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

Two ambulances and a medevac helicopter are on scene at Taylor River Flats rest area on Highway 4 due to a serious motor vehicle incident. (PHOTO COURTESY MAGGIE BROWN)
Highway 4 reopens after accident at Taylor River Flats

Multi-vehicle crash had closed highway to west coast

Grade 12 graduates Jada Touchie, Timothy Masso and Brendan Brown are all smiles after receiving their Goodies for the Grads gift packs thanks to a small neighbourhood grant from the Clayoquot Biosphere Trust. (Nora O’Malley photo)
Ucluelet Secondary School grads set to parade through town

Family and friends can cheer on the Class of 2021 this Saturday, June 19 at 4:30 p.m.

From left, Ahousaht First Nation Hereditary Chief Richard George presents a $10,000 cheque to Tofino Hatchery manager Doug Palfrey alongside Tyler Huebner of TCH Contracting The funds will go towards rebuilding Cypre river Chinook. (Carallyn Bowes photo)
Tofino Hatchery receives $10K donation

Tofino Salmon Enhancement Society tackling massive drop in Chinook salmon stocks

Creative handmade signs abound at the June 13 Tofino rally for old growth trees. (Nora O’Malley photo)
VIDEO: Tofino stands in solidarity for Fairy Creek Blockades

Over 150 supporters attend rally hosted by Friends of Clayoquot Sound

This rendering shows the potential layout for a 40-unit staff housing cooperative being proposed by the Pac Rim Home Development Cooperative in Ucluelet. (Image from www.prhdc.ca)
Pac Rim Cooperative pitches staff housing project in Ucluelet

“We’re looking at it as if it’s like a resort for employees”

Maxwell Johnson is seen in Bella Bella, B.C., in an undated photo. The Indigenous man from British Columbia has filed complaints with the B.C. Human Rights Tribunal and the Canadian Human Rights Commission after he and his granddaughter were handcuffed when they tried to open a bank account. THE CANADIAN PRESS/HO-Heiltsuk Nation, Damien Gillis, *MANDATORY CREDIT*
VIDEO: Chiefs join human rights case of Indigenous man handcuffed by police in B.C. bank

Maxwell Johnson said he wants change, not just words, from Vancouver police

Tk’emlups te Secwepemc Chief Rosanne Casimir stands outside the former Kamloops Indian Residential School after speaking to reporters, in Kamloops, B.C., on Friday, June 4, 2021.THE CANADIAN PRESS/Darryl Dyck
Kamloops chief says more unmarked graves will be found across Canada

Chief Rosanne Casimir told a virtual news conference the nation expects to release a report at the end of June

A woman wears a vaccinated sticker after receiving a COVID-19 vaccine at a vaccination clinic run by Vancouver Coastal Health, in Richmond, B.C., Saturday, April 10, 2021. THE CANADIAN PRESS/Jonathan Hayward
B.C. ranks among highest in world in COVID-19 first-dose shots: health officials

More than 76% of eligible people have received their 1st shot

A screenshot of the First Peoples Cultural Councils First Peoples’ Map. (First Peoples Cultural Council)
Online resource blends B.C.-Alberta’s Indigenous languages, art and culture

Advisor says initiative supports the urgent need to preserve Indigenous languages

An artists conception of the new terminal building at the Pitt Meadows Regional Airport.
Air travel taking off in B.C., but lack of traffic controllers a sky-high concern

There will be demand for more air traffic controllers: Miller

Canadian Armed Forces experts are on their way to North Vancouver after a local homeowner expressed worry about a military artifact he recently purchased. (Twitter DNV Fire and Rescue)
Military called in to deal with antique ‘shell’ at North Vancouver home

‘The person somehow purchased a bombshell innocently believing it was an out-of-commission military artifact’

Amy Kobelt and Tony Cruz have set their wedding date for February, hoping that more COVID-19 restrictions will have lifted. (The Macleans)
B.C. couples ‘gambling’ on whether COVID rules will let them dance at their wedding

Amy Kobelt and Tony Cruz pushed back their wedding in hopes of being able to celebrate it without the constraints of COVID-19

A plane is silhouetted as it takes off from Vancouver International Airport in Richmond, B.C., May 13, 2019. THE CANADIAN PRESS/Jonathan Hayward
Report calls for airlines to refund passengers for flights halted due to COVID-19

Conclusion: federal help should be on the condition airlines immediately refund Canadian travellers

Green party Leader Annamie Paul speaks during a news conference on Parliament Hill in Ottawa on Tuesday, June 15, 2021. Paul has survived another day of party strife after a planned ouster shifted course, leaving her with a tenuous grip on power ahead of a likely federal election this year. THE CANADIAN PRESS/Justin Tang
Green Leader Annamie Paul blasts ‘racist,’ ‘sexist’ party execs who sought ouster

Fallout has continued, with two of the federal council’s members resigning

Most Read