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

Pam Bottomley (executive director), right and Sandy Hurley (president) of the Parksville Downtown Business Association visit the PQB News/VI Free Daily studio. (Peter McCully photo)
PQBeat: Downtown Parksville gears up for post-pandemic bounce back

Podcast: Hurley, Bottomley chat about what’s ahead for the PDBA

(Black Press file photo)
RCMP: Air ambulance called to Whiskey Creek after crash involving 2 motorbikes

Both riders taken to hospital with serious injuries

(File photo)
Crime report: Crooks busy pilfering bikes throughout Parksville Qualicum Beach area

Thefts among 295 complaints Oceanside RCMP deal with in one-week period

The Arrowsmith Search and Rescue logo on the back of a service vehicle. (Mandy Moraes photo)
Parksville and Qualicum Beach provide letters of support for Arrowsmith Search and Rescue

ASAR asks for increase in funding, one-time capital grant and for RDN to buy out current facility

The proposed running track upgrade at Ballenas Secondary is now on course. (PQB News file photo)
RDN: Parksville track upgrade project gains some traction

Staff recommends board approve $204,000 funding

People watch a car burn during a riot following game 7 of the NHL Stanley Cup final in downtown Vancouver, B.C., in this June 15, 2011 photo. THE CANADIAN PRESS/Geoff Howe
10 years ago: Where were you during the 2011 Vancouver Stanley Cup Riots?

Smashed-in storefronts, looting, garbage can fires and overturned cars some of the damage remembered today

Annamie Paul, leader of the Green Party of Canada, speaks at a news conference on Parliament Hill in Ottawa, on June 10, 2021. THE CANADIAN PRESS/Justin Tang
Green Leader Annamie Paul facing no-confidence motion from party brass

move follows months of internal strife and the defection of MP Jenica Atwin to the Liberals

Tulips bloom in front of the Supreme Court of Canada in Ottawa, Thursday, May 10, 2018. Day two of a full week of scheduled hearings will be heard in Federal Court today on a case involving Indigenous children unnecessarily taken into foster care by what all parties call Canada’s “broken child welfare system.” THE CANADIAN PRESS/Sean Kilpatrick
AFN slams Ottawa for ‘heartless’ legal challenge of First Nations child compensation

2019 decision awarded $40,000 to each Indigenous child removed before 2006

Rick Ruppenthal of Saltair will host a 12-hour talk-a-thon Friday, June 18 over Facebook live. (Photo submitted)
Talk-a-thon to focus on men’s mental health issues

Island man spearheading a campaign to generate more conversation during fundraiser

Ivy was thrown out of a moving vehicle in Kelowna. Her tail was severely injured and will be amputated. (BC SPCA)
Kitten thrown from moving vehicle, needs help: Kelowna SPCA

The seven-week-old kitten had severe tail and femur injuries

The Canadian Anti-Fraud Centre estimates that less than five per cent of mass-marketing fraud is ever reported.
Tips to avoid scams targeting Vancouver Island seniors

In most cases, fraudsters impersonate an individual, business or agency seniors recognize and trust

Vancouver courthouse. (Photo: Tom Zytaruk)
Man loses bid to appeal conviction for 1999 rape at Abbotsford music festival

James Redden, 53, formerly of Nanaimo, was found guilty in 2019 following six-day trial

A health-care worker holds up a sign signalling she needs more COVID-19 vaccines at the ‘hockey hub’ mass vaccination facility at the CAA Centre during the COVID-19 pandemic in Brampton, Ont., on Friday, June 4, 2021. This NHL-sized hockey rink is one of CanadaÕs largest vaccination centres. THE CANADIAN PRESS/Nathan Denette
‘Vaxxed to the max’: Feds launch Ask an Expert campaign to encourage COVID shots

Survey shows that confidence in vaccines has risen this spring

Port Alberni court house (Alberni Valley News)
Inquest set into 2016 death of B.C. teen after a day spent in police custody

18-year-old Jocelyn George died of heart failure in hospital after spending time in jail cell

Most Read