I’m so glad its Spring now, and we don’t have to worry about the snow or cold weather anymore. But for the most part, the winter is usually pretty mild for most of Vancouver. But at the Intertidal areas… it’s a whole different story. As a refresher, the intertidal is the area between the high and low tides. The climate at the intertidal experiences harsh changes in short periods of time. this means that wildlife living in these areas have to get used to this predicament!
Recently, we were interested in the life of these creatures in the intertidal. Particularly, how they fared at home during the cold winter and how changes in their choice of habitat can change their body temperatures. So, we went to Stanley Park over the winter to take temperature readings from boulders to get a sense of what the animals were experiencing.
We stumbled upon a few known predators of the lower intertidal…
At Stanley Park, by the infamous “Girl at the Westsuit” site, there were piles of Ochre sea stars (Pisaster) that were all clumped together. I believe these clumps were called aggregates. It seemed like some of the Pisaster on the edges were trying to squeeze into the middle… I wonder why… Anyways, we plucked off some of the sea stars at the middle and edges of the clusters to get a reading of their body temperature.
We also found dogwhelks (Nucella) around the boulders, they’re a type of sea snail! Some of the snails were near the bottom of the boulders, close to the sand, while others were closer to the tops of the boulders. Again, we took the shell and foot temperatures of these creatures from either the sand or tops of rocks. Did you know that dogwhelks prey on other shelled-molluscs by drilling into their shells and drink up the contents like a tasty soup? They actually secrete a chemical substance so that their dinner dissolves.
We eventually moved on to Sharon Cove in West Vancouver. At this site, we found another species of sea star, the mottled star or Evasterias. The Pisaster and Evasterias are often mistaken for one another. But a tell-tale sign of the Evasterias is that it has longer rays that taper. Here, we also took the temperature of Evaterias either in tide pools or on rocks.
After going back to the lab to run some tests, we found that the organism choice of habitat (ie. on rock vs sand) had an influence on their body temperatures! Now for the next step, we just have to test if cold weather could hurt them… stay tuned!
Here are some interesting links: