While the land environment of Galapagos appears harsh, characterised by parched, rocky desert-like terrain, the islands support several species of land animals and birds. About a quarter of all plant species and nearly all of the reptiles found here are endemic, species that are found nowhere else and have adapted to the harsh environment of the Galapagos Islands.
This environment has, however, limited species diversity while creating a delicate balance between species. Some are completely dependent on others, both plant and animal. While there is some speculation that at one time (millions of years ago) a land bridge from Costa Rica to the Galapagos may have existed, the islands probably were never connected to the mainland. Thus the species that exist here could only arrive through flight or by floating to the islands on large, floating areas of vegetation washed down by South American rivers. Seeds and insects were perhaps brought from the continent by high winds; birds also could have carried seeds with them to the islands. The lack of large mammals or amphibians prior to the arrival of man is explained by the problem of arrival—they simply were not suited for the journey.
The Galapagos Islands have four primary ecosystems, formed by climate patterns and differences in elevation. The lowlands, generally arid areas with forests of cactus, comprise the first ecosystem. Moving upwards in elevation, the next system is subtropical forests, and the third is more humid, dense forests. The fourth consists of primarily ferns and grasses at the highest elevations. Only the largest islands, such as Isabella, contain all four systems.
The Galapagos Islands are situated at the confluence of several ocean currents, which not only helps account for the mild climate in the islands, but also its remarkable diversity of beautiful marine life. The cold, salty Humboldt Current runs northward along the South American coast from the Antarctic, turning westward near the equator bringing cool waters to the islands. The warm, less saline Panama current, runs southward along the coast of Central America turning westward near the equator. The cool Southern Equatorial Current runs westward, continuing with the energy of the Humboldt. Deep below the ocean surface, the Equatorial Countercurrent (also known as the Cromwell) runs from the west towards the islands, and is diverted upwards by the western islands, bringing cool, nutrient rich waters from the deep ocean to the island region.
The variation in the underwater landscape, including underwater volcanoes rising nearly to the surface, adds to the diversity found here. Over 2900 marine species have been identified in the area, and about 18% of these are found nowhere else.
Many species on the Galapagos are found nowhere else. Having developed and lived in isolation from humans, most species found there are nearly fearless of humans, and can be approached at close range. Below are some of the species unique to the Galapagos islands:
Galapagos Sea Lions
One of the most playful and entertaining animals of the Galapagos, they often will swim with visitors at the beaches of Galapagos. Found throughout the Galapagos islands, they have also formed a colony on Isla de la Plata just off the coast of Ecuador. They feed primarily on sardines, and can travel several kilometers off the coast to search for food. Their major predators are sharks and killer whales; sea lions often carry scars from battles at sea.
The social and inquisitive nature of the Galapagos sea lions makes them highly vulnerable to human activity. They willingly approach areas inhabited by humans, bringing them into contact with human waste, fishing nets and hooks which can do serious harm to the animals.
Galapagos Fur Seal
Much smaller than the Galapagos Sea lion, they have a thicker fur coat revealing their ancestry to the colder southern coasts of Peru and Chile. They were heavily hunted during the 19th century, when demand in Europe and the US for their pelts was high, and nearly brought to extinction. Today, they have recovered, with a total population of about 30 to 40 thousand on the islands of Pinta, Marchena, Santiago, Isabela and Fernandina.
Bats and rats
The islands are also home to two endemic species of bats, and two of the seven original species of rice rats. The other species of rice rat are now extinct, due primarily to the arrival of the Norwegian Black Rat brought to the islands on visiting ships.
The Galapagos Giant Tortoise is the largest of the living tortoises, reaching weights of over 400 kg (880 lbs), and with lifespans reaching over 100 years. At the time of their discovery in the 16th century, there were probably around 250,000 tortoises representing 15 subspecies on the islands. Today, there are only 10 subspecies remaining, and a population of about 20,000. Lonesome George, the most famous of the Galapagos tortoises and the last surviving member of the Pinta species, passed away in 2012. Previously hunted for their meat, their unique ability to stay alive on ships for months without food or water greatly affected their numbers. Introduced species have further reduced their population; some are direct predators and others have reduced their supply of food. Pigs can dig up several nests at a time, ants and rats destroy their eggs and eat the hatchlings, and goats, donkeys, pigs and cattle compete for the vegetation that makes up the tortoise’s primary diet. However, the tortoises are recovering in the wild due in part to intensive breeding efforts…in the 1970s, their populations had dropped as low as 3000 across the islands.
Unique to the Galapagos Islands, this is the only lizard in the world that can live and hunt in the sea. It can be found on all of the islands in the Galapagos (with the highest populations around Fernandina), generally preferring the rocky shorelines. Their dark, black or grey color enables them to warm quickly after a long dive, dives which can be up to 15 meters deep and last for a half an hour. They feed almost exclusively on marine algae. During breeding season, the males can acquire reddish or greenish coloration.
Galapagos Land Iguana
Another species of lizard endemic to the Galapagos, two species of these dinosaur like creatures live on the islands. One species has yellow to dark brown or black coloration, and is found in the drier areas of South Plaza, Santa Cruz, Isabela, Seymour, and Baltra islands. The other is found only on Santa Fe, and is primarily yellow in color with pronounced spines on its back. The land iguana can reach one meter in length, can weigh up to 13 kg (29 lbs), and can live for 60 years. Darwin described these creatures as “ugly animals… from their low facial angle they have a singularly stupid appearance”; yet the iguanas he encountered on Santiago Island are now extinct, also due to human activity and invasive species.
Seven species of lava lizards also live on the islands.
Sometimes called Darwin’s finches, these birds played an important role in the development of Darwin’s theory of evolution by natural selection. About 14 closely related species exist on the islands, all about the same size (similar to a sparrow) but differing in the size and shape of their beaks, reflecting an adaptation to different food sources. Their behavior differs as well, and they have different song melodies.
Endemic to the Galapagos Islands, these birds are identified by their streaked brown and grey feathers, long tail, slim shape and black beak. This was the first bird species that Darwin noticed differed from island to island. Their color enables them to blend well with the coral sands of the islands where they live. Unlike other mockingbirds, they are not mimics. Omnivorous, they will quickly devour any food left outside by humans.
Without natural predators and famous for its fearlessness toward humans, this bird has inhabited the islands for about 300,000 years. In size, it is similar to the Red Tailed Hawk of North America, with a wingspan of about 120 cm. An endangered species, it is estimated that there are only about 150 mating pairs of these birds left on the islands. Because of human disturbance of their habitat, competition for food by other introduced predator species, and hunting by humans, they are now extinct on Baltra, Daphne, Floreana, San Cristobal, and Seymor islands.
Two species of frigatebirds live on the Galapagos Islands. Their most distinctive feature is the bright red gular sac (below the mouth), prominent during courtship. These birds are known for their habit of stealing food from other species, but this does not make up their entire diet. They are unable to take off from water (or other flat surfaces), thus they catch fish, baby turtles and other prey from the ocean surface using their long, hooked bills. These birds spend most of their time in flight, able to spend about a week in the air, only landing to roost or breed on trees or cliffs.
These beautiful birds live in the salt water lagoons hidden within the islands. They have developed a filtration system in their beaks enabling them to filter fish and other food from the mixture of water and mud where they feed.
Other Species of the Galapagos
Apart from the numerous endemic species of the Galapagos Islands, there is an amazing variety of other life to observe, particularly marine life. The famous blue footed boobies nest on several of the Galapagos islands, and the red footed booby and the Nazca booby (among many other bird species) can be seen together on Genovesa. The Albatross is present on Española (the only breeding ground for these birds) from about April through December. Snorkeling anywhere in the Galapagos is an amazing experience, with sea lions, sharks, rays, beautiful and colorful fish, penguins, sea turtles, and much more…far too many species to mention here. Blue whales, humpback whales, and killer whales can occasionally be seen in the waters around the Galapagos Islands. Sperm whales are making a slow recovery from the hunting of the 19th century whalers. More commonly seen by tourists are schools of dolphins, which frequently follow in the waves of the tourist boats (three different species of dolphin live in the waters of the Galapagos). There is much more to see than we can mention here…a visit to the Galapagos is an experience not to be missed.