[Campbell Biology P.734] The main distinction between sponges Porifera and most other animal... | Practice Question

The main distinction between sponges Porifera and most other animal phyla is based on the absence versus the presence of which characteristic?

  • A: a body cavity
  • B: a complete digestive tract
  • C: mesoderm
  • D: tissues

Explanation

The phylogenetic tree in Figure 32.11 shows 'Tissues' as a key evolutionary step after Porifera, distinguishing Eumetazoa animals with true tissues from basal animals like sponges. Sponges are the only extant animal phylum that lack true tissues.