Spawning and Brooding

The alternative strategy to spawning is brooding. Animals that brood release sperm into the water, while eggs remain within the mother. Sperm swim around until they find a female, enter her body, and fertilize the eggs. Eggs are brooded within the mother s body until time for them to hatch. 

Hydroids have very complex reproductive strategies. Special structures on polyps produce offspring in the medusa stage. Medusae then release eggs and sperm. Fertilized eggs develop into swimming larvae, which settle down to begin new hydrozoan colonies. 

Feather hydroids (Pennaria tiarella) form branching colonies that grow to 6 inches (15 cm). The polyps are tipped with knobby tentacles set in four or five 

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