Lee Kong Chian Natural History Museum

Fun Facts: All About Reptiles

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Fun Facts: All About Reptiles

Today (October 21) is Reptile Awareness Day! On this day, we would like to shed light on four uncommon facts about our scaly friends. 😉

1. Not all snakes swallow their prey whole

Contrary to popular belief, some snakes rip their prey into smaller pieces instead of swallowing them whole. Scientists observed this unusual behaviour in the cat-eyed water snake (Gerarda prevostiana) that is native to Southeast Asia.

The cat-eyed water snake, Gerarda prevostiana. Photo credit: Kelvin Lim.

In the study published in the Biological Journal of the Linnean Society, Dr. Bruce Jayne from University of Cincinnati, along with Dr. Harold Voris from the Field Museum of Natural History, Illinois, and Prof. Peter Ng from LKCNHM examined the feeding habits of crustacean-eating snakes.

They found that the cat-eyed water snakes are capable of attacking and devouring crabs that are up to five times larger than their jaw size.

However, they are picky about their food – only consuming crabs when they are freshly moulted (i.e., soon after shedding their hard outer shells). They begin their meal with a bite that tightly grasps the crab’s main body (known as the carapace). Next, they proceed by winding their body in a loop around their prey, and pulling the prey through the loop repeatedly until it rips apart into smaller pieces.

After which, they eat the smaller pieces. If the prey’s carapace is still larger than their jaw can accommodate, sometimes they will rip the legs and consume them one by one.

For a more in-depth explanation, check out the National Geographic article (click here) and the following video:

2. Chameleons don’t change their colour to camouflage themselves

Often called the ‘masters of disguise’ for their ability to change colour, chameleons do not actually change colour to blend into their surroundings. Instead, most colour changes reflect a change in their mood, or serve as a means of communication.


An unidentified chameleon species. Photo credit: Pollydot on Pixabay.

For example, the panther chameleon (Furcifer pardalis) turns into the ‘warning colours’ of red and yellow when they are agitated or are getting ready to attack. Some types of male chameleons will also turn into brighter colours when they are trying to attract a mate.

Chameleons also tweak the colour of their skin in response to changes in temperature. In hot weather, a chameleon may change their skin to a light colour that helps reflect heat from the sun. On the other hand, in cold weather a chameleon may turn a dark colour to absorb more heat.

Also, some chameleons can only change within a limited spectrum of colours, such as green, brown, or gray. Others have the ability to change to a wider variety of different colours such as pink, blue, red, orange, green, black, brown, yellow, turquoise, and purple.

3. Snakes and lizards use their tongues to smell

The common sun skink, Eutropis multifasciata. Photo credit: Kelvin Lim.

Although snakes and lizards do possess nostrils, they are mainly used for breathing. These reptiles smell primarily using their tongue and a sensory organ known as the Jacobson’s organ, which is situated in their mouths.

Snakes and lizards pick up smell by flicking their tongues into the air, collecting tiny chemical scent particles. When they retract their tongues, these chemical particles are then transferred to the Jacobson’s organ via two grooves in the roof of their mouths. From there, this chemical information is sent to the brain, where it is processed.

The forked shape of the tongues of snakes and most lizards also help ‘point’ them in the correct direction, literally. These reptiles decide which direction to move in based on the amounts of chemical information collected on either side of their forked tongues.

For example, if the left tip collected more chemical scent particles compared to the right, then the source of the smell must be located somewhere to the left. This helps them follow chemical and pheromone trails left by prey and potential mates, as well as avoid predators lurking nearby.

4. Temperature determines the sex of crocodiles and most turtles

The sex of most species of animals is determined at the point of fertilisation. However, the sex of crocodiles and most turtles is dictated after fertilisation – during the incubation period. During this time, the temperature of the environment surrounding the developing eggs influences the sex of the resulting offspring. This is known as temperature-dependent sex determination.

For example, researchers have found that when the eggs of red-eared slider turtles (Trachemys scripta elegans) are incubated at 26°C, the resulting hatchlings will be male. When incubated at a slightly higher temperature (32°C), the hatchlings will be female. Incubation at temperatures between these two extremes will produce a mix of male and female baby turtles.

Red-eared slider turtles Trachemys scripta elegans. Photo credit: Kelvin Lim.

Research has also found that the warmer the sand that surrounds the eggs during incubation, the higher the ratio of female turtle hatchlings. However, increased temperatures resulting from climate change could result in skewed ratios of male to female hatchlings, to potential detrimental future impacts.

A study of green sea turtles (Chelonia mydas) in the Pacific found that in the northern Great Barrier Reef — one of the largest populations of sea turtles in the world—the females outnumbered their male counterparts by a ratio of 116 to 1. On the other hand, in the southern reef where temperatures have not increased as drastically, the ratio of females to males is 2 to 1.

 

References

Badger D (2003) Lizards: A Natural History of Some Uncommon Creatures – Extraordinary Chameleons, Iguanas, Geckos, & More. Voyageur Press, 160 pp.

Bates M (2014) How Do Chameleons Change Colours? https://www.wired.com/2014/04/how-do-chameleons-change-colors/. (Accessed 2 August 2018).

Bull JJ (1980) Sex determination in reptiles. The Quarterly Review of Biology, 55(1): 3–21.

Burrell G (2015) Why Do Snakes Have Forked Tongues? http://thescienceexplorer.com/nature/why-do-snakes-have-forked-tongues. (Accessed 2 August 2018).

Edmonds P (2015) Chameleon Colors Reflect Their Emotions. https://news.nationalgeographic.com/2015/08/chameleon-colors-reflect-their-emotions/. (Accessed 2 August 2018).

Grava KA (2011) Snakes, Lizards, and Tongues. https://today.uconn.edu/2011/04/snakes-lizards-and-tongues/. (Accessed 2 August 2018).

Jayne BC, Voris HK & Ng PKL (2018) How big is too big? Using crustacean-eating snakes (Homalopsidae) to test how anatomy and behaviour affect prey size and feeding performance. Biological Journal of the Linnean Society, 123(3): 636–650.

Jensen MP, Allen CD, Eguchi T, Bell IP, LaCasella EL, Hilton WA, Hof CAM & Dutton PH (2018) Environmental warming and feminization of one of the largest sea turtle populations in the world. Current Biology, 28(1): 154–159. DOI: https://doi.org/10.1016/j.cub.2017.11.057.

Main D (2018) This Snake Rips Its Prey Into Pieces, Instead of Swallowing it Whole. https://news.nationalgeographic.com/2018/04/snakes-reptiles-animals-predators/. (Accessed 2 August 2018).

Welch C (2018) 99% of These Sea Turtles Are Turning Female—Here’s Why. https://news.nationalgeographic.com/2018/01/australia-green-sea-turtles-turning-female-climate-change-raine-island-sex-temperature/. (Accessed 2 August 2018).