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Iguana Spikes Function

Describing The Purpose Behind Iguana Spikes

Iguana Spikes - What Is Their Function

I read this question on a website recently and it appears there was no real answer to it. Well, that is just not good enough for me, so I went searching and asking folks for their opinions. They are indeed just opinions, because as one responder pointed out, some questions you just can not really answer.

The answers fell into one of these 6 categories (in no particular order of importance).

Green Iguana (Iguana iguana)

Thermo-regulatory Function

Similar to the function of the dewlap, the spikes contain tiny blood vessels and actually have a blood flow. Circulating blood so close to the surface of the skin enables the spikes to cool the blood and therefore cool the body if necessary. So, it is reasonable to assume that they can and do act as an effective radiator, collecting and disseminating heat like a biological solar panel.

Aesthetics And Display Functions

Just like an extended dewlap or lateral compression, when the Iguana chooses to make itself appear larger, the spikes are stood upright. This gives the appearance of a much larger Iguana outline in an attempt to intimidate a rival or predator.

Camouflage Function

The spikes may very well act as a device to break up the Iguanas outline while in the trees (being some Iguanas are arboreal by nature), therefore helping to camouflage the Iguana from predators.

Mating Function

The spikes could be part of the mating display function. An Iguana engaged in a mating dance will upright the spikes creating a bigger, more dominant look to impress the females, and drive away rival males.

Defensive Function

The spikes could be part of a defense system which, while creating a larger outline fool the predator into thinking it has something to hold onto, when in fact a bite to the spikes would allow the Iguana time to escape with minor injuries. Also, the very sight of the spikes may help the Iguana fool the predator into thinking they will be injured if they try to attack the sharp, pointy creature (a porcupine effect, if you will).

Just Because Factor

Last, but certainly no less important. Maybe the spikes are there because our Creator wanted them to be. As pointed out to me on many occasions, some questions simply have no answers.

This represents an amalgamation of all the responses I received during my search for an answer. Some are more scientifically and evolutionarily based than others. In fact, no one knows for sure what the primary function of the spikes are. Most agree that the reason falls within one of the categories above.

Also, important to note, many in the Iguanidae family have no spikes or dewlaps. So, perhaps the species we are so familiar with Iguana iguana, developed this trait to help them cope with their particular place on the planet.

Either way, the question is interesting and has caused some folks to think about and re-examine the role of the spikes in this species.


Author: Dominick Giorgianni
Iguana Head © Bjorn Christian Torrissen [CC-BY-SA-3.0]