Phylum Cnidaria / Coelenterata and Body Wall and Gastrovascular Cavity of Cnidaria -
Body Wall and Gastrovascular Cavity of Cnidaria:
- The coelenterates show blind sac type of body plan.
- There is a central digestive gastrovascular cavity or coelenteron with a single opening that serves as both the entry and exit for material.
- This cavity is surrounded by the body wall that shows the following layers:
- The outer epidermis derived from the ectoderm. It consists of epitheliomuscular cells and cnidocytes. They provide covering and perform muscular contraction.
- The inner gastrodermis derived from the endoderm. It surrounds the gastrovascular cavity. It consists of nutritive-muscular cells, gland cells and interstitial cells. Gonads are also derived from the cells of gastrodermis.
- The middle layer is non-cellular and gelatinous. It is called the mesoglea. It forms the skeleton of cnidarians.
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The middle layer is noncellular and gelatinous. It is called the mesoglea. It forms the
skeleton of cnidarians.
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