The outer layer of the sponge is covered by flattened cells that sometimes contract in response to potentially harmful stimuli to protect the inner cells of the sponge. One type of inner cells are , flagellated and collared cells that help circulate water through the sponge and collect food particles. Various types of cells are found in the mesohyl and may secrete structural components such as spicules or spongin fibers

One function of the poly-a tail on eukaryotic mrna sequences is to the mrna be transported from the nucleus to the cytoplasm. prokaryotic mrna also has a poly-a tail. choose the best explanation of the prokaryotic poly-a tail. a. prokaryotic poly-a tails are composed of a different molecular structure compared with eukaryotic poly-a tails. b. prokaryotic poly-a tails have the same functions as eukaryotic poly-a tails, because this process is highly conserved throughout different species. c. prokaryotic poly-a tails aren't important, because prokaryotes don't have nuclei. d. prokaryotic poly-a tails have other functions, because prokaryotes don't have nuclei.