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.
The ventral cavity includes the thoracic and abdominopelvic cavities and their subdivisions. The dorsal cavity includes the cranial and spinal cavities. 1  The cranial cavity is a large, bean-shaped cavity filling most of the upper skull where the brain is located.2  The vertebral cavity is a very narrow, thread-like cavity running from the cranial cavity down the entire length of the spinal cord.he cavities include: 1  Dorsal body cavity. 2  cranial cavity, enclosed by the skull and contains the brain. 3  spinal canal, enclosed by the spine and contains the spinal cord.