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Life Underwater Series: Life of the Clam

Carina Nunes

Life of the Clam: the ultimate survivor

The clam is a fascinating benthic macroinvertebrate that in most cases will undergo metamorphosis involving larval, juvenile and adult stages. Clams reproduce both asexually and sexually as some species are hermaphrodites, having both female and male reproductive systems. Today we will explore: What happens after the clam leaves the safety and familiarity of the water. And what does the clam tell us about our aquatic environments? To explore these questions, we’ll start at the very beginning-- when the clam eggs are first laid.

For some species, mating occurs when the male clams release his sperm into the water and it is drawn into the female bivalve through her siphons. The female‘s eggs are produced internally and are ready for fertilization to occur. The larvae will then develop inside the shell of the female and will be released into the environment where they can settle along the bottom of the water body. In species that are hermaphroditic, they can select who will take on the male or female role in reproduction.

The clam’s role in freshwater ecosystems is critical. Mussels, a group of bivalves, are an important species that indicate the health of aquatic systems because they are sensitive to a range of environmental factors including the health and diversity of local fish communities and levels of dissolved oxygen in the water (Species at Risk Public Registry, 2018). Additionally, clams have a variety of predators that include numerous types of fish, birds, crayfish, frogs and a variety of mammals that include otters, raccoons and muskrats.

Out of water bivalves are fascinating creatures. Clams cannot breathe in an air environment, however, when a drought occurs clams can survive anywhere from months to years out of water. This is possible because they are able to shut down all bodily processes except those deemed essential for survival that can continue to be carried out without oxygen. During this period a clam will open up and only release waste that has built up when necessary to prevent the loss of moisture. The fascinating part comes into play when after all this time, once put back into an aquatic environment, after a short span of 12 hours, the clam will have returned back to normal, exhibiting all the normal bodily processes after having increased its oxygen levels.

Fun Fact:  Freshwater mussels have been used in past studies to determine the level and degree of contaminants in aquatic ecosystems (Species at Risk Public Registry, 2018).

Fun Fact: Bivalves are similar to trees in that they can be aged by counting the number of growth lines on their shells, just as you would count the rings of a tree trunk.

Fun Fact:  There are about 20,000 living species of clams worldwide with about 260 species native to North American freshwaters and about 6 non-native or introduced species in North America.

Interested in learning more about benthic macroinvertebrates and how they can be used to measure the health of rivers and streams? Be sure to follow EcoSpark’s social media to stay updated on our Changing Currents program and our other citizen science and environmental education programs.

References  

Carina holds a Bachelor of Honors in Environmental Studies and a diploma in Ecosystem Technology, both of which developed her interest in using geographic information systems to communicate about complex issues, such as climate change. In her role as Lead Environmental Educator, Carina designs geospatial education tools for EcoSpark’s citizen science programs. When outdoors in the field, you will often find her streamside identifying aquatic critters, communicating her enthusiasm for the outdoors, and demonstrating her dedication to stewardship practices with youth and adults throughout the GTA.