Bites, Stings, Spines, and Spurs – Venom Delivery


[RATTLE]>>MARK SIDDALL: There are numerous ways in which to deliver venom. [WHIP CRACK]>>SIDDALL: But it’s not infinite. It tends to really boil down to what end of the animal we’re talking about. So, for example, venoms can be delivered with
a bite. In which case, there’s usually fangs. And associated with those fangs there are
usually some sort of modified glands—either modified salivary glands or some other gland—that produces the toxin. Let’s take, for example, the pit vipers. The
pit vipers have hollow teeth just like a hypodermic needle that they use for delivering venom. There are other snakes—for example the cobras—they still have fangs, but the teeth have deep grooves in them and those grooves serve
to deliver the venom down their length with a bite. And then there’s something like the Gila monster
in the desert Southwest of the United States. They don’t have fangs, but they do have teeth
and those teeth are incredibly strong. If a Gila monster bites, the force of the
bite itself causes two glands right underneath the lips—if lizards had lips—to squeeze
and press the venom out along the teeth and delivering it that way. [BUZZING]>>SIDDALL: Another way that animals deliver venom—and this happens to be particularly the case amongst the insects and other arthropods—is through
what we would call a sting. Which just means that the sharp thing is at
the other end. A wasp, an ant, a bee, scorpions— they all have stings. That sharp thing is really an anatomical feature
that first existed for the purposes of depositing eggs. But what if the thing delivering venom is
somewhere else on the body? And this actually happens in a lot of different organisms. People are often surprised to learn that there
are venomous mammals. The duck-billed platypus in Australia, for example, is a venomous mammal.
It has spurs on its hind legs, used not for defense so much as combat between males competing
for females. And then you have spines. If you step on a stonefish that’s buried in
the sand, a spine—hollow in the middle—will go up into the heel of your foot and the pressure
of your foot will squeeze the gland, forcing the venom up and either making you very sick
or in some rare cases actually killing you. Those spines are really just modifications
of the normal dorsal fin spines that you see on other fish. Some of the earliest animals to ever exist
on this planet were the Cnidarians. This includes jellyfish. It includes sea anemones. They’re called Cnidaria because they have
cnidocysts. These are tiny, tiny little stinging cells, sometimes only in one part of the body,
like the tentacles and sometimes all over the body. When brushed or when coming in contact
with something of the right chemical make-up, those cnidocysts will forcibly explode, extruding
a long spine, often with little barbs on it, and very frequently delivering a venom. A lot of animals spend a lot of energy and
time trying to hide or run away from predators. But one of the great things about being a
poisonous animal is that everybody sees you and they know not to take a bite.

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6 thoughts on “Bites, Stings, Spines, and Spurs – Venom Delivery

  1. Bites, stings, spines, and spurs—venomous animals have evolved a variety of mechanisms that deliver toxins to would-be predators and prey. In this video, Museum Curator Mark Siddall discusses some of the anatomical features you'll want to avoid! Learn more in the current exhibition, The Power of Poison: http://bit.ly/1uKW8kS

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