Jellyfish Dissection Lab:
Domain Eukarya
Kingdom Animalia Phylum Cnidaria Procedure:
Ecology of Cnidarians: The distribution of corals in the world is determined by the environment’s temperature, water depth, and light intensity. Stony and hard corals require high levels of light because they rely on mutualistic relationships with algae that capture solar energy. These relationships allow coral reefs to live in water that carries few nutrients. Corals suffer from the use of chemical fertilizers, insecticides, and industrial pollutants. Overfishing can also upset the ecological balance of coral reefs. Many corals have died from bleaching, which is caused by rising ocean temperatures.
Groups of Cnidarians: Cnidarians include jellyfishes, hydras and their relatives, and sea anemones and corals. Jellyfish are part of the class Scyphozoa. Scyphozoa means “cup animals.” Scyphozoa live their lives primarily in their medusa stage. The polyp form of jellyfish is restricted. They live in a small larval stage and never form any elaborate colonies. Jellyfishes can be quite large, the largest ever found was 4 meters in diameter and its tentacles were over 30 meters long. Hydras and their relatives are part of the call Hydrozoa. Jellyfish reproduce sexually. The polyps grow in branching colonies that sometimes extend more than a meter. Polyps are specialized to perform different functions within their colonies. The most common hydrozoan living in fresh water are hydras. Hydras lack a medusa stage. They reproduce asexually. Hydras get their nutrients from the symbiotic photosynthetic protists that line in their tissues or by capturing, stinging, and digesting small prey. Sea anemones and corals are part of the class anthozoa. All anthozoa have a central body surrounded by tentacles. Most species are comprised of many individual polyps that make up a colony. Sea anemones live at all depths of the ocean, They use nematocysts to catch a variety of marine organisms. Many shallow-water species also depend on nutrition from photosynthetic symbionts. Individual coral polyps look like miniature sea anemones, though coral grows in large numbers forming colonies. The colonies grow slowly and may live for hundreds or even thousands of years. Having many coral colonies near each other creates beautiful coral reefs. Anthozoans reproduce sexually. |