Videos of pooping comb jellyfish stun evolutionary biologists:
No buts about it, the butthole is one of the finest innovations in the past 540 million years of animal evolution. The first animals that arose seem to have literally had potty mouths: Their modern-day descendants, such as sea sponges, sea anemones, and jellyfish, all lack an anus and must eat and excrete through the same hole. Once an independent exit evolved, however, animals diversified into the majority of species alive today, ranging from earthworms to humans.
I don’t want to spoil the punchline, but comb jellyfish aren’t such potty mouths – this suggests that either scientists have been wrong about jellyfish digestion, or later animals lost the trait after splitting from an ancestor which had an anus. Either way, this opens up more research areas for scientists and may further define our understanding of evolution.