Stupid thread spinoff: major animal division free-for-all

Inspired by the recent animal uprising thead, I got to thinking about what would happen if the major groups of animals all went at it in some kind of ecological battle royale.

Trouble is, my knowledge of evolutionary biology is rusty and the tree of life suggests that making factions based on evolutionary relationships would be extremely complicated. Still, I’ll try my best.

The first group will consist of everything but the bilaterals, ie sponges, comb jellies, and cnidarians.

The second group will consist of the lophotrochozoa, as represented by molluscs, brachiopods, and annelids (earthworms and leeches).

The third will be that group without clear evolutionary relationships, like the rotifers and flatworms. Those two will lead this “maverick” faction.

The arthropod arm of the ecydosozoans makes up the fourth group. As such it’s bugs and crustaceans representing water bears and velvet worms.

The fifth group is the remainder of the ecydosozoa–the nematodes and such.

Group 6 is the echinoderms and hemichordates: acorn worms, sea urchins, starfish, etc. I’ll also put the invertebrate chordates here, like hagfish and lancelets.

Group 7 will be comprised of fish, jawed or otherwise.

Group 8 gets the reptilians: birds, turtles, crocodiles, and lizards. I’ll put the amphibians in here too, since I suspect they’d be screwed by themselves.

Group 9 is everything else up the tree; essentially, mammals.

Assume that these factions can only attack each other directly; no taking out plants to starve one group, for example. Who wins?

The answer: nobody. But for the sake of nerdy fun, who do you think would ultimately dominate Earth before the ecosystem collapsed?

I’d say mammals have the biggest advantage because of their positions in the food chain, relative intelligence, and inclusion of humans in the group. But if we add the condition that fighting only happens in chance encounters as everything goes about its day to day business, I see mammals driven out of the ocean and confined to the land’s surface. But I don’t see anything except maybe arthropods even remotely posing a threat up there.

1, 3, and 6 are pretty much screwed. 5 will last only because of C. elegans, and that’s only because of their sheer numbers.