Grab & Go

NAME: Land Iguana and Marine Iguana – both in the Family Iguanidae

CLASSIFICATION: Land: Ge- nus Conolophus; Species (two) subcristatus and pallidus Marine: Genus Amblyrhynchus; Species cristatus

MAIN MESSAGES: The Galapagos are a quintessential example of islands as living laboratories of evolution. ✤ Beginning with Darwin and Wallace, the study of islands has provided insight into how organisms colo- nize new environments and, through successive genera- tions, undergo changes that make their descendants more suited to thrive in the new environment CAS has made research ex- peditions to the Galapagos and has been involved in conservation efforts there for over 100 years. ✤ CAS collections from the Galapagos are the best in the world. Today, the Academy continues its research in the Galapagos and maintains the best collection of Galapagos materials in the world. Scientists at CAS collect plants and animals on research expedi- tions around the world. Their work and Academy collections provide invaluable baseline information about human impacts and change over time.

DISTRIBUTION AND HABITAT: All are inhabitants of the Galapagos Islands. A spiny- tailed Central American Iguana may be ancestral to all three, but the marine species evolved from the terrestrial iguanas and thus is endemic to the Galapagos. Further, it is the only sea-going iguana in the world, and spends its entire life in the intertidal/sub- tidal zones. Although the land iguanas live on several islands, they are mostly seen on Plaza Sur. More widespread, the marine iguanas are seen in the channel between Isa- bella and Fernandina and along the cliffs of Espanola.

DESCRIPTION AND DIET: Marine iguanas may range from 2 to 20 lbs, usually with a blackish color. Their faces are foreshortened, and they have a row of small flexible spikes along their backs. Similar in size, land iguanas have yellow heads with deeply ridged scales, more elongated faces, and a flap of skin hanging below the throat.

As reptiles, iguanas are cold-blooded, can go for long periods without food or water, and are mostly vegetarians. The marine iguanas live almost exclusively on nutrient-rich ma- rine algae. The land iguanas may graze on blossoms of Portulaca but they thrive on Opuntia cactus pads. Grab & Go

PREDATORS: For marine iguanas, dark coloration provides some camouflage against land predators, but they may be prey to Galapagos hawks. Young marine iguanas, however, are susceptible to herons, hawks, lava gulls, and feral cats. Land iguanas are prey to rodents and various mammals; and survival of baby iguanas is less than 10%.

REPRODUCTION: Male marine iguanas congregate in leks for territorial encounters, to posture, bob heads and whack skulls together in shoving matches. They must then en- tice reluctant females to mate, courting with slow, circles around them. The females lay egg clutches in shallow burrows. Land iguana behaviors are similar although somewhat more aggressive.

LIFE SPAN AND CONSERVATION: Land iguanas can live to 50–60 years and, al- though now threatened, are a focus of conservation at the Darwin Research Center. Marine iguanas are numerous.

INTERESTING FACTS: Marine iguanas have a salt excreting gland on their foreheads. In years of food shortage (e.g. during El Ninos), iguanas may actually shrink in size, up to 20%.

Darwin thought land iguanas looked “stupid” and he famously described marine iguanas as “hideous-looking creatures.”

WHERE IN THE ACADEMY? The Green Iguana is arboreal, and lives in the Anaconda exhibit on the Amazon Flooded Forest floor.