Mexican Spiny-tailed Iguanas

Local iguana at the marina

Iguanas are EVERYWHERE in Isla Mujeres.  The type of iguana found in Mexico is the Mexican Spiny-tailed Iguana, also known as the Black Iguana.  I had some previous experience with iguanas when we were scuba diving in Bonaire and found them to be quite aggressive.  As in...... I threw one or two of them part of a ham sandwich I was eating and QUICKLY discovered that a hundred of their "friends" suddenly appeared out of nowhere and decided to join them.  A big fight ensued over the sandwich with iguanas flying everywhere!  Then, they came toward LA and me sitting on the rocks and wanted more sandwich and got quite aggressive with us... as in, trying to climb up my leg!  We finally had to get up and move away from the area to get rid of them.  I learned NOT to feed the local wildlife that day!

So, naturally, I have not fed any of the Mexican iguanas as I do not wish to find out whether they like ham sandwiches as well.  Actually, iguanas only eat meat when they are young and still growing.  When they reach adulthood, they are almost strictly vegetarian and eat leaves, fruits and flowers. They are however, opportunistic and will also eat crabs, birds, small rodents and eggs.   They rarely have to drink in the wild as they get their water from the succulent plants that they eat.  From what I have seen here, the iguanas like to lay around and bask in the sun.....they are hard to photograph as they are very wary.  As soon as they are approached, they quickly run and hide under burrows in the sidewalks, under concrete, and in holes found in the side of concrete walls.  Most of the photographs here were taken right here at the marina.  The little iguanas are quite active and they run around all over the ground and climb trees.  At night the juveniles climb the lower branches of trees to avoid predators (snakes, hawks and raccoons...thankfully NONE of which I have seen!).  


Here are some facts I have learned about iguanas. (William and Joshua (our young nephews), take notice!)


All iguanas have strong jaws, long tails and strong legs with long, sharp claws, and the iguana family includes about 30 different species.

Mexican spiny-tailed iguana - Ctenosaura similis
There are 13 species belonging to the genus Ctenosaura. The Mexican Spiny-tailed Iguana, also known as the Black iguana, is one of the largest and most conspicuous lizards in Central America, ranging from southern Mexico to Panama. Through human introduction they can now also be found in southern Texas and Florida.

Hatchlings are a brilliant green color and are often confused with juvenile green iguanas, which look very similar. After about a year their color fades into the adult gray. The distinguishing features of the Mexican spiny tail are its tall dorsal crest and large rough spiny scales on its tail.

C. similis has been reported to produce 5 to 8 clutches annually, consisting of 12-88 eggs each. After a three month incubation period the hatchlings emerge. A small percentage will live through the first year and an even smaller percentage will live to adult hood. 

Most species of Ctenosaura are in peril. Contributing factors include habitat destruction and hunting for food and sport. The Spiny-tailed iguana is collected for the pet trade by the hundreds, compounding population declines. The animals that have found their way to Texas and Florida have adapted to their new environment and proliferate well. Unfortunately, as a non-native, invasive species they are considered a pest.


Great defense
Iguana tails are very hard and long. They use it as a whip to defend themselves. Iguanas, like most lizards, can drop their tails as a defense tactic to escape from predators. The skin, muscles, blood supply, nerves and bone can break at any point along the tail. Therefore, if a predator captures the tail, the iguana can run away leaving the tail still wiggling in the attacker’s mouth. The tail will eventually grow back, but it will not grow quite as long or be the same color as the old tail.
This iguana, lying along a wall, is huge.  He is about 3 feet long, nose to tail.



What is that under the chin?
If you look under the chin of most iguanas you will see a large loose flap of skin. This is called the Dewlap. The Dewlap can be moved in or out. The iguana sticks out its dewlap if it wants to show off or warn attackers. The dewlap also has many blood vessels running through the shallow skin. If it is a hot day, the iguana can stick out its dewlap to let heat escape. If it is a cold day, then the iguana can stand in the sun and stick out its dewlap to absorb as much sun rays as possible to warm up it’s body


Eye see the light!
Most animals have 2 eyes, but an iguana actually has 3 eyes! Their third eye is called the Parietal eye and it is found on the top of the iguana’s head. This eye does not see detail and color like our eyes, but it does see light (photoreceptor). The iguana uses this eye to recognize if it is sitting in sunlight or in the shade. This eye can also detect movement from above, so it could be vital in the early warning that a predator is over head!

Don't forget to blow your nose
The plants that iguanas eat contain a lot of salt. The salts are stored in sacs in their noses and when these sacs get full, the iguanas "sneeze" them out. There are marine iguanas that live on islands in the Pacific, called the Galapagos Islands. Because these iguanas spend all day eating seaweed off the sea floor, they ingest a lot of salt. Therefore, these iguanas have very large nostrils to “sneeze” out lots of salt. This can look pretty funny when a large group of marine iguanas are sunbathing together constantly sneezing!

Now, wasn't that educational!  You actually don't go brain-dead while cruising.  You actually have an opportunity to learn a lot of new things every day and it's fun while you are learning.  Listen up, kids...learning doesn't have to be boring!                                                                                      Big Iguana gives me the stink eye!

The photos below were taken of some iguanas at the South Point of Isla Mujeres (Punta Sur):



"Do not throw stones at the iguanas!"  

For all you iguana novices out there... a piece of friendly advice.. I would be more worried about a sign that warns you NOT to feed the iguanas.  That flimsy little fence will do nothing to stop them if a ham sandwich comes their way! Plus, about 1000 of their friends will show up from the rocks below to assist in the coming melee!

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