Top 10 unbelievable historical concurrencies. A zygote is a single cell which has formed as the result of the merging of an egg cell and a sperm cell. In other words, it's a fertilized egg, with the potential to develop into a living organism.
Gastrovascular system of the flatworm Dugesia, colored yellow. The gastrovascular cavity is the primary organ of digestion and circulation in two major animal phyla: the Cnidaria (including jellyfish and corals) and Platyhelminthes (flatworms). The cavity may be extensively branched into a system of canals. In cnidarians, the gastrovascular system is also known as the coelenteron, and is commonly known as a blind gut or blind sac, since food enters and waste exits through the same orifice.
Most obvious is the one from the middle with the great circular, muscular tube of the pharynx; the space around it is actually outside of the body proper. The gastrovascular cavity has a median tube in the body anterior to the pharynx; alongside and posterior to the pharynx it is divided into two lateral tubes.latworms are acoelomate, that is the outside of the gut wall is directly continuous with the mesoderm; there is no coelomic cavity and so the gut is not free inside the body. The mesoderm is muscular and is used for movement. Ectodermal cells may be ciliated and provide another means of locomotion.