- The diagram illustrates the anatomy of Cnidaria, a phylum that includes jellyfishes, sea anemones, corals, and hydras.
- All cnidarians share a common body plan with two tissue layers: the outer epidermis and the inner gastrodermis, separated by a gelatinous mesoglea.
- They possess a gastrovascular cavity that serves for both digestion and distribution of nutrients, with a single opening functioning as both mouth and anus.
- Cnidarians are equipped with specialized stinging cells called nematocysts, located on their tentacles, which are used for capturing prey and defense. These cells contain coiled threads that can be discharged to inject toxins.
- Two main body forms exist in the cnidarian life cycle: the sessile polyp stage (seen in anemones, corals, and hydras) and the free-swimming medusa stage (characteristic of jellyfishes).
- A nerve net provides a decentralized nervous system for coordinating movement and responses to stimuli.
- The cross-section of a tentacle shows the arrangement of epidermis, mesoglea, muscle fibers, nerve net, and gastrodermis, highlighting the structural simplicity yet functional efficiency of these organisms.
Parent Tip: Review the logic above to help your child master the concept of cnidaria worksheet.
