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Cnidarian Characteristics

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Hydrozoa Facts and Classification
Flower Hat Jelly (Olindias formosa).

Flower Hat Jelly (Olindias formosa).

Photo © Fred Hsu / Wikipedia.

The Class Hydrozoa includes about 2,700 species. Many hydrozoa are very small and have a plant-like appearance. Members of this group include the hydra and the portuguese man-o-war.

  • Order Actinulida
  • Order Hydroida
  • Order Hydrocorallina
  • Order Siphonophora
  • Order Trachylina
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