The Phylum Cnidaria
The Phylum Cnidaria includes such diverse forms as jellyfish, hydra, sea anemones, and corals. Cnidarians are biracial symmetric. In simpler terms, Cnidarian bodies are simple and predictive, primitive of a sort. Cnidarian bodies have two or sometimes three layers. A gastro vascular cavity that has a single exterior opening that serves as both mouth and anus. Often tentacles surround the opening. Some cells are organized into two simple nerve nets, one epidermal and the other gastro dermal, that help coordinate muscular and sensory functions.
Cnidarians have two basic body forms, medusa and polyp. Medusa, such as adult jellyfish, are floating. They usually have umbrella-shaped bodies and four-part symmetry. The mouth is usually on the underside, and the tentacles originate on the rim of the umbrella.
Polyp on the other hand are rod shaoe moving organisims. Such as coral, sea cucumbers, and anemones. Unlike medusa polyps control their movements and gather food involentarly.
Cnidarians have two basic body forms, medusa and polyp. Medusa, such as adult jellyfish, are floating. They usually have umbrella-shaped bodies and four-part symmetry. The mouth is usually on the underside, and the tentacles originate on the rim of the umbrella.
Polyp on the other hand are rod shaoe moving organisims. Such as coral, sea cucumbers, and anemones. Unlike medusa polyps control their movements and gather food involentarly.