iHerp_Australia_-_May_-_June_2018

What is venom?

Bianca op den Brouw is a PhD student at

the Venom Evolution Lab, University of

Queensland, where she is researching the

venom of the Viperinae clade. She is

involved in several additional venom-specific

side projects, including studies on King

Cobras and Australian elapids, and is

President of the UQ Herpetological Society.

Right: using an unconventional form of delivery system, the Mozambique Spitting

Cobra (Naja mossambica) can direct a spray of highly-potent venom with great

precision over a distance of up to three metres. The eyes of the potential threat are

deliberately targetted, and the venom can cause blindness or impaired vision.

Image by Stuart G Porter.

The problem with definition.

Venom. What is it, exactly? A few days ago, someone

asked me that same question. Being an enthusiastic

herper, you probably know the answer to that already,

right?

“Easy,” I hear you say. “A venom is injected; a poison is

ingested.” And you are right. Kind of. In reality, the

definition of what makes a venom - or more precisely,

what makes an animal venomous -- has been somewhat

of a bone of contention within the scientific community,

particularly across disciplines. So, if you are able to

answer that question with anything short of a caveat-

laden paragraph (or five), then you are doing better than

many of the researchers who actually work with the

stuff. So, what is it then?

A functional trait.

Venom is an adaptation which has evolved independently

in almost every major animal group. There are venomous

fish, cnidarians, invertebrates, mammals, and of course

reptiles. In fact, you are probably never more than a

stone’s throw away from a venomous animal. The role of

venom varies depending on the species, but it is usually

employed in either a predatory or defensive context. This

makes it a functional trait; a kind of evolutionary inter-

face between organism and ecosystem, the use of which

provides a direct contribution to the fitness of the

venomous animal. This facilitated the explosive diversifi-

cation of many of these venomous animal groups. That

is, the emergence of venom ultimately gave these

species a higher likelihood of success in adapting to and

persisting in new and existing ecosystems, increasing

their likelihood of survival and reproductive success.