Special thanks to Publisher of The North Island Eagle, Kathy O’Reilly Originally printed Friday, September 28th in The North Island Eagle
The rains have started, the ocean mist has begun to roll up towards our coastal villages, and the warm rays of the Island sun are reaching down and brushing our necks and cheeks with brisk dancing fingers. Fall, my favorite time of year, has emerged. As the summer draws to a close, I think most of us will be exchanging our shorts and T-shirts for jeans and sweaters (but please not the weird Christmas sweaters, those give me nightmares). As we leave the beach for a cozy fire, warm drinks, and family dinners, I thought we could feature one more tidal pool creature before we shift to our winter writing – the often overlooked chiton.
Smooth, and usually found stuck to rocks or a gravel sea bed, the chiton, or Polyplacophora as the scientists call it, is a mollusk (i.e., meaning an animal with a soft segmented body and sometimes a hard outer shell) and closely related to snails, slugs, mussels, and octopus. Its back has a series of 8 “plates” that overlap like a medieval knight’s armour. These plates form its outer shell and provide protection from other predators (like seagulls, crabs, and sea stars) while also allowing the chiton to flex its body upwards as it slowly travels along the rocky shores. Encircling the shell is a soft membrane known as a “skirt” or “girdle”. The chiton is suction cupped down by use of one large “foot”. When dislodged from its host surface, the chiton can curl into a ball in an effort to protect its soft snail like body. Warning! The suction of a chiton’s foot is extremely strong; if you try to pry it off a rock you can kill it! So, pat softly, take pictures, and leave this little guy be.
Chitons have been found in fossils dating back to prehistoric times. In fact, some chitons are referred to as “living fossils” which give us a glimpse into an era when dinosaurs roamed the earth. They live in the ocean’s waters all over the world with just over 900 species identified. Here in BC, there are approximately 48 species of chitons that have been noted and scientific efforts to locate new species are ongoing every year. BC is home to the largest chiton in the world, called the “gumboot chiton” or “giant western fiery chiton”. The gumboot chiton has a red outer shell and can grow up to 14 inches long and weigh over 4 pounds! It lives up to 40 years, but no, it doesn’t actually wear a gumboot! Although the massive foot of this giant armoured slug like dinosaur is probably where it got its name. But wait, it gets weirder…
Most chitons eat plants, kelp, and other marine vegetation. However, algae growing on rocks are the favorite food. And how does one eat algae off of hard rock surfaces you might ask? With steel teeth of course! On the underside of the chiton “foot”, right at the head part, there is a small mouth that has a tongue called a “radula”. The chiton radula is ribbon like and covered in teeth that are tipped in magnetite (i.e., an iron metallic mineral) that helps it literally lick rocks its whole life. While the chitons are licking rocks, we humans have decided that licking chitons is probably only best if you’re starving. Although they have been found edible, here in the Pacific Northwest, the tough rubbery texture has led many to avoid eating the massive sea foot (Peeeew! Somebody tell it to put the sock back on!).
So there it is, mystery solved. We might not have a gumboot wearing dinosaur but we do have a giant armoured slug like creature with steel teeth! And that concludes this summer’s tidal pool series. There is so much life in our local salty pools I just could not get everyone in this year. But, if you stick around, we might just get to pick up next summer where we left off today – the amazing natural world of even the smallest ocean spaces. To loosely paraphrase the infamous Baltimore Grotto caving group, remember friends, kill only time, leave only foot prints, take only memories.
Bryce Casavant is a former BC Conservation Officer and Doctoral Candidate at Royal Roads University. He writes for the Eagle from his home on Vancouver Island.