It has a single layer of cell.
Lay a paper on a flat surface. With your hands on the surface, push two sides together until you make something that looks like a polyp. Voila! Something similar to a crosssection of a sponge. Think of the paper as cells in a single line.
Sponges lack muscle cells for movement, while cnidarians lack a skeletal structure for support and protection. Without these features, these organisms are limited in their ability to achieve a more mobile lifestyle compared to animals with more specialized adaptations.
Just finshed it on a test. Sponges lack a digestive track, symmertical plan, and nerce cells.
Ban'n chen, al fe research.
A primitive animal is a type of organism that is considered to be simple in structure and function compared to more complex organisms. These animals often exhibit features that are similar to ancestral forms, reflecting an earlier stage of evolution. Examples of primitive animals include sponges and jellyfish.
Sponges are less complex because they are just made of individual cells. There is no level of organization past cells in sponges. Cnidarians, on the other hand, have tissues, a higher level of organization. Tissues allow for some forms, like box jelly fish, to have eyes (this is just one of many advantages of tissues). Cnidarians' level of organization stops there though, they have no organs (heart, brain, etc.).
Jellyfish are cnidarians.
The comparative form of "primitive" is "more primitive."
Cnidarians are a phyla in the kingdom Animalia, and more specifically, the subkingdom Eumetazoa.
The nervous system. Cnidarians have a neural net, but porifera do not.
There are many organism with a forelimb with the most primitive trait. These animals include certain species of monkey animals.
Primitive has a base in the word "Primate", so something that is more primitive is something more unsophisticated or savage.
The most "primitive" protist in the Kingdom Protista would be the more ancestral protists. One major group of protists called the Excavates (which include the Diplomonads and the Parabasalids) are considered by some scientists as the most "primitive" because it lacks a mitochondria while other protists have mitochondria.