February 2023’s Animal Of The Month – Green Anoles

By February 28, 2023 No Comments

February may be the shortest month of the year, but that doesn’t mean our Animal of the Month for February is short on being a fascinating creature. If you were following us on Twitter @ExoticPetVets, you would have seen how these little lizards are big on being able to adapt to their environment – which is not a good thing in areas where they are an invasive species. But if you missed any of our tweets, you can find a summary of them right here that you can use as a reference any time. Did you know?:

  • Green anoles (Anolis carolinensis) are small North American lizards endemic to the southeastern United States. Their natural range stretches from North Carolina south to Florida and west through to Texas.
  • But green anoles are also an invasive species, with introduced populations believed to be the result of escaped pets or pets being deliberately released into the wild.
  • Introduced green anole populations are found around the world, including southern California, Hawaii, the U.S. territory of Guam, Japan’s Ogasawara Islands and Okinawa Island, the Caribbean and Spain.
  • Local insect populations have been decimated in some areas with introduced green anole populations.
  • In Japan, green anoles are being blamed for the possible extinction of the blue Japanese butterfly (Celastrina ogasawaraensis) on the Ogasawara Islands. The last confirmed sighting of the butterfly was in 2018.
  • If the blue Japanese butterfly is confirmed extinct, the green anole would be held largely responsible for the first ever extinction of an endemic butterfly species in Japan.
  • Wild green anoles can be found in habitats with trees and high humidity; including forests, swamps and wooded beaches.
  • Green anoles are mostly arboreal reptiles, meaning that they spend much of their time in trees. But they can also be found in shrubs, on vines and in tall grass.
  • In populated areas, wild green anoles can be found hanging around on fence posts and on the sides of buildings as they bask in the sun.
  • It probably comes as no surprise that green anoles are green. But did you know that they can change their colour to various shades of brown and grey?
  • While commonly referred to as “chameleons” because of their ability to change colour, green anoles are actually not chameleons at all.
  • Green anoles can quickly change their colour if they are agitated or if they are cold and their environment is causing them stress.
  • Green anoles are able to change colour based on pigment cells in their skin. These cells are collectively called chromatophores.
  • Three types of chromatophores are present in a green anole’s skin – melanophores, cyanophores and xanthophores. Under white light, melanophores have a brown/black hue, cyanophores have a blue hue and xanthophores have a yellow hue.
  • This is a fascinating video taken of a green anole changing colours in a Texas garden. The video is two-minutes long in real time, but is compressed into a 30-second clip.
  • Green anoles are small, slender lizards. Fully grown they reach lengths of between 4 – 8 cms (1.5 – 3 inches) with more than half of that length made up of their long thin tails.
  • Green anoles have arrow-shaped heads with long snouts. Their dark eyes are on the sides of their heads and typically have a thin turquoise ring around them. They have white mouths and bellies, while the rest of their bodies are green.
  • Male and female green anoles are sexually dimorphic, meaning there are obvious visual physical differences between males and females.
  • Female green anoles are usually smaller than their male counterparts. Most females also have a dorsal line that starts at their necks, runs along their backs and ends where their tails begin.
  • Male green anoles typically have a dewlap, which is a fold of loose pink-coloured skin on the underside of their necks that they display to attract mates and during territory disputes with other males.
  • “Heavyweight” and “lightweight” are terms that are not only reserved for drinkers and for weight classes in human sporting events, but they also apply to male green anoles!
  • Male green anoles are classified as either heavyweights or lightweights depending on several factors; which include size, dominance, vertical jump and bite force.
  • The evolutionary process is often a slow one. But if you currently have an infant, the green anole can evolve faster than the time it takes for your child to grow up and graduate high school.
  • In 2014, researchers published a study in which they observed the green anole developing larger and stickier toe pads in the span of 20 generations, which is about 15 years.
  • What prompted the green anole to evolve was the introduction of Cuba’s brown anole in Florida. The brown and green anole are not only similar in size, but their diets and habitats are also similar.
  • Brown anoles are trunk-ground dwellers, so they are either on the ground or within 5-6 feet (1.5 – 1.8 m) off the ground – usually on tree trunks. Their presence forced green anoles higher up into the trees.
  • The green anoles developed their larger, stickier toe pads in order to better climb onto the smoother, higher tree branches.
  • Green anoles have also demonstrated their ability to evolve in real time in how quickly they can adapt to colder atmospheric temperatures.
  • In 2017, Harvard researchers released findings of their study of five different wild green anole populations living at different latitudes within their natural range in the U.S.
  • Their research involved putting the different green anoles in cooling chambers and seeing how cold they could get while still having enough coordination to right themselves after being flipped over.
  • They found the green anoles who lived in the southern-most latitude lost their coordination at about 11 degrees Celsius (52 F), while the green anoles from the northern-most latitude lost theirs at about 6 degrees Celsius (43 F).
  • And then came the winter of 2013-2014, which saw a polar vortex bring unusually cold temperatures to the southern U.S. – particularly to the area in which the southern-most green anoles in the study lived.
  • The southern-most green anoles in the study lived near the Texas-Mexico border and the polar vortex kept cold temperatures in that area for about a month.
  • The researchers took the opportunity to follow-up with those southern-most green anoles after that unusual winter and studied them in the cooling chambers again.
  • The researchers found that the green anoles who survived the polar vortex were now able to maintain their coordination to a low of 6 dgrees Celsius – and this was also now reflected in their DNA!
  • The researchers say genes in the green anoles’ livers along with the genes active in the nervous system and muscle function were found to more closely resemble those of their northern-most counterparts.
  • Green anoles are diurnal, meaning they are active during the day.
  • Green anoles are considered to be insectivores. They will eat anything that moves and that they can fit in their mouths – including, crickets, spiders, worms, ants, beetles and flies.
  • Green anoles have a short lifespan. In the wild, they can live around two years. While in captivity and with proper care, they can live between 6 and 10 years.

Leave a Reply