Galápagos wildlife | Battle at the end of eden (multimedia)

  • Galápagos Wildlife

    Meet the cast of evolution's living laboratory 

  • Galápagos marine iguana (Amblyrhynchus cristatus)
    The world's only sea lizard, the marine iguana can grow to be 2.5 feet long. The largest of these lizards will dive down more than 80 feet to harvest algae from rocks off the ocean floor. This iguana, fresh from a mid-day meal, sports an "algae-mustache."

  • Galápagos iguanas are thought to have descended from lizards that "rafted over" from South America. A few million years of evolution has flattened their noses for optimal algae grazing, sharpened their claws to ease their daily climb from sea onto land, and strengthed their limbs, especially their powerful tails, for swimming.

  • Listed as "vulnerable" by the IUCN, marine iguanas are threatened on several islands by invasive populations of feral cats and rats.

  • Diving for food in the frigid water of the east Pacific steals the iguanas' body heat. After they scramble ashore, the lizards make their way to a sun-baked patch of sand to warm up.

  • During feeding dives, the iguanas ingest a lot of salt water. Once on land, they expel excess salt by snorting the concentrated crystals through a gland in their noses.

  • The Charles Darwin Research Station, located in Puerto Ayora on Santa Cruz Island, is dedicated to preserving the Galápagos ecosystem. Established in 1964, the station runs breeding programs for land iguanas and giant tortoises.

  • In 1972, scientists brought what they believed to be the last giant tortoise on Pinta Island to live at the station and named him "Lonesome George," (seen here a few months before he died in June, 2012). Note his saddle-shaped shell with its front arch—an adaptation that allowed Pinta tortoises to stretch their necks up to reach high vegetation in the island's dry environment. 

  • Galápagos giant tortoise (Chelonoidis nigra)
    Giant tortoises on the lusher, leafier Galápagos islands, such as the one pictured here, have dome-shaped shells that lack the adaptation.

  • For more than a century, invasive black rats, which feed on tortoise eggs and hatchlings, have prevented the giant reptiles from breeding on Pinzón island. Research Station scientists have kept the species alive, raising the tortoises in captivity until they are large enough to be "rat-proof" (~4 years of age), at which point they are repatriated.

  • In December 2012, Island Conservation, in partnership with local agencies, performed an eradication to rid Pinzón of black rats. The groups must now wait to see if the project was successful.

  • Galápagos land iguana (Conolophus subcristatus)
    Invasive goats, feral cats, and rats are the greatest threat to the archipelago's two endemic species of land iguana (the other is C. pallidus). In 1976, the Charles Darwin Research Station began a land iguana breeding program to fortify the islands' dwindling populations.

  • Blue-footed booby (Sula nebouxii)
    While this seabird isn't endemic to the Galápagos, it breeds on several of the islands, and is also quite possibly the single greatest inspiration to the archipelago's souvenir designers.

    Source: Wikipedia, Author: Pete

  • Galápagos sea lion (Zalophus wollebaeki)
    Found lounging on shores throughout the archipelago, the sea lion is often the only mammal present on islands that have no introduced species.

  • Brown pelican (Pelecanus occidentalis)
    While not endemic to the islands, the pelicans that inhabit the Galápagos exhibit the naiveté of island species. Proof of this plays out daily on Santa Cruz where pelicans hoping for scraps, boldly perch mere inches from fishermen as they clean their catch.

  • Magnificent frigatebird (Fregata magnifcens)
    Reflecting on the frigate's striking eight-foot wingspan and dexterity in flight, Charles Darwin dubbed the sea bird the "Condor of the ocean." Frigatebirds breed in the Galápagos. One can barely make out the red patch on the neck of this male bird, but when it's time to woo the ladies, the bird inflates this sac like a large red balloon for a sight that is magnificent indeed.

  • Galápagos Lava Lizard (Microlophus)
    The archipelago hosts anywhere from 7 to 9 endemic species of lava lizard. The lizard pictured here was spotted on Santa Cruz Island.

  • Galápagos finches (Geospiza, Camarhynchus, Platyspiza, Cactospiza, Certhidea)
    The 13 finch species found on the Galápagos, a.k.a. Darwin's finches, all evolved from a single ancestor.

  • The greatest difference between the finch species is the size and shape of their beaks, which correlate to the birds' primary diet (grains, insects, or cactus nectar). Finches, like the one seen here, (likely a large ground-finch), use their large beaks to extract seeds from the spiny pods of the Tribulus cistoides plant, a low-growing vine.

  • Galápagos mockingbird (Mimus parvulus)
    The archipelago's finches usually claim the glory for having spurred Darwin to his theories of natural selection and evolution. But in fact, it was the variations Darwin noted between mockingbird specimens that he collected from different islands during his 1835 visit that sparked his initial inspiration.

  • Four species of mockingbird, (in Spanish, cucuve), inhabit the Galápagos. The mockingbird seen singing here was spotted on Santa Cruz Island.

  • Prickly pear cactus (Opuntia)
    If there's one plant on which the unique wildlife of the Galápagos relies most, it's the opuntia cactus. The plant is often one of the only sources of sustenance on the arid islands; its thick, juicy pads provide both food and water to land iguanas and giant tortoises. Finches consume the cacti's seeds and flowers, and mockingbirds and iguanas, its fruit.

  • Of the more than 200 species of opuntia found in the planet's arid regions, six are endemic to the Galápagos. Only on the archipelago does the species manifest as a tree, reaching heights of nearly 40 feet, with trunks measuring more than four feet thick. The plant is thought to have evolved its tree-like form to fend against overgrazing by giant tortoises.

  • The reddish bark and inner trunk of the Opuntia echios cactus

  • Anatomy of a dried opuntia cactus pad

  • Read about the quest to save Galápagos wildlife and other threatened island species from extinction in the The Atlantic's single "Battle at the End of Eden."

The Galápagos islands have been called a living laboratory of evolution. As one of the most recently colonized places on earth, (the first permanent settlements date back just over 200 years), the archipelago still retains 95 percent of its pre-human biodiversity. With so many varied species extant, a tableau of Galápagos wildlife reveals the process of speciation at work, whether it be 13 finch species that, descending from a single ancestor, evolved different beaks to accommodate distinct diets, or a cactus that, unlike any of the more than 200 other species in its genus worldwide, evolved to assume a tree-like form to fend against overgrazing by giant tortoises. Read about the quest to save Galápagos wildlife and other threatened island species from extinction.

All photos and video by Amanda R. Martinez and Rob McGinnis unless otherwise noted