In the northern reaches of the Galápagos Islands lies Pinta, a volcanic island that accounts for less than one percent of the archipelago’s land area, yet hosts nearly one third of the native terrestrial plants.
The Enhanced Thematic Mapper Plus (ETM+) on Landsat 7 captured this natural-color image of Pinta Island on April 7, 2009. The dark pattern of old lava flows can be seen along the northern and eastern flanks of the 60-square kilometer island.
The light green ring circling the central volcanic peak shows the location of sparse deciduous forest and grassland that is suited to the harsh, dry conditions at sea level in the eastern Pacific. The darker greens, closer to the peak and crater, depict the island’s densest region of vegetation, which is fueled by moister and cooler conditions at higher elevations.
Despite some tough conditions, Pinta hosts 180 taxonomic groups of plants. Of these, 59 are only found in the Galapagos; 19 are found only on a small number of the islands; and two are endemic to Pinta. The island’s extraordinarily diverse plant population can be attributed to Pinta’s relative isolation in the archipelago; its varied climatic zones along its 2,000 foot (650 meter) peak; and the influence of the plant-eating giant tortoises that once thrived on the island.
For ages, Pinta’s isolation helped to protect it from the introduction of invasive, non-native species that can destroy plants and habitats. In the 1950s, however, fishermen introduced goats to the island. The feral goat population soared to 40,000, causing much destruction to the vegetation and the native species that feed on it. The goats were eradicated in 1990.
Galápagos tortoises are the world’s largest living turtles. They likely reached the Galápalos from South America—some 1,000 kilometers to the east—by rafting on currents. Once in the Galápagos, the turtles evolved into different subspecies as different traits were advantageous for life on the different islands.
Pirates, sailors, whalers, and settlers decimated the tortoise population by successively hunting them from the 17th century until 1959, when the Ecuadorian government made the Galápagos a national park. In 1914, herpetologist John Van Denburgh catalogued 15 subspecies of giant tortoises in the Galapagos. In 1972, the last survivor of the Pinta subspecies of giant tortoise—named Lonesome George—was moved to the Charles Darwin Research Station on Santa Cruz Island. In June 2012, George died, making the Pinta subspecies extinct and leaving the islands with just 10 subspecies of tortoise.
NASA image by Jesse Allen, Robert Simmon, and Michael Taylor, using data from the USGS Global Visualization Viewer. Caption by Laura Rocchio.