As difficult as it is to describe the outrageous animals in the Galapagos Islands, probably the most challenging ones to chronicle are the two (ok, now three) kinds of iguanas making their homes there. I love these guys!
Marine iguanas are gray-brown, tiny, dinosaur-like creatures who frolic in the sea and live on algae (except when breeding and they turn red & blue!) And the Galapagos’ land iguanas are these big headed, bright yellow fellows (and ladies) who feast on cacti and other plants while looking crazy beautiful against the stark, rocky Galapagos landscapes. Magnificent!
I say three types because a third species, very similar to the yellow land iguana, has recently been discovered near Wolf Volcano on Isabela Island, the pink iguana! These stylish residents turn rose with black stripes during mating season and they are localized to a fairly small territory. That isolation is one of the things that’s so fascinating about the Galapagos!
Both the marine iguana and the land iguana are only found in the Galapagos and they both evolved from a common ancestor. As centuries passed, marine iguanas took to the seas for nourishment and developed a chummy kind of culture where they sleep together and hang out together sunning on seaside rocks. Their land iguana cousins, however, stuck to the rocky hillsides and sparse shrubbery and evolved a completely different, more solitary lifestyle where they usually only come together to mate or defend their territory. How could animals who started out so similar become so different?
In 1835, during his voyage through the Galapagos on the HMS Beagle, Charles Darwin was certainly captivated by the beak differences of Galapagos finches from island to island and this study helped him develop his theory on natural selection. Yet it was the marked differences between marine iguanas and land iguanas that helped him solidify his theory on the principles of adaptation and speciation.
The distinct differences between land and marine iguanas, as well as their adaptations to completely different environments served as evidence for Darwin that species evolved in different directions in order to fit in and survive in whatever conditions they found themselves in.
The seafaring marine iguanas have developed these special behaviors:
Swimming and Diving: Marine iguanas are excellent swimmers and divers. They use their powerful tails to propel themselves through the water, and their flattened bodies help them move efficiently. They can dive to extreme depths in search of their primary food source, marine algae.
Basking: After spending time in the cold ocean, marine iguanas often bask in the sun on rocky shores to warm up. They spread their limbs to maximize exposure to sunlight and regulate their body temperature.
Salt Excretion: Unlike most reptiles, marine iguanas have specialized salt glands near their nostrils. These glands allow them to expel excess salt that they ingest while feeding on marine algae. This adaptation is crucial for dealing with the high salt content in their diet.
Group Nesting: Marine iguanas often nest in colonies. During the breeding season, females gather in groups to dig communal nests in the sandy soil. After laying their eggs, they cover the nest, and the communal nesting behavior can provide some level of protection against predators.
Sneezing: Marine iguanas have a unique way of expelling excess salt. After feeding in the ocean, they may expel salt through their nostrils, often referred to as "sneezing." This behavior helps them get rid of the salt they accumulate while feeding on marine algae.
LAND IGUANAS Their cousins, the land iguanas have developed these behaviors:
Cactus Pads, Fruits & Grasses: Unlike marine iguanas, land iguanas feed on the pads of prickly pear cacti, which are abundant in the arid zones of the Galápagos Islands. They adapted to eat the tough, spiny cactus pads, and the moisture content of the pads helps fulfill their hydration needs. They also consume fruits and flowers from various plant species, plus grasses and leaves, particularly from low-lying plants to add some variety to their diet .
Basking: Like many reptiles, land iguanas bask in the sun to regulate their body temperature. They can often be seen on rocks or open areas, soaking up the sunlight.
Burrowing: Land iguanas dig burrows to escape extreme temperatures or to find shelter. These burrows also serve as nesting sites for females.
Territorial Behavior: Unlike the chummy marine iguanas, land iguanas exhibit territorial behavior, especially during breeding season. They might defend certain areas or engage in dramatic displays to establish dominance.
Nesting: During breeding season, female land iguanas dig nests in the ground to lay their eggs. After laying the eggs, they cover the nests with soil.
Estivation: In times of extreme heat or drought, land iguanas enter a state of “estivation” or a state characterized by inactivity and a lowered metabolic rate. During estivation, they remain in burrows or seek shelter to conserve energy and reduce water loss.
Isn’t it amazing how two animals in virtually the same place and habitat took such different paths of evolution? And this is just one of the hundreds of stories you’ll here about exotic animals and their distinctive evolutionary paths when you travel to the Galapagos Islands.
And did I mention that they don't run away when they see you? They are very happy to stand still while you take their photo. This is true of all the animals in the Galapagos. They're just not afraid of humans!