Featured Research

from universities, journals, and other organizations

Urged on by urchins: How sea lilies got their get-up-and-go

Date:
April 17, 2010
Source:
University of Michigan
Summary:
Nature abounds with examples of evolutionary arms races. Certain marine snails, for example, evolved thick shells and spines to avoid be eaten, but crabs and fish foiled the snails by developing shell-crushing claws and jaws. Now, a study finds that sea urchins have been preying on marine animals known as crinoids for more than 200 million years and suggests that such interactions drove one type of crinoid -- the sea lily -- to develop the ability to escape by creeping along the ocean floor.

A sea lily, Endoxocrinus parrae, off Grand Bahama Island at a depth of about 1200 feet. The finger-like appendages of the stalk attach the animal to a boulder, and elevated arms form a circular filter oriented perpendicular to the current. The stalk is about 2 feet long.
Credit: Image courtesy of University of Michigan

Nature abounds with examples of evolutionary arms races. Certain marine snails, for example, evolved thick shells and spines to avoid be eaten, but crabs and fish foiled the snails by developing shell-crushing claws and jaws.

Related Articles


Common as such interactions may be, it's often difficult to trace their origins back in evolutionary time.

Now, a study by University of Michigan paleontologist Tomasz Baumiller and colleagues finds that sea urchins have been preying on marine animals known as crinoids for more than 200 million years and suggests that such interactions drove one type of crinoid -- the sea lily -- to develop the ability to escape by creeping along the ocean floor. The work, which builds on previous research on present-day sea lilies and urchins, is scheduled to be published online in the Proceedings of the National Academy of Sciences.

With their long stalks and feathery arms, sea lilies look a lot like their garden-variety namesakes. Perhaps because of that resemblance, scientists long had thought that sea lilies stayed rooted instead of moving around like their stalkless relatives, the feather stars. But in the 1980s, Baumiller and collaborator Charles Messing of Nova Southeastern University's Oceanographic Center in Dania Beach, Fla., observed sea lilies shedding the ends of their stalks to release themselves from their anchor points and using their feathery arms to crawl away, dragging their stalks behind them.

Then, while going through hundreds of hours of video shot during submersible dives, the two researchers came across footage that offered an explanation for why sea lilies might get up and go. The videos showed sea urchins lurking in gardens of sea lilies, some of which appeared to be creeping away from the predators. In some photos, the sea floor around the urchins was littered with sea lily arms, like table scraps left from a feast. Further studies by Baumiller, Messing and Rich Mooi of the California Academy of Sciences suggested that sea urchins don't simply scavenge bits of dead sea lilies that they find on the ocean floor; they bite pieces right off their prey, giving sea lilies plenty of reason to shed their stalk ends like lizards' tails and scoot away.

When those findings were announced in 2005, the researchers said the next step was to scrutinize fossil crinoids for clues to how and when sea lilies developed the ability to shed their stalk ends and move around. In the new research being reported in PNAS, that's what they, along with Forest Gahn of Brigham Young University and Polish collaborators Mariusz Salamon and Przemyslaw Gorzelak, have done.

First, the researchers put sea urchins into a tank with detached crinoid arms, pieces of crinoid stalks and arms, and live crinoids. Every urchin that was given the opportunity at least nibbled on crinoids, and one even ate a whole feather star. This experiment not only confirmed that urchins prey on crinoids, but it also revealed that crinoid parts that pass undigested through urchins bear characteristic scratches and pits that match the size and shape of the teeth in the urchin's "mouth."

To find out whether urchins preyed on crinoids in the distant past, the researchers looked for the same kinds of bite marks on more than 2,500 crinoid stalk fossils from Poland, dating back to the middle of the Triassic period, some 225 million years ago. More than 500 of the fossils had the telltale markings.

The findings suggest that the development of motility in crinoids, as well as other escape strategies such as active swimming and floating, were stimulated by their interactions with predators. The time frame is significant, too, said Baumiller, professor of geological sciences and a curator at the U-M Museum of Paleontology. Some of the best examples of the effects of escalating interactions between predators and prey come from something called the Mesozoic Marine Revolution (MMR), a dramatic increase in the diversity of predators and their prey that started during the late Mesozoic Era, about 150 million years ago. But the new study suggests that, at least for crinoids and their predators, the arms race began even earlier.

The research was funded by the National Science Foundation, National Geographic Society and the Foundation for Polish Science.


Story Source:

The above story is based on materials provided by University of Michigan. Note: Materials may be edited for content and length.


Journal Reference:

  1. Tomasz K. Baumiller, Mariusz A. Salamon, Przemys%u0142aw Gorzelak, Rich Mooi, Charles G. Messing, and Forest J. Gahn. Post-Paleozoic crinoid radiation in response to benthic predation preceded the Mesozoic marine revolution. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.0914199107

Cite This Page:

University of Michigan. "Urged on by urchins: How sea lilies got their get-up-and-go." ScienceDaily. ScienceDaily, 17 April 2010. <www.sciencedaily.com/releases/2010/03/100315172220.htm>.
University of Michigan. (2010, April 17). Urged on by urchins: How sea lilies got their get-up-and-go. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/2010/03/100315172220.htm
University of Michigan. "Urged on by urchins: How sea lilies got their get-up-and-go." ScienceDaily. www.sciencedaily.com/releases/2010/03/100315172220.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Researchers Test Colombian Village With High Alzheimer's Rates

Researchers Test Colombian Village With High Alzheimer's Rates

AFP (Dec. 19, 2014) In Yarumal, a village in N. Colombia, Alzheimer's has ravaged a disproportionately large number of families. A genetic "curse" that may pave the way for research on how to treat the disease that claims a new victim every four seconds. Duration: 02:42 Video provided by AFP
Powered by NewsLook.com
Monarch Butterflies Descend Upon Mexican Forest During Annual Migration

Monarch Butterflies Descend Upon Mexican Forest During Annual Migration

Reuters - Light News Video Online (Dec. 19, 2014) Millions of monarch butterflies begin to descend onto Mexico as part of their annual migration south. Rough Cut (no reporter narration) Video provided by Reuters
Powered by NewsLook.com
The Best Protein-Filled Foods to Energize You for the New Year

The Best Protein-Filled Foods to Energize You for the New Year

Buzz60 (Dec. 19, 2014) The new year is coming and nothing will energize you more for 2015 than protein-filled foods. Fitness and nutrition expert John Basedow (@JohnBasedow) gives his favorite high protein foods that will help you build muscle, lose fat and have endless energy. Video provided by Buzz60
Powered by NewsLook.com
Birds Might Be Better Meteorologists Than Us

Birds Might Be Better Meteorologists Than Us

Newsy (Dec. 19, 2014) A new study suggests a certain type of bird was able to sense a tornado outbreak that moved through the U.S. a day before it hit. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins