None, relies on water currents. To prevent self-fertilization, sperm and eggs are released at different times. Reproduction asexual by budding. Bud is called a bud. To prevent self-fertilization, sperm and eggs are released at different times.
Some corals exhibit mass spawning.
Tentacles containing cnidae stun and capture prey. Spp with no tentacles swallow prey as they swim. This group approaches a complete digestive tract and triploblastic development, but doesn't quite make it. Compare and contrast Cnidaria with Porifera and Ctenophora.