When we think of the rich biological diversity in the Gulf of St. Lawrence, what mostly comes to mind are the whales, the seabirds, and the fish (some of which end up on our tables). What is less well known, or not known at all by many people, is that the cold waters of the Gulf are blessed with a multitude of organisms with surprising shapes and colors. Those organisms are animals with often very particular ways of living. They belong to the invertebrates, meaning they have neither a spinal column nor internal skeleton to support them. Generally speaking, these animals are less evolved than vertebrates, but their level of complexity varies from one group to the next.
Their abundance and their diversity
Invertebrates in the Gulf of St. Lawrence consist of more than 3,000 species spread over 29 branches. By comparison, fish in this ecosystem add up to only 140 species. The wide variety of habitats that they colonize accounts for their great diversity and their abundance. The majority colonize the seabed, some of them living on the surface of sediments, others buried inside them. They include sponges, sea anemones, starfish, sea urchins, sea cucumbers, lobster, crabs, shrimp, shelled mollusks, and worms of all kinds. A good number of other species, meanwhile, live in suspension and more or less drift in the water column. These comprise the plankton species like jellyfish, krill (small shrimp) and numerous tiny crustaceans, for example the copepods. Some invertebrates also live like fish and swim actively between two masses of water: certain mollusks, including cephalopods such as squid.
What purpose do invertebrates serve in the marine environment?
The invertebrates play a number of ecological roles in marine ecosystems like that of the Gulf of St. Lawrence. First of all they provide food for a host of animals that are higher up on the food chain: other invertebrates, small and large fish, sea birds and marine mammals. When we realize that a whale consumes from two to four tons of krill every day, we quickly understand the degree to which these invertebrates are essential to marine life and why they must be so abundant. Many marine invertebrates, particularly those who live on the bottom and in sediments, also play a vital role by contributing to the breakdown and recycling of organic matter in the ecosystem. Others such as filter-feeding mollusks help in keeping the water clean by preventing blooms of microscopic algae that could affect water quality.
Marine invertebrates at the Biodôme?
The Biodôme has always presented marine invertebrates in its Gulf of St. Lawrence ecosystem. Starting in the fall of 2014, new habitats will enable us to display a greater diversity of these organisms for visitors and to share more knowledge about their biology and their ecology, providing people with a greater awareness of the complexity and the fragility of this marine ecosystem.