MAGNETIC ORIENTATION BY HATCHLING LOGGERHEAD SEA TURTLES

MAGNETIC ORIENTATION BY HATCHLING LOGGERHEAD SEA TURTLES

It is puzzling to think about how animals travel over vast distances even though they have never been there before. Humans use maps and gps's to travel. Animals on the other hand have to use other means to travel to places they have never been. One type of animal that travels far distances across the ocean are logger head sea turtles.

In an article by Kenneth J. Lohman, a professor in the Neural and behavioral biology department at the University of Illinois, he talks about the mechanisms that loggerhead turtles use to travel. The article suggests that the turtles are born with the innate ability to determine directional information from the earths magnetic fields. To study this researchers created a large man made tank. They put logger heads in the tank and manipulated different angles and intensities of magnetic fields similar to the fields found in nature. The researchers found that the different magnetic fields caused the turtles to travel in different directions.

Scientists believe that other migratory animals might use similar mechanisms to travel long distances. The physiological mechanisms the turtles use are still undetermined. The researchers think it has something to do with photo pigments that the turtles possess. This research has made it clear that animals us mechanisms that we still don't fully understand to migrate and orient themselves around the globe.

Posted by Charles Carville (sept.28)

Dancing Fly Stumps Evolutionists

Anyone familiar with animal behavior and evolution can tell you that animals do some pretty strange things to attract mates. According to sexual selection, the physical features, songs, or behaviors most attractive to females will become exaggerated in the males due to generations of selection for that trait. These traits or behaviors can range from typical (like the bright flashy plumage of a peacock) to weird (like the elaborate nest decorating done by male bowerbirds). But as always, they serve a distinct purpose: To advertise their superior size, strength, health, and overall ability to survive and provide relative to their competitors. However, a recent discovery of a bizarre sexually selected trait in Japanese dancing flies (family Empididae) is stumping scientists. In studying male dancing flies on Mt. Fuji, researchers discovered that many individuals have a modified fore tarsus on just one leg. This protrusion causes one leg to be oversized, and causes the fly to be asymmetrical. This in turn detracts the fly’s ability to fly efficiently. According to the authors of this study, such a massive polymorphic asymmetry occurring with so high an incidence in a population has never been discovered previously. The researchers in this study found so many cases of the asymmetrical male protrusions, that they ruled it out as a random freak of nature. Instead they hypothesize that the protrusion is a secondary sexual character meant to attract females. But why just the one? And is it worth the cost of flying well? The authors suggest that perhaps the male needs one leg to sit securely in one spot and wave his modified leg to attract females. Or, the oversized tarsus could contain a silk-secreting gland that can be used to catch and advertise a prey item to potential mates. But on the other hand, many males within the population had the protrusion on both legs, and others had none at all. More research must be done before any conclusions can be made, but what do you think? What would be the benefit of having one oversized leg and flying poorly, versus having two and flying ok, versus having none and flying well? And shouldn’t the females be attracted to males who can fly away quickly and avoid predators? I’m stumped.

-Jane de Verges
Fall 2010, Group A

Poop Munching Apes: Coprophagy

Most of us are quite familiar with the idea that apes are supposed to be our closest evolutionary relatives. We might marvel at how beautiful nature is when we witness an ape mastering the art of cracking a nutshell open with their fist just like humans do. On that note, we might find it quite shocking to witness apes eating their own “poop”. It is quite strange to see an ape eating their own poop, aren’t they supposed to be a very clever species after all?

Studies revealed that among the ape species, chimps and bonobos that are supposed to be our closest evolutionary relatives are the ones to eat their own feces. This type of behavior is called coprophagy where apes eat their own poop in order to retrieve hard, nutritious seeds from it. Copography is an adaptive behavior that apes have developed in order to survive during times when food is hard to find. The author of one of the studies witnessed an ape extracting seeds using their lips from the feces in their hand! The authors further suggested that coprophagy does not occur because of stress or boredom or simply as a habit. It is more common during times when food is hard to find.

It seems like the animal kingdom that does not always do beautiful things to impress us or grab our attention. Sometimes they do quite interesting things such as eat their own feces just for their own sake in order to survive. Similar studies have shown that, this behavior, called coprophagy is well known among rodents, rabbits and their relatives and less commonly among dogs and our closest relatives, apes.

Loba Alam