Smithsonian researchers report that the brains of tiny spiders may fill their body cavities and overflow into their legs. As part of research to understand how miniaturization affects brain size and behavior, researchers measured the central nervous systems of nine species of spiders, from rainforest giants to spiders smaller than the head of a pin. As the spiders get smaller, their brains get proportionally bigger, filling up more and more of their body cavities.

Scientists braved ticks and a tiger to discover how human activities have perturbed the nitrogen cycle in tropical forests. Studies at two remote Smithsonian Institution Global Earth Observatory sites in Panama and Thailand show the first evidence of long-term effects of nitrogen pollution in tropical trees.

Smithsonian scientists have discovered two new, closely related bee species: one from Coiba Island in Panama and another from northern Colombia. Both descended from of a group of stingless bees that originated in the Amazon and moved into Central America, the ancestors of Mayan honeybees.

History and geology, not current ecology, are likely what has made tropical forests so variable from site to site, according to a new study published in the journal Science, co-authored by Liza Comita, research associate at the Smithsonian Tropical Research Institute in Panama.

Smithsonian scientists and colleagues report that snails successfully crossed Central America, long considered an impenetrable barrier to marine organisms, twice in the past million years -- both times probably by flying across Mexico, stuck to the legs or riding on the bellies of shorebirds and introducing new genes that contribute to the marine biodiversity on each coast.

One toxic butterfly species may mimic the wing pattern of another toxic species in the area. By using the same signal, they send a stronger message: DON'T EAT US! Now several research teams that include Smithsonian scientists in Panama, have discovered that Heliconius butterflies mimic each other's red wing patterns through changes in the same gene.

An unusual signal detected by the seismic monitoring station at the Smithsonian Tropical Research Institute's research facility on Barro Colorado Island results from waves in Lake Gatun, the reservoir that forms the Panama Canal channel, scientists report. Understanding seismic background signals leads to improved earthquake and tsunami detection in the Caribbean region where 100 tsunamis have been reported in the past 500 years.