Saturday, April 28, 2018

Natural History: Iguana iguana


During a hike in Costa Rica, a mature male Green Iguana (Iguana iguana) was spotted basking next to a waterfall during the early afternoon on a hot, sunny summer day. This particular iguana was much habituated to human visitors making him very easy to photograph.  The specimen was approximately 3-3 ½ feet long from snout to tail, indicating that he was mature and between 3-5 years old. To identify the sex of this individual, the sexual dimorphism of the lower jaw in males are large, swollen looking “jowls” below the ear giving the head a large, blocky shape. Another indicator is longer spikes along the back of male green iguana. Although difficult to depict from the image, this male showed turquoise coloration along his head and neck with iridescent red colorations between his eyes; common among many iguanas of this species. With regards to thermoregulation, this individual was perpendicular to the sun maximizing surface area receiving sunlight. However, the cool breeze next to a waterfall helped maintain an equilibrium favorable for his thermoregulation. It is no surprise that this basking area is his known to be his favorite. Guides explained that this iguana is common to the area and it was extremely common for him to be spotted there. It wasn’t until 15-20 minutes into swimming around the rocks that this 3 foot iguana was even spotted! It was exciting to see a reptile this large remain so calm around a large group of humans.

3 comments:

Allison Welch said...

Great information! What an experience!

Anonymous said...

Nick- your comment on how it took a little while to spot this guy combined with his general appearance makes me consider the evolutionary adaptation of his cryptic coloration. He is able to blend in with the rock in order to protect himself from potential threats like predators. Upon doing some further research I discovered this animals common name is the green iguana- yet this one is not green. Don't worry however I think you are correct this is the right iguana and they can actually vary in color- especially as they get older they become less colorful typically. It is also interesting that this iguana appears quite light in coloration, but I believe you are correct in assuming it is trying to cool itself down as a lighter surface will reflect more solar radiation compared to a darker surface. It is know that if you take one of these iguanas into the sun it will usually darken because it is trying to absorb more heat. Additionally these animals may change color in mating season and develop orange coloration in males- quite interesting!

Anonymous said...

Nick, this is so cool! I would have loved to see an iguana up close in its natural habitat! I agree with Corey, having that tan and interesting coloration really helps this guy blend into the rocks! I wonder what types of behavior he would display if he felt threatened, and also how his appearance would change? It seems that he is quite used to people being around him as he does not look threatened in the picture. I wonder what their relationship with humans is like, generally? It seems that he finds us humans amusing too! Also, the way he is positioned in the picture against the rock suggests that he is maximizing his heat exposure, and he seems to be enjoying soaking up some sun. Great post!