Despite my title most millipedes don’t actually have a thousand legs, instead the number is more around 100-200, but they do look like they could have that many. These adorable little Diplopods are found under logs and in the forest floor eating away at dead plant matter and wood. Because they are completely herbivorous they often use poisonous substances and bright colours to deter predators from eating them. A common local example is the Yellow Spotted Millipede (Harpaphe haydeniana subsp. Haydeniana ).
You will often see this millipede in the summer if you go to a park here in Vancouver. The bright yellow spots tell predators that they have toxins, in this case cyanide, that might make things end not so pleasantly for the predator. However, if you’re feeling brave you can pick one of these cute little bugs up, gently shake it around a bit and you’ll be rewarded with the delightful scent of almond extract. That’s right, cyanide smells like almond extract, even though it might be correct to say almond extract smells like cyanide.
For my independent project I worked with millipedes from the family Julidae. Due to the lack of knowledge of millipede identification I was unfortunately not able to determine the species of the millipedes (here is a list of species in BC). I had no idea millipedes were so understudied and I personally don’t understand why more people wouldn’t want to work with these adorable creatures!
I decided to freeze millipedes in order to understand more about if and how millipedes survive winter temperatures. The weather is a lot more mild here in Vancouver but where I grew up in the interior of BC the winters are a lot more harsh. I found out that it takes most millipedes 2-3 years to mature into adulthood, therefore the millipedes must be tolerant of freezing temperatures.
First I put the millipedes into two different incubators and then I tested the supercooling point, survival at temperatures below zero (from -3 to -11) and the time it took for millipedes to recover from being held at 0⁰C. Supercooling is when a liquid is cooled below it’s freezing point but doesn’t become solid. The point where this occurs in an animals body is theorized to be the coldest temperature an animal can survive to. However, many insects have compounds in their body that act like anti-freeze to allow them to freeze and still survive. I found that the temperature millipedes were first exposed to had no effect on their ability to survive freezing. And survive freezing they did! Even at temperatures as low as -5 I had some millipedes up and crawling around in minutes.
This amazing ability to overwinter isn’t only found in invertebrates. The wood frog is able to completely recover from winter temperatures also. You can check out an interesting video about it here.
So take home message think millipedes are adorable and people should study them more.