Paul Hetzler
The Advocate
To help explain how evolutionary change occurs over time, Charles Darwin used the phrase “survival of the fittest,” meaning that organisms with traits best-suited to their surroundings are more likely to reproduce and pass on those attributes to their offspring. For most animals, it’s a slow process that takes countless generations, but we see it in real time with microbes.
When an antibiotic is used for a bacterial infection, on occasion there may be a very few that live due to a gene variation that lets them break down the drug. The survivors then multiply to form a new strain of resistant bacteria, eventually giving rise to “superbugs,” like Methicillin-resistant Staphylococcus aureus. While this is not exactly natural selection, the same principal holds true: the fittest microbes (in this case, those than can withstand a toxin) survive.
But in popular culture, the concept of “survival of the fittest” is often conflated with physical fitness. Extreme sport competitions have adopted the phrase as their motto, and it was even the title of a 2018 reality TV show. In nature, however, the fittest is rarely the strongest.
Though survival is about finding enough food and water, it’s also about not becoming an entrée on someone else’s menu. For most animals fitness is dodging fangs and claws to live another day.
For a lot of species, fitness is blending in with the background. While I’m impressed by photos of seamless camouflage, a full-length film on it would be like watching paint dry.
On the other hand, I’d buy tickets to watch an animal immobilize attackers with glue-like projectile vomit, spew jets of hot acid at predators, or use its internal organs as projectiles.
Faking death works
Even faking death to avoid actual death is a theatrical affair.
If I were faced with something that wanted me for supper, like a zombie or a bear, my inclination would be to run. Dropping to the ground inert wouldn’t be top of mind. Yet, for a few critters, it seems to work. A well-known example is the Virginia opossum, also known as the American opossum, whose dramatic death re-enactments gave rise to the phrase “playing possum,” meaning to play dead, or to be a faker in general.
Found throughout southern Quebec and Ontario, as well as parts of British Colombia, this native marsupial has been expanding its range northward for decades. If you haven’t seen opossums in your area yet, you very well might in the future. Contrary to popular belief, it does not “play” dead. When threatened, an involuntary response called tonic immobility kicks in. Its muscles go rigid and its heart rate and respiration drop sharply.
Deeply unconscious in this state, it might be a tempting morsel to a carnivore, except that it also salivates profusely, urinates, defecates and releases a foul-smelling fluid from its anal glands. Apparently, no self-respecting predator wants to deal with that mess.
Other animals that exhibit this behaviour include reptiles, like the eastern hognose snake, which is native to Quebec, and at least one type of snake bleeds from its mouth as part of its act. Feigned death is known in a number of rodent and bird species, as well as insects. Tonic immobility can even occur in humans during acute traumatic events.
Some resort to goo
Chemical defense is an ancient survival tool used by microbes, fungi, plants and, of course, animals. The perfect example of this may be the striped skunk, abundant in southern Canada and found as far north as Nunavut and the Northwest Territories. Its weapon of choice is N-butyl mercaptan, related to the nasty stuff put in natural gas so that we can detect a gas leak. It’s very effective, and skunk encounters are memorable and unpleasant.
It’s a good thing the bombardier beetle is not the size of a skunk, or we’d all be in trouble. Distributed throughout North America, this 2.5-cm-long beetle shoots a boiling-hot corrosive cocktail to nail predators as far as 20 centimetres away. Without exaggeration, its concoction is literally 100 degrees F. They have two special abdominal chambers, one for hydrogen peroxide, and the other for hydroquinone. When needed, these are combined, along with a catalyst, and a violent reaction ensues, jetting a defensive liquid at about 40 kilometres an hour.
The northern fulmar, a gull-like sea bird native to the eastern Canadian Arctic, launches a different sort of cocktail. When confronted by a bird of prey like an Arctic skua, it vomits a stream of putrid, oily goo that it keeps on hand in a stomach compartment for just such occasions. This orange substance often clogs the would-be assassin’s flight feathers so it can’t effectively fly for a time. More importantly, the oil strips the natural waterproofing from the predator’s feathers, which means it can’t float and could easily drown.
When your profession is “prey,” you do whatever it takes to be fit enough to survive.