Ch. 44 Early Animal Evolution and Diversity

Question 1

the life cycle of animals is dominated by the ____ stage

Answer 1

diploid

Question 2

animals are ___, _____ eukaryotes that lack ____

Answer 2

animals are multicellular heterotrophic eukaryotes that lack cell walls

Question 3

plantae, fungi, and animalia _____ evolved from single celled eukaryotes

Answer 3

separately

Question 4

how many species of animals have been described?

how many are estimated to exist?

Answer 4

1.5 million described

estimated 5-30 million exist

Question 5

eukarya includes both ____ and ____ organisms

Answer 5

single celled and multicelled

Question 6

eukarya is a _____ taxon with multiple ____ of cell structure

Answer 6

eukarya is a monophyletic taxon with multiple synapomorphies of cell structure

Question 7

animalia is ______

what are the two major groups within animalia?

Answer 7

monophyletic
-molecular and structural characters and common features support the common evolutionary history of all animals

animalia can be unicellular or multiclelular

1. protozoa (single celled)
2. metazoa (multicelled, can be vertebrates or invertebrates)

Question 8

what major group of eukaryotes do animals belong to?

Answer 8

unikonta

Question 9

what are the animals’ closest ancestor? what type of organism are they?

Answer 9

choanoflagellates are the closest ancestor to animals

• eukaryotic (protist)
• “sister taxon” relationship

Question 10

what is a Metazoan?

Answer 10

all animals having the body composed of cells differentiated into tissues and organs and usually a digestive cavity lined with specialized cells

means “after animal”

Question 11

when did the metazoa originate?

Answer 11

1 billion to 575 million years ago (Proterozoic)

Question 12

where did early evolution occur?

Answer 12

entirely in the ocean

Question 13

how many phyla are within the metazoa?

Answer 13

35

Question 14

what are the most basal metazoans?

Answer 14

sponges (in group porifera)

Question 15

what are the two subkingdoms of metazoa?

Answer 15

parazoa (have no gut, cellular grade of complexity)

eumetazoa (have a gut, tissue grade of complexity)

Question 16

what groups fall within the parazoa? what is the definition of a parazoan?

Answer 16

1. porifera (sponge)
2. placozoa (flat disk animal)

• parazoans represent the lineage closest to Protists, the multicultural organisms that gave rise to the animal kingdom
• most basal metazoans

Question 17

parazoan characteristics (sponges)

Answer 17

-Sponge bodies lack organized tissues and guts – multiple cell types scattered throughout a sponge body
• Mostly marine with a few freshwater species
• Suspension feeders
• Benthic (bottom-dwelling)
• Specialized cell types (food collection, skeletal secretion, etc.)
• Lack organized tissues
• They come in a wide variety of body forms – Some are vase-shaped & hollow in the center – Some are full of chambers and passages – Fans, globes, etc.

Question 18

what groups fall within the eumatazoans?

Answer 18

cnidarians (diploblastic)

bilaterians (triploblastic, bilaterally symmetric metazoans)

Question 19

what does eumetazoa mean? what are their basic characteristics?

Answer 19

Eumetazoa means “good animals” – Eumetazoa have tissues, are diploblastic or triploblastic – Eumetazoa are radially or bilaterally symmetric

Question 20

metazoan phylogeny is based on ______

Answer 20

body plan