Sunday, May 3, 2015
YOLO COUNTY NEWS
99 CENTS

Study: Turbulence tells sea urchins to settle in

Microscopic purple sea urchin larvae drift in the upper levels of the ocean for about a month before settling on a rocky shore and transforming into the familiar spiny adult. Researchers at UC Davis' Bodega Marine Laboratory have found that ocean turbulence plays a key role in the larvae's life cycle. Jason Hodin, Stanford University Hopkins Marine Station/Courtesy photo

By
From page A6 | April 18, 2013 |

Tumbling in the waves as they hit a rocky shore tells purple sea urchin larvae it’s time to settle down and look for a spot to grow into an adult, researchers at UC Davis’ Bodega Marine Laboratory have found.

“How these animals find their way to the right habitat is a fascinating problem,” said Brian Gaylord, a professor of evolution and ecology. “The turbulence response allows them to tell that they’re in the right neighborhood.”

Like most shoreline animals, purple sea urchins have a two-stage life cycle. The young are microscopic, look completely different from adults and drift in the upper levels of the ocean for about a month before settling on a rocky shore and transforming into the familiar spiny adult.

“Once they decide to settle, they attach to a rock and undergo body remodeling into a juvenile sea urchin with spines,” Gaylord said.

Over short distances, the larvae can respond to chemical traces in the water, especially substances that might be given off from a rock thick with algae or other food for the growing urchins.

But how do the larvae know they are close enough to the right shoreline habitat to start searching for such signals?

On the California coast, rocky headlands — the urchins’ preferred environment — are interspersed with long stretches of beach that experience lower levels of turbulence. The larvae don’t have the resources to swim for miles along a beach looking for a nice slimy rock, but when carried by currents near a wave-swept rocky reef, the high turbulence tells them to begin a finer-scale search, the researchers found.

Gaylord and co-authors Jason Hodin of Stanford University’s Hopkins Marine Station and Matthew Ferner of San Francisco State University used a device called a Taylor-Couette cell to see how urchin larvae responded to being churned by shear forces comparable to those in waves breaking on a rocky shore.

The Taylor-Couette cell consists of one rotating cylinder inside another, with a layer of fluid in between. When the cylinders spin relative to each other, they set up shear forces in the fluid. Scientists more typically use the device for studying fluid dynamics, especially the transition where flows becomes chaotic and turbulence appears.

Gaylord and his colleagues took the urchin larvae for a spin through a Taylor-Couette cell then exposed them to potassium, known to act as a chemical signal that triggers larvae to begin settling.

Larvae that had been exposed to turbulence responded to the chemical signal earlier in development than those that had not — in fact, they responded at a stage at which it had previously been believed larvae could not settle.

Especially telling was that neither turbulence nor the chemical signal alone promoted settling at this earlier developmental stage.

The experiment shows that the shift from living free in the ocean to living on a rock is a two-step process, Gaylord said. In the first step, exposure to turbulence initiates an abrupt transition to a state in which the larvae are “competent to settle.” A chemical signal triggers the second step, actual settlement, and the larvae then complete their transformation into juvenile sea urchins.

It’s not yet clear how the larvae detect turbulence, Gaylord said. That might happen through receptors that respond to stretching or flexing. The two-step settlement process might occur in other species that settle on shorelines, he said.

The work appears in the journal Proceedings of the National Academy of Sciences.

— UC Davis News Service

Comments

comments

.

News

Breaking barriers: For Prieto, it’s all about hard work

By Lauren Keene | From Page: A1 | Gallery

 
Council to hear about drought pricing

By Dave Ryan | From Page: A1

 
For the record

By Enterprise staff | From Page: A2

 
Peaceful Baltimore demonstrators praise top prosecutor

By The Associated Press | From Page: A2

Nigeria: Nearly 300 freed women, children led to safety

By The Associated Press | From Page: A2

 
Graveyard thefts land three Woodlanders behind bars

By Lauren Keene | From Page: A3

Downtown altercation leads to injuries

By Anne Ternus-Bellamy | From Page: A3

 
Woman arrested for brandishing knife on overpass

By Anne Ternus-Bellamy | From Page: A3

Yolo DA launches monthly newsletter

By Enterprise staff | From Page: A3

 
Can plants talk? UCD prof will answer that question

By Special to The Enterprise | From Page: A3 | Gallery

A Scottish setting for local author’s next book

By Special to The Enterprise | From Page: A3

 
Indoor Fun Fly comes to Woodland

By Enterprise staff | From Page: A4

 
Free beginner yoga class offered

By Enterprise staff | From Page: A4

Video discusses surveillance of prostate cancer

By Special to The Enterprise | From Page: A4

 
NAMI support group meets May 10

By Enterprise staff | From Page: A4

Dr. G featured on the radio

By Special to The Enterprise | From Page: A4

 
Fee proposed on rail cars that haul oil, other flammables

By The Associated Press | From Page: A4 | Gallery

 
Internships move UCD doctoral students beyond academia

By Julia Ann Easley | From Page: A5 | Gallery

Make Mom a warm vanilla sugar scrub

By Enterprise staff | From Page: A6

 
The secret to Mother’s Day gifting success: Give time, not stuff

By Special to The Enterprise | From Page: A6

Letter book is series of collected missives thanking Mom

By The Associated Press | From Page: A7

 
If your mom fancies something fancy, consider a tea party

By The Associated Press | From Page: A7

Out of Africa and back to Davis: James Carey will give special presentation

By Kathy Keatley Garvey | From Page: A9 | Gallery

 
Big Day of Giving makes philanthropy easy

By Tanya Perez | From Page: A10 | Gallery

Tuleyome Tales: How are a snake and a mushroom alike?

By Special to The Enterprise | From Page: A12 | Gallery

 
Tuleyome hosts Snow Mountain camping trip

By Special to The Enterprise | From Page: A12 | Gallery

.

Forum

Please help Baltimore

By Letters to the Editor | From Page: B4

 
End of life doesn’t mean life must end

By Special to The Enterprise | From Page: B4 | Gallery

Advancing education for California’s former foster youths

By Special to The Enterprise | From Page: B4

 
With sincere gratitude

By Letters to the Editor | From Page: B4

A wonderful day of service

By Letters to the Editor | From Page: B4

 
Eyewitness to the ‘fall’ of Vietnam: It was not a bloodbath

By Special to The Enterprise | From Page: B5 | Gallery

He can’t give it up

By Creators Syndicate | From Page: B6

 
 
Dangers from prescription pills

By Special to The Enterprise | From Page: B6

.

Sports

 
Defending champ DHS clinches a baseball playoff berth

By Enterprise staff | From Page: B1

UCD softball splits with Titans

By Enterprise staff | From Page: B1 | Gallery

 
Trifecta of Devil teams open playoffs Tuesday

By Evan Ream | From Page: B1 | Gallery

Sports briefs: DHS boys win to reach lacrosse playoffs

By Enterprise staff | From Page: B3 | Gallery

 
Making memories at Aggie Stadium

By Wayne Tilcock | From Page: B3 | Gallery

Pro baseball roundup: Hudson pitches Giants past Angels

By The Associated Press | From Page: B12

 
UCD roundup: Aggie women speed past Hornets

By Enterprise staff | From Page: B12 | Gallery

.

Features

.

Arts

.

Business

Marrone opens new greenhouse

By Special to The Enterprise | From Page: A8

 
New firm helps students on path to college

By Wendy Weitzel | From Page: A8

 
Yolo County real estate sales

By Zoe Juanitas | From Page: A8

Arcadia partners on soybean trait to improve yield

By Special to The Enterprise | From Page: A8

 
.

Obituaries

.

Comics

Comics: Sunday, May 3, 2015

By Creator | From Page: B8