Last Wednesday (September 10th) UBC’s biology 326 class went on our first invertebrate discovery field trip! The best part? We didn’t need to go to a remote island or to the tropics to find a wonderful diversity of marine life (though remote islands and the tropics would be pretty cool too…). We only had to walk the short distance from campus to UBC’s own Tower Beach!
We reached the beach at low tide with the objective of exploring the diversity of invertebrates, guided by a few simple questions: Is the number of different species (species richness) greater on the top or bottom of rocks? Are there more grazers such as snails and limpits on areas of rocks with rockweed present or areas with rockweed absent? Are there more and crabs under large rocks than small rocks?
Using these questions to guide us, we spent more time examining our surroundings than the average beach-goer probably would. We noticed a huge diversity of animals hidden in and among the barnacles and seaweed that usually dominate rock surfaces. For example, have you ever noticed isopods at your local beaches? These small crustaceans are similar to the familiar pill bugs you’ve probably seen on moist or decomposing wood. The individual in the photo to the left is able to camouflage against the rockweed in the rocky intertidal, making it easy to overlook!
Similarly overlooked but very charismatic are the limpits found on Tower Beach. These snail-like invertebrates often look like nothing more than a small protrusion from the rock to which they have secured themselves. They can be difficult to remove due to the strong hold they have on the rock with their muscular foot, but if you get a chance to see one up close, they are surprisingly cute!
Unfortunately, one of my favourite groups of invertebrates, the sea stars, were nowhere to be found on September 10th. This is perhaps due to the sea star wasting syndrome that has been plaguing the west coast (read more about the sea star wasting syndrome here: http://www.eeb.ucsc.edu/pacificrockyintertidal/data-products/sea-star-wasting/). Although this observation was slightly disappointing to me, I’m sure a lot of the other local invertebrates were glad to be rid of the sea stars, as they are notoriously vicious predators and will eat just about anything they can get their arms on!
In the end, it wasn’t the results to the specific questions we set out to answer that stuck with me the most (though some of my fellow students have summarized these results if you’re interested). It was the appreciation we gained for our local species through the exploration the questions promoted. I’m looking forward to more invertebrate-filled adventures through this semester, so stay tuned!