This hydrozoan has washed up on a beach. It is called the Portuguese Man of War and has a medusa body form.

• Hydrozoans can spend part of their lives in the medusa body form and part of their lives in the polyp form, but they usually spend longer periods in just one form. 
  
• The fresh water Hydra, which is a hydrozoan, lives its life entirely in the polyp form. 
  
• Another hydrozoan, the spine-chilling Portuguese Man of War, with tentacles that can dangle down to as far as 165 feet, lives its life mostly in the medusa form.

This hydrozoan is attached to a plant. It is called the Hydra and has a polyp body form.

• Most hydrozoans begin their lives as a polyp. 
  
• The polyp can reproduce asexually by budding. The detached bud grows into a medusa form. 
  
• The adult medusas release eggs and sperm in the water. The eggs become fertilized and the zygote eventually develops into a planula, which is a young polyp. 
  
• The planula plants itself to a firm surface to grow into an adult polyp, starting the cycle all over again.

Scyphozoa

• Scyphozoans include the animals referred to as true jellyfish, such as the animal pictured. 

• The name Scyphozoa comes from the Greek word Skyphos for cup and zoia for animal, thus the name means "cup animal." 
  
• All scyphozoans are active predators that live out the majority of their lives in the medusa stage. 
  
• They range in size from as small as your fingernail to as large as a small car.

Scyphozoa Reproduction

• Most scyphozoans begin their lives as a polyp. The polyp can reproduce asexually by budding. The detached bud grows into a medusa form, which is the form that most scyphozoans remain in for the rest of their lives. 
  
• The adult medusas release eggs and sperm in the water. The eggs become fertilized and the zygote becomes a planula. 
  
• The planula plants itself to a firm surface to grow into a very short-lived adult polyp, starting the cycle all over again.  
  
• Most scyphozoans spend most of their lives as a medusa.

Anthozoa

• The word Anthozoa comes from the Greek word Anthos for flower and zoia for animal, thus anthozoans are "Flower Animals." 
  
• Anthozoans are strictly polyps, including the brightly colored corals and sea anemones, such as the one pictured.

Anthozoan Reproduction

• Anthozoans remain in polyp form their entire life. 
  
•  The polyp can reproduce asexually through budding.  
  
• The polyps can also reproduce sexually by releasing egg and sperm that combine to form a zygote that then develops into a planula.  
  
• The planula lands and settles in place to grow into an adult polyp.