Many metazoans (e.g., mammals, insects, earthworms) have anoxic digestive tracts that are colonized by anaerobic microbes that perform portions of digestion of food for the host. Some other metazoans (e.g., porifera/sponges) rely on intracellular digestion.
I'm wondering, which metazoan taxa (I suppose we can keep it at phyla level) host digestion that is aided by anaerobic microbes, which do not, and are there any that have digestive tracts that host aerobic microbes instead (though that seems unlikely since they'd likely completely consume the food for themselves)?
We could start by addressing a partial list of the most well described metazoan phyla (plus a few of particular interest to me). Perhaps no one will have the knowledge/expertise for each of these phyla - in which case we could have a community answer that is built on over time.
- porifera- sponges
- cnidarea - jellyfish, corals and sea animals
- platyhelminthes- flatworms
- nematoda- round worms
- rotifera- worm-like animals
- bryozoa- small aquatic animals
- brachiopoda- lamp shells
- phoronida- tubeworms
- anelida- segmented worms
- mollusca- soft bodied animals including chitons, snails
- arthropoda- insects and others with hard, segmented bodies
- echinodermata- starfish
- hemichordata- acorn worms
- chordata- primarily vertebrates
- placozoa - simplest non-parasitic multi-cellular animals
- Ctenophora - comb jellies
- tardigrada - water bears
- loricifera - tiny shelled sediment dwelling animals