The following touches on coral bio and the harsh relationship they have with each other – Kudos to Joe Pollock for his lecture.
Coral aren’t plants nor rocks…
…They’re actually animals. Along with being able to digest small marine life, like brine shrimp, coral are also photosynthetic, thanks to their relationship with algae.
This super fun/entertaining vid does a good job highlighting the relationship.
Coral serve as homes for algae, zooxanthellae, which in turn provides energy (photosynthesis) for coral. Thus, coral & zooxanthellae have a symbiotic relationship. Along with energy, corals get their color from zooxanthellae.
Not Friends but Anemones
Coral are a highly competitive species.
Especially when in close proximity & threatened, coral will physically attack each other. They use long, microscopic stinging cells to pummel competing coral.
Here’s some great footage of coral unleashing havoc on each other. The real deal starts @ about the 1:20 mark.
Indirect competition also exists between coral. By using strategic growing patterns, coral are able to block sunlight from reaching each other. In general, coral can’t survive on a marine life diet alone.