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18/07/2017 Wildlife facts

Symbiotic relationships in Galapagos

Many of the Galapagos Archipelago's most iconic species rely on each other and form symbiotic relationships.

Photograph of Jenny Vidler

Jenny Vidler

Former Communications & Membership Assistant at Galapagos Conservation Trust

The natural world is full of creatures that rely on each other for survival, as well as an easier life. The food chain is the most basic example; without the single cell organisms at the bottom of the food chain, the apex predators could not exist and vice versa. Nowhere else are symbiotic relationships more evident than in Galapagos. Across the Archipelago, animals are spotted clinging on to one another to share heat, feeding on other species to gain a more varied diet and seen cleaning their neighbours from parasites.

Commensalism

The symbiotic relationship known as commensalism benefits the first participant, and causes no harm to the second participant. A good example of a communalistic relationship in Galapagos is between the Galapagos dove and the Opuntia cactus. The dove burrows into the cactus to nest and rest, using the plant as shelter. The cactus, however, is not affected positively nor negatively from the dove residing within its pads.

Galapagos Dove © Judi Miller

Mutualism

Mutualism is a description of a relationship between two animals found very commonly in the natural world. Mutualism is a relationship where both organisms benefit from each other, such as the Galapagos giant tortoise and the Galapagos finches as well as some mockingbirds. The bird flies in front of the tortoise to show that they are present. The tortoise then stretches out its neck and legs so that the bird can reach ticks and other parasites often found on the skin of the tortoise. This means that the Galapagos giant tortoise is relieved of parasites and the bird achieves an easy meal, with them both benefitting from the exchange.

Galapagos Moment © Jen Jones

Mutualism

Mutualism is a description of a relationship between two animals found very commonly in the natural world. Mutualism is a relationship where both organisms benefit from each other, such as the Galapagos giant tortoise and the Galapagos finches as well as some mockingbirds. The bird flies in front of the tortoise to show that they are present. The tortoise then stretches out its neck and legs so that the bird can reach ticks and other parasites often found on the skin of the tortoise. This means that the Galapagos giant tortoise is relieved of parasites and the bird achieves an easy meal, with them both benefitting from the exchange.

Giant Tortoise and bird © Mark Altman

Another common mutualistic sight in Galapagos is the relationship between sally lightfoot crabs and sea lions. The crabs are often seen creeping along the backs of the sleeping sea lions, eating ticks off the mammals while they lay on the white sand beaches. Lastly, lava lizards are frequently seen close to colonies of marine iguanas. Pesky flies are attracted to the masses of sunbathing reptiles, but as marine iguanas are herbivores, they rely on the much smaller lava lizards to remove the flies.

Parasitism

Ticks suck blood from the Galapagos giant tortoise while living on the reptile’s neck and leg skin. This is parasitism because only one organism is benefiting, the tick, while the other one is being harmed, in this case the Galapagos giant tortoise. A second example of parasitism is vampire finches feeding on the blood of Nazca boobies. The vampirefinch benefits as it supplements its diet using the bird’s blood, but the Nazca booby can be negatively affected. Although only a small amount of blood is taken by the finch, the wounds made on the booby’s body can become septic which can negatively affect the larger bird, especially if it is nursing young or eating less than usual.

Vampire Finch © Simon Pierce

Galapagos is often likened to a microcosm of the globe. In Galapagos, it is easy to see that many animals, including humans, are part of symbiotic relationships. Without tourism, Galapagos may not be the protected region it is today and without the wealth of animal life, Galapagos would not be the tourist destination it is today. When humans and wildlife are able to co-exist, it creates a positive relationship of mutualism which is imperative for the health of the Archipelago, and indeed the world.

If you would like to help protect the wildlife of Galapagos, please click here to donate to GCT.

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