Deuterostomes vs Protostomes

Question 1

What taxonomic rank are Deuterostomes and Protostomes, what is the rank immediately preceding them, and when did they diverge?

Answer 1

Subphylum, Bilateria, ~600 mya

Question 2

What are the main Deuterostome phyla?

Answer 2

Chordates, hemichordates, echinoderms

Question 3

In deuterostome development, the blastopore (first opening) becomes the ____ on the _____ end

Answer 3

anus, posterior

Question 4

Where is the nerve cord on deuterostomes?

Answer 4

Dorsal

Question 5

What happens if the blastomere separates in a deuterostome and what is that called?

Answer 5

Each becomes an individual, indeterminate cleavage

Question 6

How is the cleavage in deuterostomes shaped?

Answer 6

Radial

Question 7

How is the mesoderm formed in deuterostomes?

Answer 7

Outgrowth of endodermal wall of archenteron

Question 8

How is coelem formed in deuterostomes?

Answer 8

Outpouches of archenteron

Question 9

How many species are deuterostomes?

Answer 9

~60,000

Question 10

What are the major protostome phyla?

Answer 10

arthropods, nematodes, molluscs, annelids, rotifers, platyhelminths

Question 11

During development, protostome blastopore forms ____ on the _____ end

Answer 11

mouth, anterior

Question 12

Where is the protostome nerve cord located?

Answer 12

Ventral

Question 13

What happens to protostome blastomeres and what is this called?

Answer 13

They will form into known organs early in cleavage. Determinate cleavage.

Question 14

What shape is protostome cleavage?

Answer 14

Spiral

Question 15

How is protostome mesodermal tissue formed?

Answer 15

By division of single blastomere cell

Question 16

What is a blastomere?

Answer 16

A cell formed by cleavage of a fertilized ovum

Question 17

How does the coelem originate in a protostome?

Answer 17

By splitting the mesodermal cell mass.

Question 18

About how many species are protostomes?

Answer 18

~1million.

Question 19

What are some explanations for protostomic diversity?

Answer 19

The ability to live in terrestrial environments
was a key event in the evolution of several protostome phyla. In addition, the evolution of specialized body plans provided a foundation for diversification in the most species-rich lineages of protostomes—arthropods and mollusks. In large part, the remainder of protostome evolution was driven by innovations in feeding, moving, and reproducing.