Have you ever wondered what lives at the bottom of the ocean? What creatures could bare the unthinkable conditions of freezing cold and dark water? They must look as ugly as their environment sounds, right?
Wrong! Some of the most stunning creatures on this Earth live here!
Bamfield Marine Sciences Centre’s skipper, John, took our Biology of Invertebrates class out to Trevor Channel near Wizard Rock and ran a mini “dredge” for us on February 11th. A dredge is an apparatus that is dragged along the bottom of the seabed which collects sediment and everything in it, including tons of stunning invertebrate animals! Here are a few of the amazing organisms we saw on this day:
Sea urchins are spiny invertebrates that are part of the Echinoderm phylum. They range from brown to green to purple and red in colour, and were named after the Latin word “ericius” meaning hedgehog. Can you see the resemblance?
Sea cucumbers have elongated cylindrical bodies, resembling a soft-bodied cucumber, and are also part of the Echinoderm phylum. The most common type is the “hairy” sea cucumber which can grow to 4 or 5 inches long (pictured). Sea cucumbers also play a key role in marine ecosystems as detritivores by recycling the organic material they consume.
Chitons are small oval invertebrates made of 8 separate shell plates encircled by a skirt called a “girdle” and belong to the Mollusca phylum. They are generally herbivorous grazers, although some chitons are omnivorous or carnivorous. Because of their good fossil records, chitons can be dated back to 400 million years ago!
These are only three of the countless beautiful invertebrates that call the seabed their home. And although our dredge was quite small and we returned all the organisms back into the same water afterwards, larger scale dredging is being done regularly around the world to keep waterways navigable but can have negative effects on aquatic ecosystems like the one we explored. Dredging can cause the composition of the sediments on the seabed to be altered, which can change the existing habitat of that area. This practice can also release toxic chemicals, such as heavy metals and PCB, originally buried in the sediments back into the water column. Some of the organisms that live in these areas cannot tolerate these changes in their environment and are at risk of dying out. Dredging can also cause a shorter-term negative effect by increasing the turbidity of the water, which can interfere with the spawning process of many organisms.
It’s not all bad though! New dredging companies are arising with goals of finding a balance between environmental challenges and economic demands, and have come up with some pretty amazing innovations to keep our aquatic ecosystems healthy.