Herp Happenings! is a blog series dedicated to sharing the curious and wonderful things we all should know about amphibians and reptiles.
Why so cold blooded?
When first learning about herps (amphibians and reptiles), one of the first distinguishing traits taught is that they are ectothermic or cold blooded. But what does this actually mean and how does it affect the lifestyle and behaviors these animals possess? It is worth mentioning that these critters do not actually live their lives with icy blood running through their bodies but instead are able to tolerate much lower body temperatures that would otherwise cause problems for warm blooded endotherms like humans. Being ectothermic, herps must acquire the heat needed by their metabolisms from the environment and so, have developed traits and behaviors aimed to exploit this resource.
Where's the heat?

As the sun ascends into the sky each morning, the heat it exudes is absorbed by various objects in an animal’s environment and the rate at which the surface of these objects heat up is influenced by what they’re made of. While stones may become the hottest objects later in the afternoon, it may be surprising to learn that the surfaces of organic materials like wood will warm up sooner than stone, thus herps that begin their activity earlier in the day are likely to be seen basking on wood rather than rocks.
While absorbing heat through contact with warm objects is a great way for ectotherms to indirectly acquire energy from the sun, many reptiles have adapted an interesting ability that actually allows them to adjust the way in which they are able to absorb this heat directly. Some reptiles have the fascinating ability to adjust the melanin content within their skin; the same pigment that gives humans their dark hair, skin and eyes. By making themselves darker, reptiles are able to increase their absorptive ability thereby attaining heat more efficiently. That means you could see a dark lizard in the morning and a lighter lizard in the afternoon and it could easily be the same individual!
While absorbing heat through contact with warm objects is a great way for ectotherms to indirectly acquire energy from the sun, many reptiles have adapted an interesting ability that actually allows them to adjust the way in which they are able to absorb this heat directly. Some reptiles have the fascinating ability to adjust the melanin content within their skin; the same pigment that gives humans their dark hair, skin and eyes. By making themselves darker, reptiles are able to increase their absorptive ability thereby attaining heat more efficiently. That means you could see a dark lizard in the morning and a lighter lizard in the afternoon and it could easily be the same individual!
Perks of a cold heart
While ectothermy may have been an earlier developed trajectory in the tree of life, it is in no way primitive and provides unique benefits that are denied to the warm blooded kin. Being endotherms, human metabolisms demand a high caloric intake in order to maintain their constant body temperatures. Because ectotherms are excused from this demand, not only are they able to survive on less food –thus able to better survive in environments with scarce resources- but they are also able to invest a greater percentage of consumed energy into producing the next generation. |
Tips for siting Herps in the field!
- Touch test: Next time your exploring the outdoors looking for Herps, place your hand on different objects to check their temperature. If they’re too cold, odds are you won’t find anything basking on similar material down the trail.
- Search at a distance. Most reptiles have adapted excellent eye site that not only aids them in spotting food but also in avoiding approaching predators. Try looking 5-7 meters (15-20 feet) ahead when searching for critters in the wild. If you search too close, odds are they’ve already scurried away before you’ve had a chance to see them!
- Be patient. Stop and look for a little while, reptiles have adapted incredibly cryptic colorations and patterns and it’s likely you have walked right past some that were hiding in plain sight.
Herp Happenings! blog content provided by Tidal Influence Wetlands Restoration Intern - Daniel North