Giant Tortoises   ׀   Turtles   ׀   Iguanas   ׀   Caimans

 

Iguanas     are large lizards and make up the family of Iguanidae and belong to the Squamata order of reptiles, which also includes all other lizards and snakes. They occur mostly in tropical America but some are also found in Madagascar, Fiji and Tonga. On mainland Ecuador occurs the wide-spread Green Iguana, living in trees close to water bodies. In the Galapagos islands are found three endemic species. Two species of the larger Land Iguanas are found on several islands and one specie of the Marine Iguana is encountered on all islands. This smaller iguana is the only ocean going iguana known in the world. Both are descendants of the Green Iguana, which reached the islands on vegetation rafts in the past and radiated then into those distinct species.   Iguanas are large lizards (shown here Green Iguana, photo taken in Semario Park in Guayaquil) which have scales on the side and under their body, distinct moveable eyelids, external ear drums, throat pouches, also called dewlaps, a long detachable tail, 4 limbs with 5 toes with sharp claws and on the back they have a row of leathery spines. They can reach lengths of up to 1.8m.   It is believed that Green Iguanas reached the Galapagos islands in the past on vegetation floats from the Pacific coast. This iguana is common throughout tropical America and is arboreal, feeding mostly on vegetation, which is abundant on the tropical Pacific coast. On the much drier Galapagos islands with its sparse plants, they had to adapt however to be able to survive in this new and more hostile environment. So over thousands of years they radiated into basically two new species, land and  marine iguanas. The Land Iguanas started to consume the plants found on land, especially on the prickly pear cactus, which also provides a water source for it. The Marine Iguanas on the other hand found their food solution in the oceans, by consuming algae and other plants growing on the submerged rocks near the shores.   Marine Iguanas are very interesting as they are the only iguanas in the world which adapted themselves to a partial life in the oceans. They go to the sea primarily to feed on algae growing on the rocks. Lungs adapted themselves so that they are able to stay longer underwater and they propel themselves with their flattened tails. Going to sea has however risks involved as other predators like sharks await them there but that was a reasonable trade-off for the ample food supply. Most of the time is still spent on the black lava shores where they have to warm up after cooling in the cold water. This is probably the main reason why they are mostly black as that color absorbs most of the sunrays and lets them achieve faster proper body temperatures. Older iguanas have a white crest on the head which is actually excess salt expelled by themselves through spitting and which over time settles there. They are still numerous in numbers and not considered in danger of extinction.     Two species of Land Iguanas are recognized on the islands. The Galapagos Land Iguana (photo above taken on Isabela island) was once abundant on many islands but became extinct on some of them because of hunting and introduction of feral animals, which prey on their eggs or kill the recently hatched young. The Charles Darwin Station started therefore a breeding program for those iguanas and they were consequently re-introduced on some islands. The Santa Fe Iguana is as its name suggest only found on that island. Both are similar in looks with the Santa Fe species slightly larger and paler in its coloration. Both may weigh up to 6kg and reach one meter in length. They mostly feed on vegetation and their preferred meals are the fruits of the Prickly Pear Cactus. They are able to devour the whole fruit pads with spines intact. A very leathery mouth lets them achieve that. Land iguanas reach sexual maturity at between 6-10 years and may live to 60 years.   Iguanas show impressive courting and defensive displays by raising their bodies upwards, bobbing their heads vigorously and erecting their dorsal spines. Males sometimes keep various females which they defend with a small territory against other rivals. The females lay from 2- 25 eggs depending on the species, in underground holes, from where then the young hatch. At that time they are most vulnerable having some natural predators like the herons, hawks, snakes and wild dogs. Another predator is man as both their eggs and meat are highly valued food items. Hunting and deforestation leads locally to reductions in their numbers.   At breeding time the males of marine iguanas, especially on the southern islands (below right on Española) take on bright colors, especially red and green. The smaller and drabber females (below to left) dig holes and lay their eggs in those underground nests. Also that time iguanas become aggressive and defend their territory and harem against any rivals (see above head butting fight).

Ecuadorian  Species   Name Scientific Location   Green Iguana Iguana iguana Pacific Marine Iguana Amblyrhynchus cristatus Galapagos (endemic) Galapagos Land Iguana Conolophus subcristatus Fernandina, Isabela, Santa Cruz, Seymour & Plazas (endemic) Santa Fe Land Iguana Conolophus pallidus Santa Fe (endemic)        Reptile Vocabulary   Herbivorous:  reptiles feeding almost entirely on vegetation, e.g. iguanas. Carnivorous:  reptiles feeding on live-caught animals including insects, e.g. caiman. Omnivorous:  reptiles feeding on both plants and animals, e.g. aquatic turtles.