How Sea Stars See

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 It sounds like the description of an alien in a sci-fi horror film. The creature moves around on tube feet, can regrow its arms, and disgorges its stomach
 
 into
 
 prey that’s larger than itself. Oh, and it has eyes on each of its many arms.
 

 Yet its not the fabrication of an overactive scriptwriter’s mind. It’s a sea star. We’ve known about many of sea stars’ remarkable traits for years, and scientists suspected that structures on the end of each arm functioned as eyes. But they didn’t know whether the eyes were of any use to the sea stars.
 
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 To test how sea stars may use that vision, Anders Garm and Dan-Eric Nilsson, of the University of Copenhagen and Lund University in Sweden, respectively, first examined the structures of blue sea stars (
 
 Linckia laevigata
 
 ) in detail, revealing a compound eye on each foot. Those eyes, however, are relatively crude. They don’t have lenses and can’t see in great detail.
 

 But Garn and Nilsson suspected that those simple images were enough to help the sea stars get around.
 

 Sarah Zielinski, writing for Science News:
 
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 So here comes the gruesome part: They went to a reef in Japan where the sea stars live and used a pair of scissors to cut off the eyes on five of them, along with a couple of tube feet and ossicles. And as a control, the scientists did a sham operation on five more starfish that removed tube feet and ossicles only. (This seems really mean, I know, but starfish can grow back whole arms, so it’s not quite as bad as it sounds.)
 

 After letting the animals heal overnight, the researchers placed the starfish about a meter away from a reef and watched as the sea stars began to move slowly. Nearly all of the sham-operated starfish made a beeline for the reef, but the eyeless sea stars just wandered. Similarly, intact starfish left a meter from the reef on a moonless night also failed to find their way home.
 
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 Clearly, there’s more to sea stars than meets the eye. Information about sea star vision not only contributes to our growing understanding of the evolution of sight—which has evolved on many different occasions—but it could also be helpful for future research into sea star ecology. Garm is already planning to apply this research with a different species, the crown-of-thorns sea star (
 
 Acanthaster planci
 
 ), which can have a devastating effect on coral reefs. By determining how the echinoderm finds a reef, he hopes to create traps that would capture the predators before they cause any lasting damage.
 
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 Photo credit:
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Where's All the Antimatter? New Anti-Atom Beam May Hold the Answer

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 When the universe burst into existence, according to the Big Bang theory, a colossal explosion released all the matter in the universe. But it also created antimatter, the mysterious doppelgänger of the stuff you and I can see. The British physicist Paul Dirac discovered antimatter in 1928; he asserted that every particle has an “antiparticle” with nearly identical properties, except for an opposite electric charge. When matter meets up with its antimatter counterpart, they obliterate each other in a flash of energy.
 
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<figcaption>Every component of the Antiproton Decelerator is essential to discovering the mysteries of antimatter.
 
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 But here’s the conundrum: the laws of physics also require that matter and antimatter be created in pairs. Accordingly, the Big Bang would have had to produce equal parts matter and antimatter—but that’s not what we see in the universe today. What puzzles scientists is why we have such an abundance of matter and an apparent dearth of its twin.
 

 That’s where a new antimatter beam built at CERN fits in. Experts at the research facility in Geneva, Switzerland want to use it to learn how this disparity happened and what it means.
 

 Scientists have been observing and manipulating antimatter for years. But they haven’t gotten a good look at it because what’s needed to keep the anti-atoms from smashing into regular atoms—a magnetic field—easily confounds the detectors. Measuring anti-particles inside a magnetic field requires carefully eliminating
 
 the effects
 
 of that field—not an easy task.
 

 To make it work, CERN scientists started with hydrogen, the simplest atom in existence. To make anti-hydrogen, they combined antiprotons with antielectrons using an Antiproton Decelerator. Then, unlike with previous experiments, they used the magnetic field not to contain the antimatter, but direct it away from the strongest magnetic distortion so the spectra, or electromagnetic radiation, could be more accurately measured.
 

 Lead scientist Yasunori Yamazaki in a statement for CERN:
 
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 Our results are very promising for high-precision studies of antihydrogen atoms, particularly the hyperfine structure, one of the two best known spectroscopic properties of hydrogen. Its measurement in antihydrogen will allow the most sensitive test of matter/antimatter symmetry.
 
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 Yamazaki and his team report producing a beam that consisted of at least 80 antihydrogen atoms stretching for 8.9 feet. It’s an unprecedented level of manipulation, one that physicists hope will help them better understand antimatter and, ultimately, the universe.
 

 This beam could be the foundation of a whole new world of new discoveries. The scientists can now begin to use this beam to perform experiments that test the properties of antimatter. With this ability to create such tangible antiatoms, and the current detail of knowledge that scientists know about the functions and properties of matter, our unanswered questions about the universe’s comparatively scarce antimatter are starting to have a foreseeable future.
 
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Scientists recently discovered the clymene dolphin is a hybrid species.

Hybrid Dolphin Gives Scientists Rare Window into Evolution

You’ve seen DNA analysis on every forensic criminology show on TV. Normally, it leads detectives to the killer, but in another case—this one on the open ocean—it has led scientists to a hybrid dolphin.


 The clymene dolphin (
 
 Stenella clymene
 
 ) is something of a biological riddle. Though these animals were first declared their own species by the American Society of Mammalogists in 1981, they were originally thought to be a subspecies of the spinner dolphin (
 
 S. longirostris
 
 ), despite their similarities to the striped dolphin (
 
 S. coeruleoalba
 
 ). DNA analysis has solved the puzzle, conclusively stating that clymene dolphins are a distinct species.

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 In her study, Ana Amaral at the University of Lisbon collected both mitochondrial and nuclear DNA from 72 individuals of the three similar dolphin species. Mitochondrial DNA is passed on through the organism’s mother, whereas nuclear DNA comes from both parents. Here, analyzing both was key. In her analysis, Amaral found that the DNA from the nucleus was most similar to the spinner dolphin, while DNA from the mitochondria was most similar to the striped dolphin.


 This suggests that the clymene dolphin is the product of crossbreeding striped and spinner dolphins—natural hybrid, something scientists know is rare but possible in wild animals. Hybrids are thought to be even rarer still in marine mammals, and before this study, hadn’t been previously documented. What’s more unusual was the fact that they produced not only viable offspring, but an entirely new species.


 Charles Q. Choi, writing for National Geographic News:

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 “You need to have hybrids be as fit as the parental species, able to carve out their own ecological space,” explained [evolutionary ecologist Pamela Willis of the University of Victoria in Canada].


 Then they somehow have to mate with only each other, rather than with either parental species, “hence allowing them to spin off onto their own, independent evolutionary trajectory and become a species of their own,” Willis added. “Both of these conditions are hard to meet.”

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 It’s a rare window into an evolutionary process that’s seldom seen in animals as advanced as cetaceans. Fortunately, we still have clymene dolphins around to witness it, though the situation for many dolphin species is increasingly dire.

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 Photo credit: NOAA

New study provides a rare window into the evolutionary process.

Zoe Shribman

Articles

How Sea Stars See

Where's All the Antimatter? New Anti-Atom Beam May Hold the Answer

Hybrid Dolphin Gives Scientists Rare Window into Evolution

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