Understanding Venom

There’s no escaping the fact that many of the types of animals kept as exotic pets have something of a reputation for being venomous – much to the concern of the reluctant partners, friends and parents of would-be owners!

Of course, some of this is deserved. There certainly are some kinds of snakes, spiders, scorpions and even frogs in the world which can kill you – but you’re not going to find them on sale down at your local pet shop. Never-the-less many of the creatures you will see being offered for sale do still have a poisonous bite or sting – albeit a mild one – so if you’re going to keep these kinds of pets, it’s probably a good idea to know something about the facts and fiction of venom.

What Is Venom And Why Do Some Animals Have It?

There are two general types of venom and, in evolutionary terms, they originally arose to meet two particular needs – capturing prey and defence – although there is now a bit of a cross-over.

The first kind of venom – found in those kinds of predators which use it to subdue their prey, such as snakes and scorpions – could probably be best described as toxic saliva. Saliva itself contains enzymes which are necessary to break down and digest food and some animals gradually developed a way of injecting their saliva into their victims to speed up the process. Spiders are one of the best examples of this approach; they inject digestive venom into their prey, wait until it has done its job and then suck back the pre-digested soup from the animal’s body – hence the dried up insect husks you find in spider webs, which are all that remain of the insect’s insides after the digestion!

The second sort of venom has evolved from natural skin secretions, with the South American Poison Arrow Frogs probably being the most well known example of this, although other amphibian species are also poisonous to some degree. Most are not harmful to humans but some, such as the Cane Toad (Bufo marinus), produce a substance which is very powerful indeed.

These kinds of venom are intended for defensive purposes; if you are a small, soft and relatively slow moving creature, tasting bad can be a great way to dissuade a predator from seeing you as a potential easy meal. The bright colours of many animals – including the likes of Poison Arrow Frogs and the European Fire Salamander ( Salamandra salamandra) – advertise the fact, to warn other animals of their unpalatable natures in advance.

Which Other Kinds Of Animals Are Venomous?

Venom is surprisingly widespread in the animal kingdom and many creatures have developed their own versions of these “chemical weapons.”

All spiders are venomous – including the ones native to Britain – and so are all of their relatives, the scorpions, though obviously many kinds either cannot bite through our skin, or don’t produce any real symptoms if they do. Some species found in the warmer parts of the globe are highly dangerous to man, but they’re obviously not candidates for the pet market.

Although many people are firmly convinced that all snakes are instantly deadly, contrary to this popular belief, only around one in three of the world’s species is poisonous, and only a very small number of these pose any serious threat to humans.

Snakes, spiders and scorpions all originally developed their venoms to help them catch and eat their prey; however, if threatened, they may make use of this natural weapon to defend themselves – although most will typically try to escape first, rather than waste venom on a “non-meal.”

Deadly Venom

In any discussion of venom, sooner or later, someone is inevitably going to ask which is the most deadly snake or spider – but it’s a difficult question to answer. Ranking the potency of the various venoms of the world in terms of number of people they can kill per drop is fairly simple, but in many ways it misses the bigger point.

The venom of sea snakes, for instance, is widely accepted to be some of the most lethal, drop for drop – and yet few human fatalities are recorded, largely because on the rare occasions sea snakes do bite people, they almost never inject any venom. By contrast, the Puff Adder ( Bitis arietans) is an ill-tempered beast and regularly causes all manner of problems in the parts of Africa and the middle east where it is found – despite having a technically less potent venom.

Even two bites from the same kind of snake can have decidedly different outcomes; one that has recently fed – and so used up its immediate supply of poison – can produce no ill effects, while one from a fully armed member of the same species can be lethal.

It’s not just amongst the snakes that the issue gets complicated; the potency of Poison Arrow Frog venom, for example, depends on the poisonous insects they eat in the wild, their captive-diet rendering them innocuous.

For many exotic pet keepers, these biological conundrums are part and parcel of their attraction to these kinds of animals – and there’s one thing for sure, understanding venom is every bit as complex as it is fascinating!