A new study finds that when a ball appears to magically change size in front of their eyes, female dogs notice but males don’t. The researchers aren’t sure what’s behind the disparity, but experts say the finding supports the idea that—in some situations—male dogs trust their noses, whereas females trust their eyes.
photos { Eylül Aslan }
With the steep decline in populations of many animal species, scientists have warned that Earth is on the brink of a mass extinction like those that have occurred just five times during the past 540 million years.
Each of these “Big Five” saw three-quarters or more of all animal species go extinct. (…)
Biologists estimate that within the past 500 years, at least 80 mammal species have gone extinct–from a starting total of 5,570 species. The team’s estimate for the average extinction rate for mammals is less than two extinctions every million years, far lower than the current extinction rate for mammals. (…)
If currently threatened species–those officially classed as critically endangered, endangered, and vulnerable–actually went extinct, and that rate of extinction continued, the sixth mass extinction could arrive in as little as 3 to 22 centuries.
{ EurekAlert | Continue reading }
It has been estimated that the earth alone could accommodate twenty million times its present population, living at 120 per square meter in a 2000-story building covering the entire earth. It would take us 890 years, at our present rate of growth, to get to that point.
{ via EconLib | Continue reading }
painting { Eric Thor Sandberg }
Humpback whales have their own version of the hit single, according to a new study. At any given time within a population, male humpbacks all sing the same mating tune. But the pattern of the song changes over time, with the new and apparently catchy versions of the song spreading repeatedly across the ocean, almost always traveling from west to east. (…)
This is the first time that such broad-scale and population-wide cultural exchange has been documented in any species other than humans, she added.
In recent years several studies have suggested that women’s voices change at different times over the menstrual cycle, with the tone rising as ovulation approaches.
Now a study conducted by researchers at the West Texas A&M University in which women’s voices were subjected to computerized acoustical analysis contradicts those findings.
After assessing 175 samples provided by 35 study participants at various points throughout the menstrual cycles, the researchers say that changes in hormonal status have no significant impact on eight distinct voice parameters.
photo { Zev Jonas }
A study found that pigeons recognize a human face’s identity and emotional expression in much the same way as people do.
Pigeons were shown photographs of human faces that varied in the identity of the face, as well as in their emotional expression — such as a frown or a smile. In one experiment, pigeons, like humans, were found to perceive the similarity among faces sharing identity and emotion. In a second, key experiment, the pigeons’ task was to categorize the photographs according to only one of these dimensions and to ignore the other. The pigeons found it easier to ignore emotion when they recognized face identity than to ignore identity when they recognized face emotion.
images { 1 | 2. Shomei Tomatsu }
Why is aspirin toxic to cats?
One animal’s cure can be another animal’s poison. Take aspirin – it’s one of the most popular drugs on the market and we readily use it as a painkiller. But cats are extremely sensitive to aspirin, and even a single extra-strength pill can trigger a fatal overdose. Vets will sometimes prescribe aspirin to cats but only under very controlled doses.
The problem is that cats can’t break down the drug effectively. They take a long time to clear it from their bodies, so it’s easy for them to build up harmful concentrations. This defect is unusual – humans clearly don’t suffer from it, and neither do dogs. All cats, however, seem to share the same problem, from house tabbies to African lions.
{ Discover | Continue reading }
The term big cat – which is not a biological classification – is used informally to distinguish the larger felid species from smaller ones. One definition of “big cat” includes the four members of the genus Panthera: the tiger, lion, jaguar, and leopard. Members of this genus are the only cats able to roar. A more expansive definition of “big cat” also includes the cheetah, snow leopard, clouded leopard, and cougar.
A venomous Egyptian cobra went missing from New York’s Bronx Zoo, prompting the closure of the zoo’s reptile house until further notice. (…)
The Egyptian cobra is most commonly found in North Africa. Its venom is so deadly that it can kill a full-grown elephant in three hours — or a person in about 15 minutes, according to wildlife experts. The venom destroys nerve tissue and causes paralysis and death due to respiratory failure.
If you’re looking for the latest in home exercise equipment, you may want to consider a dog.
Several studies now show that dogs can be powerful motivators to get people moving. Not only are dog owners more likely to take regular walks, but new research shows that dog walkers are more active over all than people who don’t have dogs.
One study even found that older people are more likely to take regular walks if the walking companion is canine rather than human.
photo { Brandon Mitchell }
Jellyfish have traditionally been considered simple and primitive. When you gaze at one in an aquarium tank, it is not hard to see why.
Like its relatives the sea anemone and coral, the jellyfish looks like a no-frills animal. It has no head, no back or front, no left or right sides, no legs or fins. It has no heart. Its gut is a blind pouch rather than a tube, so its mouth must serve as its anus. Instead of a brain, it has a diffuse net of nerves.
A fish or a shrimp may move quickly in a determined swim; a jellyfish pulses lazily along.
But new research has made scientists realize that they have underestimated the jellyfish and its relatives - known collectively as cnidarians (pronounced nih-DEHR-ee-uns). Beneath their seemingly simple exterior lies a remarkably sophisticated collection of genes, including many that give rise to humans’ complex anatomy.
These discoveries have inspired new theories about how animals evolved 600 million years ago. The findings have also attracted scientists to cnidarians as a model to understand the human body.
“The big surprise is that cnidarians are much more complex genetically than anyone would have guessed,” said Dr. Kevin J. Peterson, a biologist at Dartmouth. “This data have made a lot of people step back and realize that a lot of what they had thought about cnidarians was all wrong.”
Renaissance scholars considered them plants. Eighteenth-century naturalists grudgingly granted them admittance into the animal kingdom, but only just. They classified cnidarians as “zoophytes,” somewhere between animal and plant.
It was not until the 19th century that naturalists began to understand how cnidarians developed from fertilized eggs, their body parts growing from two primordial layers of tissue, the endoderm and ectoderm.
Other animals, including humans and insects, have a third layer of embryonic tissue, the mesoderm, wedged between the ectoderm and the endoderm. It gives rise to muscles, the heart and other organs not found in cnidarians.
Cnidarians also have a simpler overall body plan. Fish, fruit flies and earthworms all have heads and tails, backs and fronts, and left and right sides. Scientists refer to animals, including humans, with this two-sided symmetry as bilaterians. In contrast, cnidarians seem to lack such symmetry completely. A jellyfish, for example, has the symmetry of a bicycle wheel, radiating from a central axis.
print { Constance Jacobson }
{ We’re in Siberia, shivering. It’s November, November 11, 2003, and two boys, Kolya and Maksim Muravyev, are ice fishing along the Lena River, where it’s 13 below zero. All of a sudden, up in the sky, they see what looks like a flamingo. | NPR | Continue reading }
{ Our results show that dog and cat owners use these sites quite differently. While dog owners focus on their relationship with their pets and looking for advice, cat owners tend to use the site more to build community. Both results show that these pet social networks are already being used to help support the human–animal bond online. | First Monday | full story }
Shanghai is to extend the one-child policy to man’s best friend after tens of thousands of people complained of being bitten last year – and to prevent dog mess spoiling the country’s showcase business city.
The rule has already been imposed in several other Chinese cities, but Shanghai’s size – it has a population of more than 20 million – has made the presence of thousands of dogs more problematic. Dogs bigger than 3ft will be banned from the centre of the city and so-called “attack dogs”, including bulldogs, will be banned completely.
The ruling is the latest instance of uneasy relationships between man’s best friend and the Chinese authorities. During the Communist era of Mao Zedong, pets were frowned upon as a middle-class affectation and government opponents were condemned as capitalist running dogs. But China’s growing openness, combined with its rising affluence, means that pets are making a comeback, and there are around 100 million pet dogs in China. However, from May, a one-dog policy will be introduced in Shanghai and more than 600,000 unlicensed dogs will be declared illegal – and killed because of fears of rabies.
photo { Alvaro Sanchez-Montañes }
related { The special bond that often forms between people and both domesticated and wild animals may be, paradoxically, part of what makes us human. | Seed | full story }
{ In 1900, a German named Wilhelm von Osten displayed to the public his horse, Clever Hans (Kluge Hans), who was apparently able to perform mathematical calculations. | Encyclopedia of Claims, Frauds, and Hoaxes of the Occult and Supernatural | Continue reading }
This paper investigates the relationship between environment and behaviour in a butterfly.
Adult butterflies are highly visual animals, relying on their keen eyesight to locate and identify appropriate mates by looking at and comparing their wing colours and patterns. Many butterflies show variations in wing colours and patterns depending upon the season they experienced as caterpillars or whilst cocooning. Knowing this, it is reasonable to assume that differences in wing colours and patterns (known as polyphenisms) could affect how adult butterflies interact with each other. But do wing polyphenisms affect adult butterfly behaviours? If so, how?
Dr Katy Prudic, and her postdoctoral advisor, Dr Antónia Monteiro, researchers in the Department of Ecology & Evolutionary Biology at Yale University, investigated the relationship between the environment and behaviour in the east African butterfly species, the squinting bush brown butterfly, Bicyclus anynana.
Even though this butterfly species has been bred and raised in captivity for 30 years, Dr Prudic was the first person to notice that female B. anynana appeared to be colour-coded according to season. When the adult butterfly holds its wings closed, as when perched on a flower, the exposed dorsal wing surfaces show distinct seasonal differences: adult butterflies that experienced a wet warm season as caterpillars have brighter and more numerous eyespots (figure 1A) than those seen in the cooler dry season form (figure 1B):
