short Answer
Name the four features that all chordates have at some stage of life.
Think about your answer, then reveal below.
Model answer: A notochord, a dorsal hollow nerve cord, pharyngeal slits (or clefts), and a muscular tail that extends past the anus (post-anal tail).
In humans most of these appear only in the embryo. The notochord is replaced by the vertebral column, the pharyngeal clefts form parts of the ear and throat, and the tail is reduced to the coccyx.
Question 4 Multiple Choice
Which phylum contains the largest number of known animal species?
AChordata
BMollusca
CArthropoda
DCnidaria
Arthropods, which include insects, crustaceans and arachnids, make up the large majority of described animal species. Their jointed appendages and chitin exoskeleton have been adapted to almost every habitat.