Copepods, a small type of plankton that drift in the sea, live close to the ocean’s surface where they are conspicuous targets for hungry fish below. But these little crustaceans have a surprising evasive maneuver: they jump out of the water and into the air to escape predators, according to a new paper in the Proceedings of the Royal Society B. Researchers at the University of Texas at Austin and colleagues used high-speed video recordings to track copepods, and found that those that break the water surface travel significantly farther than those attempting to escape underwater. This “flying” evasion helped copepods to more successfully evade predators.
Who would win a fight—a crocodile or Tyrannosaurus rex? According to a report in a recent issue of Biology Letters, the T. rex bit down with as much as 12,800 pounds of pressure on a single back tooth. That could easily take out a modern crocodile, the strongest biter among living animals, which has a bite force of 3,700 pounds. But the T. rex is no match for the largest extinct crocodilians, which generated bite forces in excess of 23,000 pounds, researchers from Florida State University reported last week (March 14) in PLoS One. This powerful chomp may be why crocodilians have remained kings of the water-land interface for over 85 million years.
Penguin victory dance
After a fight, territorial male blue penguins, Eudyptula minor, aren’t afraid to boast about their win. These little penguins perform a loud victory dance, waving their flippers and braying like donkeys. Scientists at the University of Waikato in Hamilton, New Zealand, wondered how all those victory displays affected nearby penguins, ScienceNOW reported.
Using fake eggs to measure the heart rate levels of brooding penguins in their burrows, the researchers found that both male and female penguins were stressed while listening to fight recordings. Additionally, males were more stressed if a winner approached their burrows, and were more likely to challenge an approaching loser. The research suggests that male blue penguins are signaling to bystanders not to mess with them.
Honeybee scouts may be little, but they are bold. Researchers at the University of Illinois at Urbana–Champaign investigated why some honeybees scout for food and new nesting sites while others stay cautiously at home. The team compared the gene expression profiles of the brains of adventurous honeybees to the brains of bees that stay close to the hive. They found that the scouting bees had dramatic gene expression differences in catecholamine, glutamate, and GABA signaling levels. Treating the scouts with glutamate increased their bold behavior, while blocking dopamine decreased it, according to the research published in Science.
The results raise the possibility that there's a genetic toolkit for this kind of novelty-seeking behavior in vertebrate species, including humans, author Gene Robinson told ScienceNOW.
Sawfish sense and impale prey
Sawfish are famous for their long toothy snouts, and now scientists have figured out what exactly what those saw-like snouts are used for. In the recent study in Current Biology, researchers at the University of Queensland report that the fish use their snouts both as a sensory organ and a hunting weapon. Filmed on hidden cameras, captured sawfish used their saws to tear into already dead fish. "I was surprised to see how skilled sawfish are with their saw," author Barbara Wueringer said in a press release. "They use their saw to impale prey on the rostral teeth by producing several lateral swipes per second."
The sawfish also used their snouts, which are covered with thousands of electroreceptors, to respond to weak electrical fields that mimicked live prey. But, the films revealed, sawfish do not use their snouts to rifle through the sand, as some related species do, BBC News reported.
Goats with accents?
Like humans, elephants, and dolphins, goats have the ability to modify the sound of their voice according to their social environments, according to a new study in Animal Behavior. Researchers at Queen Mary University of London studied the calls of four groups of pygmy goats, which live in complex social groups. They found that genetically related kids produced similar calls, which was not surprising, but the calls of kids raised in the same social groups were also similar to each other, and became more similar as the goats grew older.
“This suggests that goat kids modify their calls according their social surroundings, developing similar 'accents,'” co-author Elodie Briefer said in a press release. Vocal plasticity in goats could suggest a possible early pathway in the evolution of vocal communication, the authors noted.