Galapagos marine iguana - iguana lizards - island wildlife tours and islands cruises reptile life seen by passenger tour - cruise boats

They may look evil, vicious, even like something you would never want near your children, but Marine Iguanas are remarkably indifferent to your presence, very vegetarian, and you might even consider them for a quiet, hypo-alergenic family pet (if they were not a unique species in a protected environment). These lizards, which most likely share ancestors with their larger land dwelling cousins, have avoided the pressures of eating the limited vegetable resources on the islands. They have adapted themselves to gnaw algae off of the lava rocks close to shore. In order to digest their meal, they spend most of their days basking on rocks -- "cooking" their food after they have eaten it.

Perhaps no member of the Galapagos fauna has met with as much revulsion by historic visitors as the marine iguana, Amblyrhynchus cristatus. In 1798, Captain James Colnett wrote:

"The guanas are small, and of a sooty black, which, if possible, heightens their native ugliness. Indeed, so disgusting is their appearance, that no one on board could be prevailed on, to take them as food."

Captain James Colnett, 1798

Indeed, even Darwin himself was much replused by it, calling it "a hideous-looking creature, of a dirty black colour, stupid, and sluggish in its movements." In his diary, he noted that :

 "The black Lava rocks on the beach are frequented by large (2-3 ft) most disgusting clumsy Lizards. They are as black as the porous rocks over which they crawl & seek their prey from the Sea. Somebody calls them 'imps of darkness'. They assuredly well become the land they inhabit."

Charles Darwin, 1845

Marine iguanas are widely distributed throughout the islands. Although the different populations vary in size and color, they are all considered to be a single species. The smallest are found on Genovesa, and some of the largest are on Fernandina (above) and Isabela. The Isabela iguana below is the largest I have ever seen. Espanola boasts the most differentiated, colorful iguanas. These iguanas have blotches of coppery green and red. The red pigment comes from a particular seaweed that blooms during the summer months, which also coincides with the iguanas' mating season.

Marine iguanas are vegetarians, feeding primarily on sea weed in the intertidal zone. The biggest individuals, typically males, however, will swim out past the breakers and feed underwater. Their dives are typically shallow, 1.5 - 5 m, but large adults dive to depths of 15 m or more. Dive times are usually only a few minutes long, but there are records of iguanas being submerged for more than half an hour. Darwin described how a sailor tied a rock to an iguana on a line and threw it into the water. When he pulled it out an hour later, the iguana was still alive.