Why did it have to be snakes!
Let's put the fictional Indiana Jones aside and acknowledge a real and adorable snake mating ball. Check out this video of the annual snake convention in the limestone caves of Narcisse in Manatoba, Canada. Periscope up!
Cute and small garter snakes were thought to be non-venomous until recently. Not true. They produce a neurotoxic venom, but lack an effective means of delivering it to human-sized animals. I thought this was similar to daddy long-legs spiders, as urban legend holds their venom is more potent than a black widow but their fangs too tiny to pierce human skin, but learned that thier venom is not actually very potent. In contrast, I wouldn't want to stumble upon this anaconda breeding ball, though the snakes are probably too busy to care. It brings back too many bad memories of the 1997 movie, in which Jon Voight tried so hard to channel Christopher Walken that Jennifer Lopez seemed to act naturally. Scary stuff indeed.
But let's talk about heat. I love that masses of snakes help each other survive the -40 temperatures in winter by sharing subterranean limestone caverns. Bees do this, too. There may even be heater bees with the specialized job of using their flight muscles to finely tune the hive temperature instead of for flight. But the snakes reminded me of the communal nests birds like weavers share, keeping them cool in the summer and hot in the winter.
I learned about this in grad school when one of my friends lost power to his apartment because the feral parakeets of Hyde Park built a communal nest on the transformer outside his window. It kept them warm in the Chicago winter, until it caught fire. Strangely enough, parakeets causing transformer fires is a common occurrence nationwide. Ditto for weavers.
I love it when science is better than science fiction. Or, in the words of Indiana Jones (via Jasper Rine, who loves this quotation):
Nothing shocks me. I'm a scientist.
- Indiana Jones and the Temple of Doom