Natural History of the Galapagos Islands

Having arisen out of the Pacific ocean the newly formed islands were in the beginning devoid of any life. Hard and barren lava however transformed itself over time into smaller sand and soil particles through weathering processes and paved so the way for the establishment of life. The first animals other than the marine ones to take advantage of the new habitat were seabirds for fishing and nesting purposes. They also carried seeds in their guts or stuck to their bodies to the islands. Half of the plants now established on Galapagos thus arrived in that manner. Other plants got there also by wind dispersion (some 5%) or carried by ocean currents (some 7%). The rest were then introduced later by human settlers. Shorebirds followed and smaller land based birds got accidentally blown in by strong winds as did insects and one specie of bat. Many perished but by sheer luck some breeding populations (might have been only one pregnant female) could establish themselves there. The 13 species of Darwin finches descended thus from one common ancestor finch. They were able to speciate because of geographical isolation but also of ecological isolation by finding new niches and slowly developing new feeding and breeding habits. Land animals got to Galapagos by being stranded on vegetation rafts. Chunks of land which broke off on the continent were carried by rivers to the Pacific and then by ocean currents to the isles. Warm-blooded mammals have however difficulty to survive long rafting trips (only some mice arrived thus) whereas the chances of cold-blooded reptiles are much better as they can go much longer without food. For that reason initially there exited a disproportionate larger number of reptiles over mammals. Tortoises, lizards, snakes and iguanas had the insular region to themselves and by adapting transformed themselves into the present species. That changed then as human settlers introduced later their domestic animals. Some escaped or were left to themselves and became feral animals playing havoc on the native reptiles. That and other factors like hunting by humans and introduction of exotic plants brought some species to the brink of extinction.

 Identification Guide to Animals and Plants

Below you find an identification guide of animals and plants which are most easily observed on the islands. By clicking on the links you get to pages with photos and short descriptions of them. That should help you in getting to identify the unique living organisms of the isles.

FISH

Tropical Reef Fish I   

Tropical Reef Fish II

Sharks and Rays


ECHINODERMS

Sea Stars, Urchins & Sea Cucumbers


BIRDS (some 60 resident birds with half of them being endemic and some 25 migratory birds)

Birds along the Shore

Birds of the Sea

Birds on the Land


REPTILES (22 species, all of them endemic except three species)

Turtles, Snakes, Lizards and Iguanas


MOLLUSCS & CRUSTACEANS (rich representation of marine invertebrates)


INSECTS (some 1000 species make their home on the islands)


LAND MAMMALS (six native land mammals and introduced ones, gone wild)


SEA MAMMALS

Sealions  
Two species:  Galapagos Sealion and Fur Sealion

Whales and Dolphins:
Three species of dolphins: Bottled-nosed, Spinner and Common Dolphins.
Seven whale species: Humpback, Sperm, Finback, Minke, Sei, Killer and Pilot Whales.


PLANTS

Vascular non-flowers and non-vascular plants (some 650 species)

Flowering plants (some 750 species with 215 of them endemic, 270 natives and 265 exotic).

Flowers of the Coastal Zone

Flowers of the Arid Lowlands

Flowers of the Moist Uplands