Life is everywhere in the Galapagos. It seems that just about every nook and cranny throughout the archipelago has some form of life skittering about or fluttering around. When snorkelling and floating over colourful-looking rocks covered with odd and funky textures, it’s hard to imagine that these solid objects harbour some form of life. But these “rocks” – which is actually coral in the Galapagos – are actually teeming with it! Despite their completely sedentary lives and robust exteriors, corals are alive and flourishing before your eyes with activity.
Coral in the Galapagos is of particular for snorkelers and divers because there’s two different types, and these are a fantastic example of symbiosis in the invertebrate world.
Corals in the Galapagos: A Tale of Two Organisms
Corals are in fact far distant relatives of jellyfish and sea anemones. They’re hard to see from far away, but deep within the hardened surface of corals are tiny little invertebrate creatures known as polyps. These polyps have evolved to secrete a skeleton consisting of calcium carbonate – a mineral that they extract from the water. Like spores of the ocean, the polyps drift and float around until they land on a rock and stick to it, eventually multiplying into thousands of clones.
These polyps (and the coral that forms around them) eventually become home to algae that flourish and give the corals their distinct colour. This why, when the algae die – which is otherwise known as “coral bleaching – entire patches of coral lose their distinct yellow-green colour.
Floreana and Champion Islet are great examples of this phenomenon, and have underwater sites consisting of large patches of coral “graveyards” that lost their algae a long time ago. How does the algae die, you might ask? It all has to do with temperatures.
Corals thrive between water temperatures of 24°C and 28°C (75°F and 82°F). In the Galapagos, these temperatures are seldom stable (especially during El Niño) throughout the waters, and consequently the reef-building corals aren’t as massive as anything like say, the Great Barrier Reef. You’ll often only find isolated patches of coral throughout the bottom of the sea. In the case of the coral graveyards found over in Floreana and Champion Islet, massive patches of bleached coral indicate that water temperatures were more stable at some point, which allowed for corals to flourish in massive numbers all throughout these areas.
The Two Species of Coral in the Galapagos
We’ve already mentioned the reef-building species of coral that tends to propagate on rocks and other objects on the ground. These are known as Hermatypic.
The Ahermatypic species of coral, however, does not build reefs. Instead, it ends up looking more like a plant structure that blossoms up from the seafloor and grows into an intricate and spiny cluster of skeletal bush. These types of coral also prefer colder waters and, as a result, are often found deeper in the ocean. This latter species of coral also provides shelter and a protective structure against predators for a number of juvenile fish in the Galapagos.