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 this week 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.
More information:Tomasz Baumiller:
6eea9e58f14e3110VgnVCM1000003d01010aRCRD&vgnextfmt=defaultProceedings of the National Academy of Sciences:
Nancy Ross-Flanigan | EurekAlert!
Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care
Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses