Venomous snakes are species of the suborder Serpentes that are capable of creating venom, which they utilize to kill their prey, for defence, and to aid with the digestion of their prey. Venomous snakes are classified as venomous because they are able to produce venom. In most cases, the venom is administered through injection using fangs that are hollow or grooved; nevertheless, there are certain poisonous snakes that do not have well-developed fangs.
Although most people are aware that some types of snakes pose a threat while others do not, not everyone is aware of the characteristics that differentiate poisonous snakes from those that are not. There are a lot of outdated standards in conventional medicine, and some of them might lead laypeople to make decisions that could put their lives in danger. There is a common misconception that all poisonous snakes have elliptical eyes. However, dangerous species can have pupils that are round, elliptical, or even keyhole-shaped.
Round pupils
Some of the most dangerous snakes on the globe belong to the family Elapidae. These snakes, which all have round pupils, include taipans (Oxyuranus sp.), cobras (Naja sp.), and mambas (Dendroaspis sp.). In addition to this, the pupils of sea snakes (family Hydrophiidae) are spherical, and their venom is quite potent. Coral snakes (Micrurus ssp.), which are native to North America, have pupils that are spherical. This may be the basis of the urban legend that there is a link between pupil form and poison.
Variables influencing pupil form
There is no connection between the presence or lack of venom and the shape of the pupil, and dangerous snakes can have any number of different pupil configurations. Herpetologists believed for a long time that the elliptical pupils of snakes were some sort of adaptation that helped them to see better in low light. The researchers revealed that ambush hunters have pupils that are often vertically elliptical by analyzing the pupil shapes, activity patterns, hunting techniques, and phylogeny of different snakes. On the other hand, actively searching snakes have pupils that are spherical. When looking at animals moving on a horizontal plane at varied distances, those with vertical pupils had greater eyesight than those with circular pupils. There was a correlation between nocturnal species and vertical pupils, although it was not as substantial as the correlation seen with ambush hunting behaviors.
Elliptical Pupils
It is not uncommon for many distinct snake lineages to have pupils that are elliptical or catlike in shape. Elliptical pupils are shared by all vipers and pit vipers, including copperheads (Agkistrodon contortrix sp.) and rattlesnakes (Crotalus ssp.). The majority of vipers and pit vipers are ambush hunters, meaning they wait for their prey to come to them rather than actively pursuing it. These findings are in line with the findings of a research that Brischoux and colleagues conducted in 2010. In addition, the pupils of certain species of rear-fanged colubrids, such as the mangrove snake (Boiga dendrophila) and the brown tree snake (Boiga irregularis), are vertical and catike.
Unusual Pupils
The pupils of vine snakes belonging to the genus Ahaetulla are distinctive among snakes in that they are extended in a horizontal direction and have the form of a complicated keyhole. It is believed that they have a part in the ability of these snakes to focus, since they have very strong binocular vision in comparison to the eyesight of other snake species. Vine snakes, unlike vipers and cobras, do not have well-developed fangs; rather, they have larger, grooved teeth at the back of their jaws. Vipers and cobras have well-developed fangs. Vine snakes employ their venom largely for the purpose of capturing prey, and bites from these snakes normally do not result in major medical problems in people.
