The Origin Of the Galapagos Islands

By: Eric Castro
The Galapagos Islands rise in the Platform Tortoises, a basaltic submarine plateau located between 360 and 900 meters under the surface of the ocean.

It is an entirely volcanic archipelago, and only the Isabela islands formed by 6 side volcanos to side, of those which five are active.

The Galapagos Islands are classified as a "hot spot" that is an area of high thermal flow and of an intense seismic and volcanic activity, subject to varied annual eruptions.

The archipelago is in the badge of it is born, fair in the limit with the badge Coconuts, what has explained that the islands of the East are older than the western one. When being formed an island after an eruption, the badge would have moved toward the East (together with the island), and then the Galapagos Islands would have been formed a new Galapagos island with another eruption, the which it would be located to the West of the previous one, and so forth.

This way, the oldest islands would have originated about 5 millions ago of, while the newest would only be 700.000 years old   The first observation when thinking of oceanic islands, is that in its origin life didn't exist in any form on them. The great distance between the islands and the continent makes very difficult for the terrestrial organisms to arrive to them, still having good dispersion methods.

Logically, you plant and animals with good dispersion strategies, have bigger possibilities to arrive at the islands and to colonize them if the conditions are favorable. The consequence of this phenomenon, is a flora and fauna not balanced in comparison with the continent. The word " disharmonic " is used to define this condition, being the Galapagos Islands a good example of this. An example of it, is that the vertebrates are very represented by birds and reptiles, however, the native mammals are barely represented, while the amphibians and fish are completely absent.

Anyone of the species here present, in some moment had to cross more than 1.000 Km. of ocean and theoretically this could only have been made in three ways: floating in the sea or in a natural raft; dispersed by the wind or flying; or transported in the body of another organism, for air or for sea.

In the transport for the water, the seeds of many plants could be dragged floating in the surface of the water, as well as the turtles can float since they have a " pocket " with air between the shell and the body. Likewise some natural rafts as trunks of trees could have transported the first insects and also some reptiles.

In the transport air, many insects have been drag by big currents air, as well as many seeds that can resist low temperatures. The drop representation of butterflies in the islands is because its wings are very fragile and the very sensitive larvas.

The voyage in other organisms is carried out, in general, for birds that bring seeds in its stomaches, among its feathers or in the paws. Of the 607 species of plants that exist in the Galapagos Islands, at least 59% was transported as seeds by birds, 32% for the wind, and 9% for the ocean, without considering the species introduced by the man.

Once in the islands, each organism should find a sustrato and nutrients to survive. The establishment is vital to colonize the island with success.

After the organisms have been possible to settle down, they should reproduce to assure the survival of the species. The hermaphrodite organisms, have an advantage in this aspect, since they should not find a complementary individual of their same species to reproduce.

Finally, the herbivores should find plants to feed, therefore, the plants should have been seated before the animals.

After they go arriving the species, each one goes occupying a niche that is not available. Many times competition can take place species that arrive at the island between two; in such a case, one of two o'clock will adapt to occupy another nicheFind Article, or one will extinguish. The Galapagos islands reaches a balance when the immigration is balanced with the extinction.

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