Yesterday’s Lectures

Here’s a small part of what we heard yesterday.

To illustrate the complexity of the ecosystem of a rainforest, the Brazil nuts themselves are in a large shell that weighs several pounds and is almost impenetrable. But there is a small hole in one end that allows a species of rodent to gnaw its way in where it finds what we would recognize as Brazil nuts. The rodent eats some and buries some.  Most of the ones that are buried are never unburied but grow into new Brazil Nut trees.

Before it can make the nuts, the tree must be pollinated. This is accomplished by the females of one bee species. They are attracted to the tree by an aroma spread by the male bees but the males don’t produce the aroma themselves. The aroma comes from a species of orchids that doesn’t grow on Brazil Nut trees but grows on trees that grow nearby that the male bees like. So the other trees support the orchids and attract the male bees that spread the aroma that attracts the females that pollinate the Brazil Nuts.

And that’s where Brazil nuts come from. I’m not sure where the bees get together.

We heard earlier that most volcanoes occur on the seams where one plate is being shoved under another. That explains the Pacific Ring of Fire and about 90% of the volcanoes in the world. It doesn’t however explain Yellowstone, the Hawaiian Islands, or Easter Island. These are hot spots related to “lava plumes,” which are long fingers of lava reaching outward, into the mantle from the molten outer core. When a plume gets close enough to the crust, we have a hot spot; when they find or make a crack in the crust, we have a volcano. These typically make mountains and if the mountains are in an ocean and get tall enough, we have an island. Because the plates the make up the crust are moving, we get a sting of islands.

Today we should see land in the form of a small island, Isla Salas y Gomez, as we get closer to Easter Island. Actually, it’s the top of a volcano, no longer active because its plate has moved on from the hot spot, but you already knew that.

Because it is so isolated, it will be home to many sea birds.

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