AnswerThese are the enterocoelomates.Starfish, sea urchins are examples.Generally animals of the phyla annelida, molluscs and anthropoda belong to this group.
They are animals formed by enterocoely; in which the mesoderm arises from the wall of the embryonic gut archentron. The latter is an hollow outgrowth which forms the coelom.It is the type of coelom found in deuterostome animals.
Explanation:
It is a virus; they are not a type of cell
It contracts and is pulled downwards
The endosymbiotic theory states that eukaryotic cells might have evolved from prokaryotic cells through a close realtionship.