Some cnidarians are single organisms; whereas, others are colonial. Jellyfish can reproduce either asexually, by budding, or sexually. The polyp stage is anchored to the ocean bottom. As the polyp grows, it produces saucer-shaped medusae that break away from it. These medusae swim freely and feed by catching small organisms. Jellyfish spend most of their lives as a medusa. Medusae are either male or female.