I have experience polyp bailout on hammers but as a stress response and they were not propagating. Is the release of planulae the same as polyp bailout?
https://aquarium.org/animals/pocillopora-coral/
Yes, some corals of the family Euphyllidae are known to undergo polyp bailout as well. This is indeed primarily a stress response.
The release of planulae is something that healthy corals will do. As a whole, there are three main ways that corals create new colonies - fragmentation (I'm counting both polyp bailout and the thing fungiidae do when they die and produce many colonies under this), broadcast spawning, and brooding (planulae release).
Fragmentation is what the name suggests, the coral gets fragmented or fragments itself in some manner.
Broadcast spawning is where corals use external cues to all sync up and spawn together all at once. Each coral releases bundles of eggs and sperm that mix together. Fertilized eggs will eventually develop into free swimmers called planulae that find a part of the reef and settle. This usually occurs once or twice a year for most coral species.
Brooding is when the coral develops the eggs inside of the polyp and releases them fully formed. Think how mammals give birth, but other animals lay eggs. Some species will capture sperm in the water column from other colonies, and some other species will just continuously release clones of themself. Quite a few genera are documented to do this, but it is usually not widespread among the corals that people like to keep in reef aquaria.
The main reason why
Pocillopora can be annoying is because the species that are known to brood do so every month when conditions are right.
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