Galapagos - Science Stuff
Thu 26 Mar 2015 23:39
I’ve been meaning to write about our Galapagos experience ever since we departed weeks ago. The difficulty is how to begin since, like Dante’s Inferno, there are so many layers to consider, most of them involving lots of photos and I really can’t upload so much stuff over the satphone. What am I talking about? Well, there’s the well known stuff about Darwin and his finches, also reflected in many other species such as giant tortoises, cacti and you name it. Each island, nay, each volcano has its own collection of species separately evolved and adapted to the conditions. Very interesting but you can read about this in books. Aha, then there’s the geology. Nothing like a few volcanoes and rugged scenery of lava fields, etc. We climbed one volcano and looked down into the huge caldera full of lava from the last eruption which was only about 15 years ago. That walk also brought us into close contact with the flora, much affected by the altitude. Which is to say that as you climb up a couple of hundred metres you are confronted with a new set of plants and the fauna that go with them. Naturally this happens in other places but nowhere in my experience has such a stark contrast. For example, down at the coast (on Isabela island) it’s all lava. Nothing but lava and cactus. Most inhospitable. A bit higher up, and you are in an arid region of hardy shrubs. Hot and dusty. A bit further on and it’s lush greenery, tall trees, plentiful water and, these days, farm land, cows and everything. Then it turns damp and misty; everything covered in moss and lichen. At the top,1,000 metres, it’s almost alpine. So when Darwin talks about niches, you can see what he means: the tortoises that live at the bottom, in the arid zone, need long necks in order to eat from the bushes, while those that live higher up can find food on the ground, so they have small necks. And another thing: the cacti that grow on islands where there are tortoises have developed long, sharp thorns on their trunks, pointing downwards in order to deter the tortoises from eating them. However on islands where there are no tortoises, these thorns are absent from the cacti. Clever, eh?
What I hadn’t appreciated was how unique are the Galapagos islands when it comes to marine life. This is due to the fact that they are located at the convergence of three major ocean currents: the cold Peru current from the South, the warm El Nino current from the East, and the Equatorial Counter Current from the West. Each of these come from deep regions of the ocean but are then forced to the surface as they approach the relatively shallow waters of the Galapagos archipelago, and they bring with them all manner of sea life. Whales, sharks, turtles, tropical fish, cold water fish, pelagic fish, etc. There are lots and lots of different fish which is why the diving there is so amazing. Depending on where you jump in, the water will be warm or cold, and even in the same location, the water temperature will vary considerably at different depths. And with all those fish come the animals that like to eat them, like sea lions, boobies and other sea birds that are such a feature of the islands. So that’s why you can find penguins there, on the equator, while on a mangrove swamp nearby there are flamingos!
So the unique evolutionary equation in the Galapagos is reliant on:
- The young geological age of the islands. When created through volcanic action, they were lifeless so all the life that now exists is of “recent” origin
- Isolation. It’s miles from anywhere, therefore does not have the same variety of different animals present. For example, the islands are rich in reptiles but there are very few mammals. So the plants and animals that have managed to arrive there have had a clean sheet, so to speak, in which to make their home and to find their “niche”.
- The ocean currents, as mentioned above, which provide a vital source of food and which create a most unusual climate.
That’s the educational bit especially for any schools in Jersey that may be following the blog. Look up the details in the books. There is also a great short movie from the BBC called “Born of Fire” or something which has much better photography than anything I could do and is well worth watching. It is full of scenes where I could say “I saw that” or “I’ve been there!”
In another of our blogs I’ll tell you about how we spent our time and where we went – plus photos. But there are so many photos that I’d like to share that it may have to wait until we have a fast internet connection.