Cnidarians

Cnidarians are a diverse group of invertebrate animals that include jellyfish, corals, sea anemones, and hydroids. They are characterized by their unique stinging cells called cnidocytes, which they use for capturing prey and defense.

Anatomy and Characteristics

Cnidarians have a simple body plan characterized by radial symmetry, a central mouth surrounded by tentacles, and a gastrovascular cavity. They do not have a true brain or central nervous system, but they do have a nerve net that allows them to sense and respond to their environment.

Life Cycle

Cnidarians have a life cycle that typically includes a polyp stage, where they are attached to a substrate, and a medusa stage, where they are free-swimming. Some species only have one of these stages, while others alternate between the two during different phases of their life cycle.

Ecological Importance

Cnidarians play a crucial role in marine ecosystems. Coral reefs, which are built by colonial cnidarians called corals, are among the most diverse and productive ecosystems on the planet. Additionally, jellyfish are important predators in the marine food web.

Study Guide

1. What are cnidocytes, and how do cnidarians use them?
2. Describe the basic body plan of cnidarians.
3. What is the difference between the polyp and medusa stages in the life cycle of cnidarians?
4. Explain the ecological importance of cnidarians in marine ecosystems.
5. Compare and contrast the different types of cnidarians, such as jellyfish, corals, and sea anemones.

[Cnidarians] Related Worksheets and Study Guides:

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