Which combination of features would occur in a typical animal?
multicellular, heterotrophic, obtain food by ingestion, lack cell walls
All animals can probably trace their lineage to a common ancestor that lived in the _____.
mid to late Precambrian (1 billion years ago or less)
If an organism is a protostome, what else can you conclude about its body plan?
It is bilaterally symmetrical and has three tissue layers.
which phyla both possess a gastrovascular cavity that has only one opening?
Cnidaria and Platyhelminthes
In the ocean, you find an organism with a hard exoskeleton and jointed legs. It is _____.
an arthropod, and probably a crustacean
Which feature of insects has promoted their diversification and evolutionary success?
Insects have repeated modular segments that develop independently of each other. Thus, insects have been able to evolve appendages that are specialized for diverse functions.
Which of the following is evidence that the extant phylum most closely related to chordates is Echinodermata?
They are both deuterostomes.
Which characteristic is unique to Chordata (it is a diagnostic feature) and is evident at some stage of the life cycle in all chordates?