Species At Risk

Rayed Bean

(Villosa fabalis)


Rayed Bean
Rayed Bean occurrences map


The Rayed Bean is one of Canada’s smallest freshwater mussels, reaching less than four centimetres in length. The shell is oval-shaped, smooth, slightly shiny, and is green, yellow-green, or brown in colour with numerous wavy dark green lines.


In Canada, the Rayed Bean is found only in southern Ontario, in the East Sydenham River and a small section of the North Thames River. The species has been lost from Lake Erie and the Detroit River.


The Rayed Bean is typically found buried in sand or gravel in shallow, clear headwaters and riffle areas of small tributaries. It is often found buried among the roots of aquatic plants. The Rayed Bean filters water to find food, such as bacteria and algae. Mussel larvae are parasitic and must attach to a fish host, where they consume nutrients from the fish body until they transform into juvenile mussels and drop off. In Ontario, the fish hosts of the Rayed Bean include: the Brook Stickleback, Largemouth Bass, Greenside Darter, Johnny Darter, Rainbow Darter, Logperch, and Mottled Sculpin. The presence of fish hosts is one of the key features for an area to support a healthy mussel population.


The greatest threats to the Rayed Bean are invasive species, pollution and siltation, which occurs when too much soil washes into the river from nearby agricultural and urban areas. The Zebra Mussel, an invasive species from Europe, is a serious concern because it attaches to native mussels and can interfere with breathing, feeding, excretion, and movement. Conditions that threaten the fish hosts also threaten the Rayed Bean.


The Rayed Bean is protected under Ontario’s Endangered Species Act and the federal Species at Risk Act.

What You Can Do to Help the Rayed Bean

  • The Ministry of Natural Resources tracks species at risk such as the Rayed Bean. You can use a handy online form to report your sightings to the Natural Heritage Information Centre. Photographs with specific locations or mapping coordinates are always helpful. nhic.mnr.gov.on.ca
  • Report any illegal activity related to plants and wildlife to 1-877-TIPS-MNR (847-7667).
  • You can help improve mussel habitat and keep Ontario’s water safe and clean by maintaining natural vegetation next to creeks and rivers. The roots of plants reduce erosion and can stop soil from washing into the river. Fence off streamside areas to keep cattle (and their manure) out of the water. There are many other things that you can do to help reduce soil erosion and you might be eligible for funding assistance. For more information, visit the Ontario Soil and Crop Improvement Association: www.ontariosoilcrop.org.
  • Private land owners have a very important role to play in species at risk recovery. If you find Northern Madtom in a watercourse on or adjacent to your property, you may be eligible for stewardship programs that support the protection and recovery of species at risk and their habitats.
  • Invasive species seriously threaten many of Ontario’s species at risk. To learn what you can do to help reduce the threat of invasive species, visit: ontario.ca/invasivespecies ; www.invadingspecies.com ; www.ontarioinvasiveplants.ca ; and, www.invasivespecies.gc.ca .
  • Volunteer with your local nature club or provincial park to participate in surveys or stewardship work focused on species at risk.

Did you know?

The Rayed Bean is extremely rare throughout its range. It is known from fewer than 25 river systems in Canada and the United States.

Did you know?

Rayed Bean eggs hatch inside a special pouch in the mother’s gills called a marsupium. Here, the larvae are supported until they are ejected with a strong blast of water.

Did you know?

Mussels are indicators of environmental health. Since they have a complex life cycle, are long-lived (some species can live up to 100 years!) and eat by filtering water and its pollutants, mussels can provide a snapshot of how healthy our waterways are.

Did you know?

Aboriginal people harvested mussels for food and to create jewelry and tools. In the 1800s, massive numbers of mussels were harvested from the Grand River to create buttons. Millions were shipped out every year until the 1940s when plastic became more popular.

The Endangered Species Act

Contact your local ministry office

Often the best source of local information on species at risk is your nearest ministry office. Call with your questions or concerns.