Although many species of flora and fauna that thrive on the Galapagos Islands resemble those native to South America, they have evolved so extensively in isolation that they now appear very different from their mainland ancestors. The plant life of Galapagos is just as extraordinary as its wildlife, although it receives less attention and publicity.
There are 560 native species of plants in the islands, in other words, plants which arrived in the islands by natural means. Of these, 180 are endemic to the islands, meaning they are found nowhere else on earth. For example, Galapagos has its very own, endemic species of cotton, pepper, guava, passion flower and tomato. Not only that but many species are so different from others elsewhere that they are grouped in their own endemic genera. These include Scalesia, the endemic ‘daisy tree’, which has evolved into a whole host of different species in a direct botanical parallel of the Darwin’s finches. Other endemic genera in the daisy family are Darwin’s aster Darwiniothamnus, the cut-leaf daisy Lecocarpus and needle-leaf daisy Macraea. There are also some endemic genera of cacti, Brachycereus, the lava cactus and Jasminocereus, the candelabra cactus.
Many endemic plants are rare and endangered, but on the whole, Galapagos plants tend to be ‘pioneer’ species, hardy plants which successfully cross oceans and manage to establish themselves in the often hostile environment of islands. Because relatively few plants succeed in doing this, the flora is ‘depauperate’ – there are far fewer species here than in similar environments on the South American mainland. Plants are also adapted to having very few insects or other animals to pollinate their flowers or disperse their fruits and seeds. This means there are few big, showy flowers to attract pollinators and few specialised fleshy fruits. But there are some fascinating relationships between plants and animals. The giant tortoises and land iguanas, for example, feed on Opuntia, the prickly pear cactus, and have influenced its growth form on different islands.
The island’s flora lives in specific zones. Understanding these zones helps with identification and appreciation of the flora. From the Mangrove Swamps that cover the wet coastal zone and the Prickly Pear Cactus of the Arid Lowlands to the Scalesia Trees and Miconia of the higher Humid Zones, the Galapagos hosts an interesting array of flora in a complex ecosystem.
Up TOPLife Zones
There are four universally recognized vegetation zones, which occur throughout the archipelago: Littoral, Dry, Transition, and Humid. Various plants and animals have adapted over the years to the conditions of the islands and, in some cases, the conditions of the zone. Flora is normally found in a specific zone and the fauna that is dependent on those plants can be found there as well. Some birds and animals migrate between zones depending on conditions.
This is the coastal fringe of the islands and includes beaches, mangroves and brackish lagoons. Predominant plants are the mangrove trees, and in drier areas bushes and grasses that tolerate salt. The four mangrove tree species that are commonly found in protected coves and lagoons are red (Rhizophora mangle), black (Avicennia germinans), white (Laguncularia racemosa), and button mangrove (Conocarpus erecta). Some of the smallest islets are entirely covered by Littoral Zone vegetation.
The Dry Zone is the most widely distributed zone, and many islands, even some of the larger ones such as Genovesa, have no other vegetation type except the coastal fringe. The Dry Zone rises higher on the north side of the higher islands, which is in the rain shadow of their peaks. It can often be subdivided into a lower scrub zone and an upper woodland zone. This region is home to many cacti such as prickly pear (Opuntia spp.), giant candelabra cactus (Jasminocereus thouarsii) and the pioneer that settles into hardened lava flows, the lava cactus (Brachycereus nesioticus).
Vegetation becomes denser as the altitude and rainfall increase. The Transition Zone includes species from both the lower Dry and the upper Humid Zones. There is a variety of small trees or shrubs, including the endemic Guayabillo, with a small white flower, and a small guava-like fruit, and the endemic Galapagos tomato that is salt tolerant.
Depending on the local rainfall, altitude and soil type, this zone may be further divided into sub-zones: the Scalesia forest (a zone dominated by a tree daisy), Miconia scrub and the Pampa zone (dominated by ferns and sedges at the highest altitudes). The humidity is highest in the humid zone, although much of the moisture comes from misty conditions rather than rain, and the vegetation is rich in bromeliads, ferns, orchids and mosses, many of them growing as epiphytes on tree branches.
Only the seven highest islands, such as Santa Cruz and Isabela, include all these zones.
The Islands have a wide array of endemic fauna, invertebrates, birds, reptiles and a few mammals native to the islands rather than introduced. The Galapagos Tortoise is the most well known of all the endemic creatures. These giant tortoises, all of which are endangered due to hunting and introduced species, include 11 subspecies adapted to the terrain of their island home.
Colorful and plentiful iguanas are a common endemic. The Galapagos is home to Land Iguanas, Marine Iguanas and a hybrid of the two. Long known as a haven for birders, the Galapagos Islands’ native bird life includes 57 residents almost half of which are endemic, the rest are migrants. Darwin’s Finches include 13 species that have adapted to their island setting. Other endemics include the Lava Gull, Galapagos Penguin, Dark-Rumped Petrel, Galapagos Flightless Cormorant, Lava Heron, Galapagos Martin and the Galapagos Dove.
Life in the ocean is as varied and unique as that above it. The Galapagos Marine Reserve is home to sharks, rays, fur seals, sea lions, whales, dolphins, starfish, marine iguanas, penguins and more. Green Turtles and Hawkbill Turtles can be seen in the waters. The Sally-Lightfoot Crab (bright red in color) can be seen along the shore.
Galapagos Birds and Animals
Early in the development of the islands, many migratory birds made their way across the seas from neighboring Colombia, Ecuador and Peru. Over the years, additional birds began to arrive with the assistance of the trade winds. Today, of the 19 species of birds residing in the Galapagos 50% are endemic and 25% are exclusive to the islands including the Galapagos Penguin, Flightless Cormorant, Waved Albatross, Lava Gull and the Swallow Tailed Gull. More than 700,000 migratory sea birds can be seen in the islands. The Galapagos is home to almost 1/3 of the worlds Blue Footed Booby population and has the highest concentration of Masked Boobies and the largest colony of Red Footed Boobies in the world.
While some birds have changed little over the years from their ancestors who first arrived in the islands, others have altered slightly to create a new sub-species in the Galapagos like the Vermillion Flycatcher and the Short Eared Owl . Others have developed into new species like the Galapagos Hawk and the Galapagos Dove . The most dramatic evolutionary changes can be seen in birds like the Mockingbirds or Finches, which have developed into several new sub-species depending on their environment in the islands.
With the lack of predatory mammals, life on the islands is dominated by reptiles. The most famous is, of course, the Galapagos Tortoise, along with land and marine iguanas, lava lizards and sea turtles . These creatures closely resemble their relatives on the South American continent. There are 27 species of reptiles in the Galapagos of which 17 are endemic.
Galapagos Marine Life
The combination of warm tropical waters and the upwelling of the nutrient rich, cool Humboldt waters allows the Galapagos Islands to support a wide array of marine life. More than 2,900 marine species have been reported and over 18% of those live nowhere else on earth. These waters are home to sharks, whales, penguins, sea lions, fur seals, sea turtles and 306 varieties of fish, 25% of which are endemic. There are few coral reefs in these waters, instead the crevasses in the lava function as a reef would in other environments. Smaller fish live protected within the crevasses, coming out to feed. Invertebrates make their home in the lava. The marine food chain is established around the lava as larger fish live near the lava area where they feed on the smaller fish. Smaller marine species that are at the base of the food web for many of these larger animals include sponges, corals, anemones, gorgonians, shrimps, conches, and starfish.
Sea Turtles: The Pacific Green Sea Turtles spend most of their lives in the ocean. Adult shells grow to 3 ft (1 m) in length with a body weight of up to 400 lbs. (180 kg). These cousins to the tortoise mate in the waters near the Galapagos and are often seen near Caleta Tortuga Negra on Santiago . Males never leave the sea, but females come ashore to lay eggs and nest on several of the islands. Green Sea Turtles are an endangered species. Turtle eggs are eaten and pigs and rats frequently destroyed their nests. Hawks, herons, mockingbirds, and frigatebirds prey on young hatchlings. If these young turtles make it to the sea, fish and sharks hunt them.
Whales & Dolphins: Fortunately, the days when The Galapagos Islands were the center of whaling in the Pacific Ocean are long gone. Many of these large mammals still visit the Galapagos during their migrations. The larger whales, including the Blue, the Finback, the Sei, the Humpback, the Bryde’s, the Minke, the Sperm Whale, the Orca, the False Killer Whale, and the Short Finned Pilot Whale can all be seen in the Galapagos waters. The Bottled Nosed Dolphin and White Bellied Dolphin also live in these waters. Bottled Nosed Dolphins can be seen riding the bow wave in front of boats. White Bellied Dolphin can be seen in schools of more than 100.
Viewing the Marine Life
Diving in the Galapagos offers exceptional opportunities to view pelagic life in the islands. Sea Lions, Hammerheads, Galapagos sharks, Whale Sharks, Eagle and Manta Rays and vast shoals of reef fishes can regularly be seen on diving day trips from around Santa Cruz island and the nearby central islands. Snorkeling excursions in places like Devil’s Crown, a submerged volcano, offers an experience similar to swimming in a tropical fish tank. Head to Academy Bay to swim with a colony of sea lions.