Iguanas of the Land and Sea

Iguanas of the Land and Sea

The Land Iguanas of the Galapagos come in three different subspecies. These subspecies are separated by island, there are two yellow varieties and a recently discovered pink subspecies found only near Wolf volcano. Land Iguanas feed mainly on the cactus flowers and pads found all over the Galapagos. They use their feet to scrape off the largest spines from the plant. As cold blooded reptiles, they need to bask in the sun in the daytime and sleep in burrows at night to conserve body heat. The have been known to reach 50 or 60 years of age and some can grow to over a meter in length, depending on the island they are from. These animals have also formed a symbiotic relationship with Darwin’s finches. The finches will sit on the backs of the iguanas and pick the bugs off of them; providing the finches with a meal and the lizards with some relief.

Question for the class: What is the difference between a species and a subspecies?

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Marine Iguanas are the only sea-going lizard in the world! They can dive to a depth of almost 10 meters to reach their favorite food: algae. Their blunt noses are perfectly adapted for scraping algae from the rocks at low tide. The largest iguanas can stay underwater for 30 minutes, but must return to the surface to heat themselves back up and return their heart rate to normal. Another thing that makes these reptiles amazing is that due to all of the time spent in seawater they have developed a gland to filter out the salt. This gland cleans the blood and allows them to sneeze out all of the salt they have taken in, which builds up as a white residue on their heads. When these iguanas are short on food, they shrink in size! It is thought that they absorb bone to provide nutrients and become shorter for the time being. Marine iguanas only dig burrows for nests, so they conserve body heat at night by sleeping in a large group. These iguanas have a symbiotic relationship with lava lizards. The lava lizards will eat the dead skin from the marine iguanas’ backs to enrich their diet. It is speculated that marine iguanas diverged from land iguanas 10.5 million years ago, after their shared relative most likely arrived on a raft of vegetation.

Question: What conditions would endanger the marine iguana the most?