Biology / Unit 10 Bio 2241 short lesson, about 20 seconds
Choanocytes and Positive Evidence for Sponge Ancestry
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The idea
A sponge's choanocytes closely resemble choanoflagellates, single-celled relatives of animals, offering positive evidence for sponges' animal ancestry beyond ruling out exclusion.
In practice
Molecular data corroborates this resemblance, consistently placing Porifera inside Animalia alongside every other animal phylum in current phylogenetic analyses.
Where people slip
"Sponges aren't really animals," per Bio 2239, isolates one missing trait while ignoring this positive evidence for their animal ancestry.
Your place on the trail
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