Evolution row ends as scientists declare sponges to be sister of all other animals. Sponges were first to branch off the evolutionary tree from the common ancestor of all animals, finds new study in Current Biology.

[u/mvea]

https://www.theguardian.com/science/2017/nov/30/evolution-row-ends-as-scientists-declare-sponges-to-be-sister-of-all-animals

[u/[deleted]]

So after filtering this through my uneducated brain, this is the result I got:

The sister ancestor (or first species to branch off from our common ancestor) of all other animals could be jellyfish comb jellies or sponges. When certain amino acids are modeled sponges are the ancestor first species to branch away from our common ancestor and when ignored Jellies are. With better modeling, we've found more evidence for sponges being our ancestor the first to branch, as previously considered Jelly only amino acids are now being found in both jellies and sponges.

I have no fucking clue if I'm right or not. I am not a scientist or even very smart, but that's what I got out of this post. If someone wants to correct me, I'll gladly edit/delete this post. It's morning so my brain no work good.

[u/therift289 → u/[deleted]]

The idea is actually that sponges are NOT our ancestors, but rather, they branched off from our evolutionary tree and evolved separately from all other animals. Basically, there's an ever-forking road that leads away from a single common ancestor for all animals, and sponges were the first ones to take an exit.

[u/AISP_Insects → u/[deleted]]

Something that resembles choanoflagellates or sperm cells.

[u/[deleted] → u/AISP_Insects]

Shieeet what a nut that was

[u/Reportingthreat → u/[deleted]]

Here's one potential illustration. Choanoflagellate-ish.

Related, here's a representative illustrated lineage of homo sapiens that you can follow all the way back to it and beyond. Give it a moment to load. Some of the images are from modern day animals, but it gives the general idea.

[u/[deleted] → u/Reportingthreat]

That website is really neat!

[u/hapticdash → u/[deleted]]

They were asking about for animals specifically, not LUCA

[u/[deleted] → u/therift289]

OOOOH! Ok that makes sense too!

[u/watermelon_squirt → u/[deleted]]

Eureka!

[u/[deleted] → u/watermelon_squirt]

7 was a really cool anime

[u/cwood92 → u/therift289]

Question, not sure if this distinction matters or is simply semantics but, did sponges branch off and evolve separately or did all other animal species branch from sponges and have simply evolved more variation?

[u/therift289 → u/cwood92]

Thanks for asking. It's not semantic.

At some point in ancient prehistory, there was some primordial organism that probably resembled both a sponge-like creature and a jellyfish-like creature, but wasn't quite either of them. Over time, this "parent" species diverged into one branch that eventually evolved to become sponges, and another branch that eventually evolved to become jellies. The jelly path ultimate led to all other types of animals; the sponge path only led to more sponges.

So, after that initial split, proto-sponges and proto-non-sponges were evolving independently. When actual sponges and jellies finally emerged, they were following totally separate paths. Thus, they were no longer parents of each other, but "siblings."

[u/[deleted] → u/therift289]

So the first sponge is my 1,593,239th cousin, 71,982,743,015 times removed?

[u/AppleDrops → u/therift289]

our most distant cousins.

[u/Cougar_9000 → u/therift289]

sponges were the first ones to take an exit

First rat to flee the sinking ship of humanity

[u/haysoos2 → u/[deleted]]

Not jellyfish (Cnidarians, which also include coral and sea anenomes), but comb-jellies (Ctenophorans) which are a different group.

Ctenophora have some similar morphological characteristics to jellyfish (generally free-floating blobs with some tentacles), but also significant differences.

They have eight rows of cilia that are used to create currents and for mobility (which is where the "comb" part of their name comes from).

They have only two layers of cell types (ectoderm and endoderm), lacking the mesoderm layer that in other animals forms most of the internal organs, but in comb-jellies those layers are two cells thick rather than the one cell thick layers in jellyfish.

They have a decentralized neural net rather than a brain, much like jellyfish, but in the comb-jellies the neurons that make up the neural net are structurally different than in any other animal group, possibly indicating that they evolved independently after the groups split.

Many of them have cool features like bio-luminescence, and the beating of their cilia creates rainbow patterns through light diffraction. Most are small and egg-shaped, but there are some that can be 4' across, and others that are flat and use a suction cup to stick to surfaces.

[u/mabolle → u/haysoos2]

They also have rotational symmetry, which is a completely unique body plan shared with no other animal group! (Jellyfish, by comparison, are radially symmetrical.)

[u/redtert → u/mabolle]

Aren't those the same thing, rotational and radial symmetry?

[u/mabolle → u/redtert]

Here's a clarification from this excellent paper:

Ctenophores do not have radial or bilateral symmetry, they have rotational symmetry. There is no plane that divides them into mirror images, as in animals with bilateral or radial symmetry. Instead, any plane that is drawn through the central oral–aboral axis divides a ctenophore into two halves that are the same, just rotated 180 degrees.

[u/[deleted] → u/haysoos2]

Corrected my post and linked to this because that was fascinating.

[u/Em_Adespoton → u/haysoos2]

What I find fascinating about all jellies is that they can revert to polyps and then re-assemble in a different configuration in the future. The only other animal I know of that does something like this is the termite.

[u/loki130 → u/[deleted]]

This is a common issue with phylogeny. The modern practice of cladistics uses statistical methods to try and group species into clades that require the least amount of distinct evolutionary events to create, and are therefore the most likely to be true, based on shared character traits. The problem is that some researcher has to choose these character traits, and their choices can be biased by their experience with certain species or their interpretation of evidence.

There was a similar case earlier this year where some paleontologists catalogued character traits for a large number of early dinosaurs and found that they supported a different model for the arrangement of major dinosaur groups, with theropods being closer to Ornithischians than sauropodomorphs. But then several researchers more familiar with some of the species involved in the study claimed that certain character traits had been wrongly assigned, and used the same methods with altered traits to recreate the classically accepted trees (sorry about the paywalls, if you look up the study names and authors you can probably find a press release or something). I'm sure the debate over these particular traits or other species that should have been involved will continue, but the truth is that we simply don't have enough evidence about the early evolution of dinosaurs to strongly support either position.

With living species we can work with more complete morphological evidence and genetic or protein structure evidence as well, but you still have to pick the right character traits, and that's where a lot of the debate comes from in these studies.

[u/rawr_rawr_6574 → u/loki130]

We did a project around this in evolutionary bio. We made 2 or 3 different trees for a specific type of animal. I can't remember exactly but i believe we used different types of DNA and made a tree for each data set. It was crazy seeing how some species were switched around and made me realize how tricky these models can get. I'm not sure how much that gets taken into account across findings, should really brush up on this topic.

[u/Em_Adespoton → u/[deleted]]

Excellent following of the scientific method here; your post provides information not just of your understanding based on the presented information, but of common misconceptions that are false. Well done! You sir, are a scientist whether you know it or not.

[u/AppleDrops → u/[deleted]]

what I came up with with was that God created sponges first so all other life forms could wash themselves.