Flashcards in Ch. 44 Early Animal Evolution and Diversity Deck (20):
the life cycle of animals is dominated by the ____ stage
animals are ___, _____ eukaryotes that lack ____
animals are multicellular heterotrophic eukaryotes that lack cell walls
plantae, fungi, and animalia _____ evolved from single celled eukaryotes
how many species of animals have been described?
how many are estimated to exist?
1.5 million described
estimated 5-30 million exist
eukarya includes both ____ and ____ organisms
single celled and multicelled
eukarya is a _____ taxon with multiple ____ of cell structure
eukarya is a monophyletic taxon with multiple synapomorphies of cell structure
animalia is ______
what are the two major groups within animalia?
-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)
what major group of eukaryotes do animals belong to?
what are the animals' closest ancestor? what type of organism are they?
choanoflagellates are the closest ancestor to animals
-"sister taxon" relationship
what is a Metazoan?
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"
when did the metazoa originate?
1 billion to 575 million years ago (Proterozoic)
where did early evolution occur?
entirely in the ocean
how many phyla are within the metazoa?
what are the most basal metazoans?
sponges (in group porifera)
what are the two subkingdoms of metazoa?
parazoa (have no gut, cellular grade of complexity)
eumetazoa (have a gut, tissue grade of complexity)
what groups fall within the parazoa? what is the definition of a parazoan?
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
parazoan characteristics (sponges)
-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.
what groups fall within the eumatazoans?
bilaterians (triploblastic, bilaterally symmetric metazoans)
what does eumetazoa mean? what are their basic characteristics?
Eumetazoa means “good animals” – Eumetazoa have tissues, are diploblastic or triploblastic – Eumetazoa are radially or bilaterally symmetric