CNIDARIA

• Cnidarian sometimes called “coelenterates”.
• Cnidaria are considered "nerve-net animals“.
• cnidarians are Multicellular organisms
• cnidarian's Body is radial symmetry (no head, front, or back)
• Cnidarians Capture prey with nematocysts
• Cnidarians Have a central mouth with tentacles
• Cnidarians Lack of brain and true nerves
• Cnidarians exhibit two main body forms:

  ✓ Polyps are typically sessile and cylindrical in shape

  ✓ Medusae are free-swimming and umbrella-shaped
• Epidermis (Ectoderm)

  ✓ The outer layer of cells covering the surface of the cnidarian's body.

  ✓ It provides protection and may contain sensory structures.
• Gastrodermis (Endoderm)

  ✓ The inner layer of cells lining the gastrovascular cavity.

  ✓ Responsible for digestion and nutrient absorption.
• Mesoglea

  ✓ A jelly-like substance located between the epidermis and gastrodermis.

  ✓ Provides structural support and serves as a medium for the diffusion of gases and nutrients.
• Gastrovascular Cavity:

  ✓ A central digestive cavity with a single opening that functions as both a mouth and an anus.

  ✓ Responsible for digestion, circulation, and distribution of nutrients throughout the body.
• Mouth/Oral opening

  ✓ The opening leading into the gastrovascular cavity.

  ✓ It serves as both the entrance for food and the exit for waste.
• Tentacles

  ✓ Arm-like structures surrounding the mouth of cnidarians.

  ✓ Tentacles are equipped with cnidocytes and are used to capture prey and defend against predators.
• Cnidocytes

  ✓ Specialized cells containing stinging structures called nematocysts.

  ✓ Cnidocytes are located on the tentacles and body surface and are used for defense and capturing prey.
• Nerve net

  ✓ A decentralized network of nerve cells spread throughout the body of cnidarians.

  ✓ It allows for basic sensory perception and coordination of movement.
• Reef Protection: Coral reefs, made by cnidarians, act like natural walls, protecting coasts from big waves during storms.
• Medicine: Scientists study cnidarians to find new medicines that could help people stay healthy.
• Habitat: They make homes for lots of sea creatures, offering shelter and safety.
• Climate Help: Cnidarians take in carbon dioxide and release oxygen, which helps balance the Earth's atmosphere.
• Erosion Control: Some cnidarians help shape the ocean floor, like builders making underwater homes.