Some of the smaller poripinnans will grow smaller and begin to lodge themselves parasitically in the pores of larger filter-feeding creatures, such as Zanzetukhan's. They will filter out food which would have been pumped into the larger organism.
First parasites there! good job! *Achievement get*
Viruses are technically parasites...
Thanks, though.
Meanwhile, some of the deep-sea poripinnans[/b] (I thought the poripinnans were monophyletic?) will develop a type of cell which takes note of the chemicals being pumped through the water, as well as cells which form a better intercell communication pathway. In short, a primitive nose and very primitive nerves. Call these new creatures rhinasusans.
At the size the actual organism are, specialized cells for communication are not really useful. Increasing the general cellular communication would be enough.
I had imagined the poripinnans as being
at least a millimeter or so...um, GM, can we get an update on sizes?
Finally, because those primordial-soup prokaryotes haven't been getting much love lately, some of the eukaryotic creatures of the aforementioned lineage will absorb some of the related poisonous ones, causing the latter to become poison-producing organelles.
Now this is new. Nowhere on earth there is "poisonous organelles". Poison is usually produced the same way as regular proteins. That would be a secondary, specialized protein "factory", something truly alien. It is perhaps less efficient than the regular way, though.
I'd imagine that an organelle which devoted itself entirely to producing one or a few proteins or whatever would actually be MORE efficient than a cell making its own.