1. #5: Corals Are Fluorescent
You thought corals were pretty? Seen through the right filters they have a fluorescent glow. Researchers captured this fluorescent image with special camera filters in Fiji. The glowing green parts of the coral polyps are reactive zones where the coral is competing with other organisms.
2. #4: There are Coral Wars
Think coral reefs are peaceful seascapes? Forget it, many corals are engaged in long term warfare This is a coral fight! Montipora (left) battling Porites (right) for space on the reef. Space and access to sunlight are always in high demand - when 2 corals compete for the same space, they often sting each other with small stinging cells (called nematocysts) and send out mesenterial filaments and mucous. Montipora looks like it’s winning so far, but only time will tell…
3. #3 Some Coral Polyps Live Alone
So you think you understand. Corals are big structures made up of millions of tiny polyps. Wrong again. Some coral polyps don’t stack up. This Cynarina lacrymalis is only a single polyp and very rare, but it’s extremely distinctive and very beautiful.
4. #2: Some Corals Move All Day Long
When you think of coral, you probably think of a hard, jagged reef waiting to impale an unfortunate surfer. Well think again. Corals are actually colonies of tiny creatures called polyps. There are species of soft corals like this Xenia and Heteroxenia spp. that have their millions of tiny mouths pulsating all day to snag food.
5. #1: Corals Have Growth Bands Like Trees
Ever count the rings on a tree stump to find out how old it is? Well, turns out you can do that with corals too. You just need scuba gear, a pneumatic drill and specialized packing equipment that will keep a core sample alive until it can be put into a CT scanner that will visualize the bands.
The coral the scientists pictured here from the Woods Hole Oceanographic Institution (WHOI) are studying grows at about 1 - 2 cm per year. That means a growth three meters long could be nearly 300 years old.