April 28, 2011
"Instead of having a single pair of general-purpose eyes like most other animals, box jellyfish have several different types of eyes used for special purposes," Anders Garm of the University of Copenhagen explained. "This means that each individual eye type is dedicated to support only a limited number of behaviors."
Studying the box jellyfish species, Tripedalia cystophora, a tiny (one centimeter across) Caribbean mangrove-specialist, researchers found that four of the species' eyes serve a special purpose. These four eyes look up constantly and are able to see at least 8 meters and 180 degrees out of the water.
The researchers believe the specialized eyes are used to navigate the waters by peering up at the mangrove canopy. Why the canopy? According to the researchers the jellyfish is making sure it doesn't stray too far from its preferred, shaded habitat where it feeds on copepods. If it heads out from the mangroves into the lagoon it faces starvation.
By moving the box jellyfish in tanks, researchers found that once out of visual range of the mangroves—and staring only at the blue sky and sunlight—the jellyfish lost all orientation, swimming randomly.
"It is a surprise that a jellyfish—an animal normally considered to be lacking both brain and advanced behavior—is able to perform visually guided navigation, which is not a trivial behavioral task," said Garm. "This shows that the behavioral abilities of simple animals, like jellyfish, may be underestimated."
There are just under 40 species of known box jellyfish in the world, many of which are venomous. The Tripedalia cystophora has not been evaluated by the IUCN Red List and to date has not even received its own Wikipedia page.
Critically endangered capuchins make tools to gather termites
(03/10/2011) Less than 200 blond capuchins (Cebus falvius) survive in the highly-fragmented habitat of Brazil's Atlantic Forest. But this tiny group of monkeys, only rediscovered in 2006, is surprising scientists with its adept tool-using abilities. Displaying similar behavior to that which made the chimpanzees of Gombe famous worldwide, the blond capuchins modify sticks to gather termites from trees; however, according to the study published in Biology Letters the blond capuchins use two techniques never witnessed before: twisting the stick when inside the termite nest and tapping the nest before inserting the stick.
Birds experience 'empathy' for their hatchlings
(03/09/2011) A new study has uncovered what many chicken owners would say is evident: a mother hen experiences empathy for her hatchlings. Published in the Proceedings of the Royal Society B, the study found that mother hens show both physiological responses and changes in behaviors when their chicks are even mildly distressed.
Elephants cooperate as well as chimps
(03/07/2011) A new study proves that elephants understand how sometimes two is better than one. Working with Asian elephants (Elephas maximus) at the Thai Elephant Conservation Center, researchers reconstructed a classic cooperation test that was originally developed for chimpanzees. Subjects must pull on a rope to receive a reward, such as food, however—and here's the crux—the treat is only released if two subjects cooperate by pulling on two different ropes simultaneously. The paper published in Proceedings of the National Academy of Sciences found that elephants were as capable of cooperation as chimpanzees.