The peculiar life of Vancouver Island’s Pacific sand dollar

Pacific sand dollars are a local species which belong to the same group as sea urchins. While alive, they are covered entirely by thousands of densely packed, short and slender spikes. (Photo courtesy of Louise Page)Pacific sand dollars are a local species which belong to the same group as sea urchins. While alive, they are covered entirely by thousands of densely packed, short and slender spikes. (Photo courtesy of Louise Page)
Pacific sand dollars are a local species which belong to the same group as sea urchins. While alive, they are covered entirely by thousands of densely packed, short and slender spikes. (Photo courtesy of Louise Page)Pacific sand dollars are a local species which belong to the same group as sea urchins. While alive, they are covered entirely by thousands of densely packed, short and slender spikes. (Photo courtesy of Louise Page)
A zoomed-in look at the spikes of a Pacific sand dollar, a local species which belong to the same group as sea urchins. While alive, they are covered entirely by thousands of densely packed, short and slender spines. (Photo courtesy of Louise Page)A zoomed-in look at the spikes of a Pacific sand dollar, a local species which belong to the same group as sea urchins. While alive, they are covered entirely by thousands of densely packed, short and slender spines. (Photo courtesy of Louise Page)

Sand dollar exoskeletons are often collected along the beaches of Vancouver Island, but one might not realize that prior to washing up on shore came an entire curious lifetime.

Pacific sand dollars are a local species which belong to the same group as sea urchins. While alive, they are covered by thousands of densely packed, short and slender spikes. Unlike their sharp, unapproachable, long-spiked sea urchin relatives, sand dollars have a more velvet-like covering.

“The entire surface of a sand dollar is covered by its skin, all of the spikes even have a very thin layer of skin,” said Louise Page, who teaches invertebrate biology and marine biology at the University of Victoria. “When they die, the skin decomposes, the muscles attaching the spines decompose and the spines fall off. So when you pick a dead sand dollar up on the beach, it’s a white disk and you can no longer see the little spikes.”

The spines of a sand dollar allow them to move, and bury themselves under sand and mud. The spines wave back and forth, which pulls their body in and out of the sand.

The beautiful flower shaped pattern you see on a dead sand dollar, is a pattern revealing where specialized gills once attached.

“The flower pattern marks the point where specialized gills extend to the surface for gas exchange. It’s how they breathe,” said Page.

READ ALSO: Rare bird spotted at Vancouver Island backyard feeder

Sand dollars have a rather bland diet – in a human’s opinion – feeding primarily on, you may have guessed it… sand. To be more specific, they eat and digest grains of sand, but each grain is coated with a film of organic matter, which provides nourishment for their little bodies.

“An interesting thing about Pacific sand dollars, which is very unusual, is that they will also stand up… and then when water flows past them, they can capture small zooplankton in the water and feed on it,” noted Page.

Life out there as a larvae in the big ocean is risky, to say the least. The larvae of sand dollars don’t look anything like their adult self, said Page, and the time until metamorphosis generally takes about four to six weeks.

When it comes time to undergo metamorphosis, the larvae will settle on the sand, and from there, a sand dollar pops out of the left side of its juvenile body. The rest of the larvae body then degenerates.

Essentially, after being whisked around in the ocean for weeks, the fortunate larvae will smell adults of the same species, and then settle at that site.

“Where adult sand dollars are living is a great place for the juniors to recruit into. This is because there is a species of tube-dwelling crustaceans called ‘tanaids’ in the sand, which feed on newly metamorphosed sand dollars,” said Page.

“It turns out that the burrowing activity of adult sand dollars, who tend to live in beds, break up the tubs of these tanaids – and exclude the tanaids from that area. So now it’s a much safer place for little juvenile sand dollars to survive.”

For more news from Vancouver Island and beyond delivered daily into your inbox, please click here.

READ ALSO: Kings Park advocates call on Saanich to extend fundraising deadline, contribute $1.75 million to save greenspace


Do you have a story tip? Email: vnc.editorial@blackpress.ca.

Follow us on Twitter and Instagram, and like us on Facebook.

West Shore

Just Posted

Langley Lake supplies the drinking water for Union Bay. File photo by Bob Ell
Comox Valley board wants to halt Union Bay-area logging plans

Regional district inviting forest company to work on watershed plan

Corwin Fox performs on the grounds of the Courtenay and District Fish & Game Club for a 2021 Vancouver Island MusicFest segment, with the iconic Comox Glacier in the background. The 2021 festival will feature numerous outdoor segments, highlighting the beauty of the Comox Valley. Photo via Island MusicFest
2021 Vancouver Island MusicFest format will showcase the beauty of the Comox Valley

The 2021 Vancouver Island MusicFest -The Virtual Edition - will be like… Continue reading

Black Press file photo
RCMP seek suspect in Vancouver Island-wide crime spree

Crimes stretched from Deep Bay to Qualicum, Ladysmith, Chemainus and Youbou

Things are looking up for Vancouver Island as zero COVID-19 cases have been reported for the first time since October. THE CANADIAN PRESS/Darryl Dyck
Island records zero new COVID-19 cases for the first time since October

For the first time since October, the province is reporting zero new… Continue reading

Comox town hall. Black Press file photo
Comox takes step closer to finalizing Northeast Comox Storm Water Management Plan

“(This has been a) tremendous work in progress for many years”

John Marinus’s daughter, Margaret McCormack, and his wife Denise were out Saturday afternoon to help the Rotary Club of Comox move some tickets for the upcoming Ducky 500, known this year as the John Marinus Memorial Ducky 500. Photo by Mike Chouinard
Rotary Club of Comox Ducky Run tickets still available

Event has been rechristened as the John Marinus Memorial Ducky 500

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

Emily Steele holds up a collage of her son, 16-year-old Elijah-Iain Beauregard who was stabbed and killed in June 2019, outside of Kelowna Law Courts on June 18. (Aaron Hemens/Capital News)
Kelowna woman who fatally stabbed teen facing up to 1.5 years of jail time

Her jail sentence would be followed by an additional one to 1.5 years of supervision

Cpl. Scott MacLeod and Police Service Dog Jago. Jago was killed in the line of duty on Thursday, June 17. (RCMP)
Abbotsford police, RCMP grieve 4-year-old service dog killed in line of duty

Jago killed by armed suspect during ‘high-risk’ incident in Alberta

The George Road wildfire near Lytton, B.C., has grown to 250 hectares. (BC Wildfire Service)
B.C. drone sighting halts helicopters fighting 250 hectares of wildfire

‘If a drone collides with firefighting aircraft the consequences could be deadly,’ says BC Wildfire Service

A dose of the Pfizer-BioNTech COVID-19 vaccine is pictured at a vaccination site in Vancouver Thursday, March 11, 2021. THE CANADIAN PRESS/Jonathan Hayward
NACI advice to mix vaccines gets varied reaction from AstraZeneca double-dosers

NACI recommends an mRNA vaccine for all Canadians receiving a second dose of a COVID-19 vaccine

A aerial view shows the debris going into Quesnel Lake caused by a tailings pond breach near the town of Likely, B.C., Tuesday, Aug. 5, 2014. THE CANADIAN PRESS/Jonathan Hayward
Updated tailings code after Mount Polley an improvement: B.C. mines auditor

British Columbia’s chief auditor of mines has found changes to the province’s requirements for tailings storage facilities

A North Vancouver man was arrested Friday and three police officers were injured after a 10-person broke out at English Bay on June 19, 2021. (Youtube/Screen grab)
Man arrested, 3 police injured during 10-person brawl at Vancouver beach

The arrest was captured on video by bystanders, many of whom heckled the officers as they struggled with the handcuffed man

Most Read