The digestive system of Cnidarians is incomplete having only one single opening which is the gastrovascular cavity the representing the anus and the mouthof the Cnidarians
The hollow body of the Cnidarian polyp which allows water through has tentacles at the top bearing cells meant for stinging
A prey caught by the tentacles is drawn in to the mouth and ingested
The Cnidarians are able to attach to surface due to their attachment adapted lower end
Human evolution is similar to every evolution in the animal and plant kingdom. Forced by the environment both internal and external forces, animals adapted to the extreme conditions they were put in. As humans evovled, bacteria and other microorganisms also evolved to better attack and obtain food from other organisms including mankind.
