Comb jellies proven to be the sibling group to all other animals
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The sponges have developed their own way of life, where the adults are immobile and fixed and they feed by filtering the water, like many other groups of animals, for instance clams or sea squirts.
All such groups of sessile filtering animals have greatly simplified bodies and very reduced nervous systems.
Because the ancestor of the sponges was already much simpler than the ancestor of clams or of sea squirts, they are the simplest of all.
While sponges do not have neurons, they have most of the genes required by neurons and there are good chances that the ancestor of the sponges had neurons.
The fact that sponges are more closely related to humans than comb jellies is exactly analogous to the fact that the sea squirts are more closely related to humans than the lancelets.
While both comb jellies and lancelets appear more similar to humans than, respectively, sponges and sea squirts, that is only because both sponges and sea squirts are simplified due to their sessile water-filtering way of life.
Yes, as the joke goes, as the larva of an anemone settles into its permanent feeding spot it will consume its own brain, much like the professor that has finally achieved tenure.
Could actually be.., perhaps I am miss-remembering :)
Tunicates and Echinoderms seem to have evolved from bilateral ancestors like the ancestors of chordates.
If anybody wants to go looking: https://royalsocietypublishing.org/doi/10.1098/rstb.2015.047...
Compare also https://slatestarcodex.com/2016/11/17/the-alzheimer-photo/
[0] Any domain where deep learning is applicable.
They studied exactly two sponges and two comb jellies.
Perhaps there's a microscopic organism, or a sea squirt or something as yet unclassified in the ocean.
But for now, cousin Comb Jelly takes the crown!
This thing has the coolest warp bubble I've seen.
Wish I knew more about biology. I tried a couple of introductory molecular biology lectures and while I found them very interesting, both times I started feeling quite lost by the 3rd hour. So much chemistry and physics to learn. I wish I was smarter and better educated
If this stuff interests you I would like to recommend Dawkins' 'The Ancestor's Tale', it is pretty accessible and walks you back through time step-by-step.
See https://en.wikipedia.org/wiki/Last_universal_common_ancestor for more info:
> The LUCA is not the first life on Earth; it may have lived among a diversity of other organisms whose descendants all died out. Rather LUCA is the most recent form from which all surviving life on Earth is descended.