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.
Addition: Cnidarians take their name from cnidocyte cells, most of which contain a nematocyst-a stinging cell that injects a toxin. Only Cnidarians have nematocysts. All cnidarian forms are either a sedentary polyp or a floating/free-swimming medusa.They have no excretory or respiratory system. Animals of the Phylum Cnidaria The phylum Cnidaria includes animals such as corals, jellyfish, and sea anemones. 2  All Cnidarians are aquatic and carnivorous, and they occur in two basic body shapes: polyps,â¦.