FLORA AND FAUNA OF THE GALAPAGOS ISLANDS: MAIN SPECIES - BIOLOGY

The flora and fauna of the Galapagos Islands acquired worldwide recognition from Charles Darwin's work The Origin of Species (1858), because the nature of these islands played an important role in the development of this relevant scientific theory.

The Galapagos Islands are also known as the Colón Archipelago or the Galapagos Archipelago and are located 1,000 km off the coast of Ecuador in the eastern Pacific Ocean. It is an archipelago of 22 islands and more than 100 islets and rocks of volcanic origin, located on the equator, with great biodiversity.

Galapagos Islands. Source: NASA / Public domain

The whole of the Galapagos Islands is home to about 560 native species of angiosperm plants and 500 species of mosses, lichens and liverworts. While in fauna it brings together more than 7,000 species of all the large taxonomic groups, highlighting the species of turtles (10), birds and marine fauna.

Flora of the Galapagos Islands

Scalesia

It is a genus of shrubs and trees from the family of composites endemic (exclusive) of the Galapagos Islands. The species that reaches the largest size is Scalesia pedunculata, a tree up to 20 m tall.

These plants form dense forests or thickets made up of a single species and are part of the forests found on these islands.

Manzanillo (Hippomane mancinella)

Manzanillo (Hippomane mancinella). Source: (Dick Culbert from Gibsons, BC, Canada / CC BY (https://creativecommons.org/licenses/by/2.0)

This small tree is also called the "tree of death", because the resin it exudes is extremely toxic, so it is not advisable to stay in its shade. It is a tree with a greyish-brown twisted trunk and dense glossy green foliage with cream-colored ribs.

Palo santo (Bursera graveolens subsp. Malaccense)

This tree forms sparse forests on some islands, reaching 4 to 10 m tall, with its silvery-white spotted trunks. An essential oil used in traditional medicine is extracted from its trunk, in the same way its leaves are also used and it is an endemic subspecies of the Galapagos Islands.

Galapagos flax or Floreana flax (Linum cratericola)

This sister plant of textile flax is endemic to a crater on Floreana Island, with only 50 specimens in danger of extinction. These are small subshrubs with small narrow leaves.

Salt Mountain (Cryptocarpus pyriformis)

It is a shrub of the Nictaginaceae family with prostrate and creeping branches, with small white flowers, that forms low coastal thickets. It grows in the sand of the beaches, resisting well the salinity and the wind.

Darwin's cotton (Gossypium darwinii)

Darwin's cotton (Gossypium darwinii). Source: Benjamint444 / GFDL 1.2 (http://www.gnu.org/licenses/old-licenses/fdl-1.2.html)

It is an endemic species of these islands that reaches about 3 m in height, sister to commercially grown cotton. It has large yellow flowers and its fruit is a capsule that opens when ripe and reveals large specks of cotton.

Mangroves

In these islands there are four species of mangroves, the red (Rhizophora mangle), the black (Avicennia germinans), the white (Laguncularia racemosa) and the button (Conocarpus erectus).

These trees are characterized by being plants resistant to salinity, in order to be able to live in close contact with sea water and in the case of the red mangrove, their roots are submerged directly into the sea.

Galapagos Tomatoes

Two species of wild tomatoes are found in the Galapagos, Solanum galapagense and Solanum cheesmaniae. Being herbs with prostrate or creeping stems, with yellowish green leaves and golden-orange fruits when ripe.

Guayabillo or Guaba (Psidium galapageium)

This myrtacea is a tree up to 8 m tall with a trunk of smooth, grayish-pink bark and white flowers. It is an endemic plant of the Galapagos Islands, which has been introduced in other parts of America, since its fruits are edible.

Morning glory or morning glory (Merremia aegyptia)

It is a fickle climbing plant (its stem curls into logs, fences) of the Convolvulaceae family. It is a plant with thin hairy stems, palmate compound leaves and large white flowers that open at dawn, being introduced in the Galapagos.

Cactus of the genus

In the archipelago there are 14 species of these cacti with green and flattened stems armed with numerous thorns. The largest is Opuntia echios, up to 12 m tall and with a stem diameter of more than one meter (Opuntia echios var. Barringtonensis).

Candelabra cactus (Jasminocereus thouarsii)

It is a columnar cactus endemic to these islands, being a plant that grows up to 5 meters high. It is candelabra-like, with a light brown main stem and green upper stems with prickly ribs, large yellow flowers, and red berries.

Lava cactus or lava castle (Brachycereus nesioticus)

It is a species of cacti endemic to Bartolomé Island and adapted to the rocky substrates of lava that abound there. The species is about 60 cm with multiple cylindrical stems that are light green towards the base and yellowish towards the apex, and in mature plants the stems are dark gray with an orange upper part.

Miconias (Miconia robinsoniana)

Species of the genus Miconia (melastomatáceas) are abundant in the Galapago Islands, one being this shrub from 2 to 5 m from highlands. It has reddish stems, with green and reddish leaves, purple flowers clustered in dense inflorescences and giving rise to bright purple fruits.

Darwin's Lecocarpus (Lecocarpus darwinii)

It is a shrub belonging to the Compositae family whose genus is endemic to these islands. It has large leaves with serrated margins and yellow chapters (inflorescences with crowded flowers).

Passionflower (Passiflora foetida var. Galapagensis)

Passionflower (Passiflora foetida var. Galapagensis). Source: Jason Hollinger / CC BY (https://creativecommons.org/licenses/by/2.0)

It is a variety of the passion fruit or passion flower endemic to the Galapagos Islands. This climbing plant reaches up to 5 meters in height, its flowers are white and its yellow fruits are edible.

Darwin's Daisy (Darwiniothamnus tenuifolius)

It is an endemic species belonging to the compound family, with a highly branched shrub habit that grows up to 3 meters in height. It has chapters with white ligules (“petals”) and a yellow center, and its leaves are narrow and elongated.

Galapagos Islands fauna

Land tortoises (genus Chelonoidis)

Land tortoises are called galapagos in Ecuador, and precisely the great diversity of tortoises that exists gives the archipelago its name. In Darwin's time there were 14 species of giant tortoises, of which four have now disappeared.

The most famous individual of the last extinct species was Lone George, a male of the species Chelonoidis abingdonii. These giant tortoises reach more than one meter in length and more than 200 kg in weight.

Sea turtles

Leatherback turtle (Dermochelys coriacea). Source: US Fish and Wildlife Service Southeast Region / Public domain

At least five species of sea turtles are found in this region, including the mask turtle (Caretta caretta) and the leatherback turtle (Dermochelys coriacea). The olive ridley (Lepidochelys olivacea) and the hawksbill turtle (Eretmochelys imbricata) are also found in critical danger, while the other three are vulnerable.

Iguanas

There are five species of iguanas on the different islands, among which there is a marine iguana (Amblyrhynchus cristatus). The rest are terrestrial, such as the pink iguana (Conolophus marthae), the Santa Fe iguana (Conolophus pallidus) and the Galapagos land iguana (Conolophus subcristatus).

There is also the common iguana or green iguana (Iguana iguana) and a yet unidentified species of the genus Conolophus on the island of Santiago.

Lava lizards

Nine species of endemic lava lizards are found in this archipelago, all of the genus Microlophus. These lizards have skin tones according to the terrain where they live, being dark those that live on black lava rocks and lighter tones those of sandstone rocks.

Finches

Little Darwin's finch (Camarhynchus parvulus). Source: Mike Comber / CC BY-SA (https://creativecommons.org/licenses/by-sa/2.0)

This group of endemic birds of the Galapagos constitute the classic example of adaptive radiation linked to Darwin's evolutionary theory. These birds have adapted to the different islands in very different ways, forming up to 17 different species.

They belong to 4 different genera, which are Camarhynchus, Certhidea, Geospiza and Platyspiza.

Frigate bird

Of the genus Fregata there are three species, among which is the royal frigate of the Galapagos (Fregata magnificens magnificens). This species feeds on squid, crustaceans, fish remains, and young of other birds and iguanas.

They are birds that exceed 100 cm in length and 2 m in wingspan and the males have a red fur sac on the neck that they display when inflated (gular bag). The function of this sac is to attract females for mating.

Albatross

There are the royal albatross (Diomedea epomophora) and the wandering or traveling albatross (Diomedea exulans), these species can reach up to 3.5 m in wingspan. They are fishing birds that dive to capture their prey.

Boobies

There are 5 species of these birds in the Galapagos, all of the genus Sula, the most striking being the blue-footed booby (Sula nebouxii excisa). These birds have webbed feet of a very striking intense blue and feed on fish.

There is also a red-footed booby (Sula sula) and the Nazca booby (Sula granti) that has gray-green legs. Additionally there are the brown booby (Sula leucogaster) and the Peruvian booby (Sula variegata).

Galapagos Penguin (Spheniscus mendiculus)

It is the only penguin that lives in a tropical region and is listed as an endangered species. This penguin is able to survive in these tropical conditions, thanks to the fact that the waters of the Galapagos Islands are cold due to the influence of the Humboldt current from Antarctica.

It is a small animal, about 50 cm high and weighs about 2.5 kg, with a dark gray back and head almost black. It has white lines from above the eyes to the back and then down to the neck, the belly is white and the legs are gray.

Bats

Two species of bats are found on these islands, the Galapagos red bat (Lasiurus borealis brachyotis) and the large frosty bat (Lasiurus villosissimus). These are insectivorous animals, of course nocturnal.

Endemic rats

There are around six species of rats in the archipelago, including two introduced species, the Norwegian rat (Rattus norvegicus) and the black rat (Rattus rattus). The others are endemic to these islands, among them the fernandina rat (Nesoryzomys narboroughi) and the Galapagos rat (Aegialomys galapagoensis).

Sea lions or lions

Two-haired sea lion (Arctocephalus galapagoensis). Source: D. Gordon E. Robertson / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

Three species of sea lions live in the waters and coasts of the Galapagos Islands, one is the two-haired sea lion (Arctocephalus galapagoensis). The other two species are the South American sea lion (Otaria flavescens) and the fur seal (Zalophus wollebaeki).

These animals dive to great depths in search of the fish and mollusks that make up their diet. Adult males of the South American sea lion or wolf resemble a lion due to a coat of reddish or yellowish fur on their neck.

Dolphins

These aquatic mammals abound on the Galapagos Islands, where there are 8 species, belonging to six different genera. Among them are the common dolphin (Delphinus delphis), the Risso's dolphin (Grampus griseus) and the spinner dolphin (Stenella longirostris).

The latter is a small dolphin with a long snout, known for its acrobatic jumps in which it rotates on its own axis.

Sharks

There are about 15 species of sharks in the Galapagos Islands, distributed in 9 different genera. From the huge whale shark (Rhincodon typus) to the cat shark (Bythaelurus giddingsi) barely a foot in length.

The whale shark is considered the largest fish in the world reaching up to 12 m in length that has a dark gray skin with many white or yellowish spots.

There is also the peculiar hammerhead shark (Sphyrna lewini) and the potentially aggressive whitetip shark (Carcharhinus albimarginatus). There is also the tiger shark (Galeocerdo cuvier) with its blue to bluish green color with soft black stripes.

Bony fish

There are more than 500 species of fish in the Galapagos Islands, some of which are large, such as the black marlin (Istiompax indica) which is almost 5 m long. Others are small, such as Scorpaenodes xyris with its poisonous glands, which reaches about 15 cm.

References

Bensted-Smith, R. (ed.). (2002). A Biodiversity Vision for the Galapagos Islands. Charles Darwin Foundation and WWF, Puerto Ayora.
Charles Darwin Foundation. List of Galapagos species. (Viewed April 25, 2020). Taken from: darwinfoundation.org
Jiménez-Uzcátegui, G., Milstead, B., Márquez, C., Zabala, J., Buitrón, P., Llerena, A., Salazar, S. and Fess, B. (2007). Galapagos vertebrates: endangered status and conservation actions. Galapagos Report 2006-2007.
Johnson, MP and Raven, PH (1973). Species Number and Endemism: The Galapagos Archipelago Revisited. Science.
Ministry of the Environment of Ecuador (2010). Fourth national report for the Convention on Biological Diversity. Quito.
Wiggins, IL and Porter, DM (1971). Flora of the Galapagos Islands. Stanford University Press, Stanford.

FLORA AND FAUNA OF THE GALAPAGOS ISLANDS: MAIN SPECIES - BIOLOGY - 2025