Vertebrates: Venomous Lizards

Welcome back to evolution of venom, in today’s blog topic, we will be coving other reptiles that use venom. A brief recap: we covered on what vertebrates are, what are snakes and how they use their venom.

 

Venomous lizards are restricted to two species, the Gila Monster (Heloderma suspectum) and the Mexican beaded lizard (Heloderma horridum). The Gila Monster is a heavy, slow moving lizard and is the only venomous lizard in the United States. The Mexican beaded lizard is slightly larger than the Gila Monster and is found in Mexico. Both species are Helodermatids, which are large, stout- bodied lizard with short legs designed for digging and they have a large head with powerful jaws (West et al, 2014).

 

The venom glands are located in the lower jaw with enlarged, grooved teeth located above the glands. Their jaws are designed to bite on to their prey and maintain a vice grip on the prey. Their venom is mainly for defensive purpose and human deaths are rare, the venom mostly causes a drop in blood pressure causing hypotensive shock (West et al, 2014). Below are 2 images on what each lizard looks like.

Gila Monster (Heloderma suspectum)

By I, Blueag9, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2292282

Mexican beaded lizard (Heloderma horridum)

By David Rubin - originally posted to Flickr as 00254-20.07.2007-Zoo, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=8350359

 

Komodo dragons (Varanus komodoensis) are the world’s largest lizard weighing up to 90 kg and a length of 3 m. It is found on five small islands in Eastern Indonesia. Komodo dragon’s saliva contain bacteria that can cause sepsis and infection allowing the Komodo dragon to follow the weaken prey until they collapsed and died from their infection. There is a debate on if the Komodo dragon’s saliva is venomous or not (Bull, 2010).

 

Komodo dragon (Varanus komodoensis)

By Mark Dumont - Flickr: There Be Dragons, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=25935468

 

 

In next week blog, we will be covering mammals that use venom, below are the articles that were used in this week's blog.

 

References

Bull, J.J., Jessop, T.S. & Whiteley, M. 2010, "Deathly drool: evolutionary and ecological basis of septic bacteria in Komodo dragon mouths", PloS one, vol. 5, no. 6, pp. e11097

 

West, G., Heard, D. & Caulkett, N. 2014, "Venomous Reptile Restraint and Handling" in John Wiley & Sons, Inc, Hoboken, NJ, USA, pp. 337-350.

 

Picture references

https://en.wikipedia.org/wiki/Komodo_dragon#/media/File:Komodo_dragon_with_tongue.jpg

https://en.wikipedia.org/wiki/Mexican_beaded_lizard#/media/File:Heloderma_horridum_-Zurich_Zoo-8a.jpg

https://en.wikipedia.org/wiki/Gila_monster#/media/File:Gila_monster2.JPG