Mutations and rearrangements that occur by misalignment during DNA replication are frequent sources of genetic variation in bacteria. Dislocations between a replicating strand and its template at repetitive DNA sequences underlie the mechanism of these genetic events.
Cnidarians take on two basic forms, a medusa and a polyp. The medusa form is a free-swimming structure which consists of an umbrella-shaped body (called a bell), a fringe of tentacles that hang from the edge of the bell, a mouth opening located on the underside of the bell, and a gastrovascular cavity. The mesoglea layer of the medusa body wall is thick and jelly-like.
Cnidaria. Cnidaria is a phylum of animals, which contains amazingly beautiful coral reefs, electrifying jellyfish, and many other interesting oceanic creatures. There are about 10,000 species of cnidarians and all of them are unique among all other organisms for the presence of the Cnidocytes. Cnidaria and porifera are two different phyla. â¢ Cnidarians have Cnidocytes but not the poriferans. â¢ Cnidarians have well-organized organ systems but not the poriferans; on the other hand, poriferans have an efficient tunnel system made up of pores but not the cnidarians.