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.