Male fiddler crabs (Uca annulipes) grapple in fast, furious fights over ownership of burrows, and some of these territorial clashes may turn rivals into temporary allies.
Credit: Tanya Detto

This coprolite, or fossilized fecal matter (top), bears an array of tooth marks left by an ancient shark (mold of impressions at bottom; scale bar represents 1 centimeter).
Credit: Godfrey and Smith/Naturwissenschaften

Analyses suggest that the impressions were made as the shark bit its prey, as seen in this artist’s reconstruction.
Credit: T. Scheirer/Calvert Marine Museum

The first three-dimensional invisibility cloaks hide objects under stacked polymer rods.
Credit: Science/AAAS

A Samburu woman in Kenya, from a population of livestock herders, plays an experimental economics game while a research assistant watches.
Credit: Carolyn Lesorogol

An Au man, from a group of foragers and plant growers in Papua New Guinea, ponders how to divide money between himself and an anonymous partner.
Credit: David Tracer

Without the cloak (left), a bump in gold foil showed up clearly as a bright line in a spectral image taken in wavelengths just beyond the range of human vision. With the cloak (right), the bump disappeared.
Credit: Science/AAAS

A crustacean known as a Lyssianasid amphipod (orange blob at center) startled scientists who were peering at this camera feed from an underwater hole drilled through the Antarctic ice.
Credit: NASA

A close-up view of the very small resonator, taken with a scanning electron microscope, used in the first demonstration of quantum behavior in an everyday object. The resonator is made of a thin film of aluminum nitride sandwiched between aluminum layers. The mechanically active part of the structure is the quadrilateral shape in the center.
Credit: A. Cleland/UCSB

Setting the resonator to a high vibration cycle, illustrated in this cartoon that shows the expansion and contraction cycle that occurs 6 billion times a second, enabled researchers to coax the material into a quantum ground state using just a commercial-grade refrigerator.
Credit: A. Cleland/UCSB

The extrasolar planet COROT-9b is shown with its sunlike parent star in the background of this artist’s impression. The body is the first transiting planet cool enough to have a composition similar to Jupiter and Saturn, including a high layer of water clouds.
Credit: Instituto de Astrofísica de Canarias

The newly discovered extrasolar planet COROT-9B (shown as black dot) passes in front of its parent star in this drawing. The Jupiter-like planet orbits its star in 95 days at an average distance similar to Mercury’s average separation from the sun.
Credit: ESA

Erika DeBenedictis, 18, won first place in the Intel Science Talent Search for writing navigation software for spacecraft traveling an interplanetary superhighway. She presented her research at the National Academy of Sciences March 14.
Credit: Chris Ayers/Intel STS

An intricate network of lakes and rivers below Antarctica's ice sheet could be home to lots of microbes churning out the greenhouse gas methane.
Credit: Zina Deretsky/NSF

This portrait of Mars’ moon Phobos was taken by the Mars Express spacecraft on March 7. The craft flew 130 kilometers above the surface and resolved features as small as 4.4 meters. Full story
Credit: G. Neukum/FU Berlin, ESA, DLR