Which of the following is a deuterostome, but not a vertebrate?

Question

A lancelet, a lamprey, a frog, a bird, or a millipede

 

Answer 1

Hi Adrianna.

Your question is a good one! A Deuterostome, versus a Protostome. The Protostome shows spiral cleavage at the eight-cell embryonic stage and forms its mouth directly from the blastopore. The Deuterostome shows radial cleavage at the eight-cell embryonic stage and forms its anus directly from the blastopore.

Which of the following is a deuterostome, but not a vertebrate?

1. lancelet
2. lamprey
3. frog
4. bird
5. millipede

There are 3 vertebrates on this list: Lamprey, frog, bird. There are 4 Deuterostomes on this list: lancelet, lamprey, frog, bird.

The millipede is an invertebrate, but it is a Protostome.

That leaves us the lancelet as the only Deuterostome on the list that is not a vertebrate.