Question

The higher invertebrates are divided into two evolutionary lines, protostomes and deuterostomes. This division is based on which developmental feature?
A.wether the blastopore ultimately develops into a mouth or an anus

B. wether the embryonic cells undergo spiral or radial cleavage

C. wether the coelom forms by splitting the mesoderm or through the pocket of the gut.

Answer 1

The answer is A whether the blastopore ultimately develops into a mouth or anus

i know because i just took a test and passed with this same question

Answer 2

Answer:

A. whether the blastopore ultimately develops into a mouth or an anus

Explanation:

The higher invertebrates are divided into two evolutionary lines named protostomes and deuterostomes based on whether the blastopore ultimately develops into a mouth or an anus. Blastopore is the first developement opening of archenteron (rudimentary alimentary canal) which appears during gastrula stage. If during embryonic development, the blastopore develops into mouth then the animal is known as protostome whereas development of anus from blastopore will make the invertebrate a deuterostome.

Invertebrates like annelids, arthropods and molluscs are examples of protostomes while echinoderms are examples of deuterostomes.