Primary succession is the colonization of living organisms into an area that was not previously colonized by any living things. A Secondary succession is the regeneration of the living community after a major disturbance.
It is chemical because of the heat and gas which causes air bubbles
Triggerfish and hawks fish. They have depressed body shape and their tail is diphycercal. Their tail shape gives them manoeuvrability and their body shape allows them to fit into small places on the reefs which makes them good for adaptations.
Shark fish; they have fusiform body shape and heterocercal tail shape and their good adaptation help them to be top predators and need speed to hunt down their animal.
Stingray; they have depressed body shape and diphycercal tail shape. Their good adaptation helps them to timid fish who feed and hide along the bottom.