24 January 2014
African Tigerfish jump out of the water . . . into the air . . . and catch birds in flight. Tigerfish, in a storage lake for the Schroda Dam in South Africa, were caught, on video, grabbing barn swallows out of the air.
Sometimes called the “African piranha,” the tigerfish is a scary looking fish. [image] However, the tigerfish and piranha are two different species with the tigerfish winning contest as the bigger and meaner of the two. Like piranhas, tigerfish have “interlocking, razor-sharp teeth”, “are … extremely aggressive … predators”, and “often hunt in groups.” Both species have been known to attack humans. But unlike the relatively small piranha, an individual tigerfish weighs about 110 pounds.
The story of the tigerfish jumping out the water and grabbing birds, in flight, has been around since the 1940’s. But, for the first time, an “air-feeding” tigerfish has been caught on video.
Nico Smit, director of the Unit for Environmental Sciences and Management at North-West University in Potchefstroom, South Africa, was part of the team that caught the tigerfish feeding on birds. He said that the whole “event” happens so fast that it took a while before the researchers were sure what they were seeing.
It didn’t just happen fast. It happened often. They saw 20 “catches” the first day and about 300 during the next two weeks. The “event” was caught on video for the first time by team member Francois Jacobs. The team’s findings were published in the Journal of Fish Biology and Nature.com.
The tigerfish favors the twilight as the time of day for hunting birds in flight. This fish has two varied approaches to the hunt. Sometimes, the tiger will swim near the surface of the water following the birds, in flight, before jumping up into the air to make a catch. Other times, the fish will lurk in the deeper water tracking the birds. Then, it will leap out of the water and ambush a bird as it flies by.
Smit is amazed at the skill displayed by the fish in spotting and pacing the birds from the water. Not only does the fish have to estimate and exceed the birds’ speed, but the tiger has to compensate for the light refraction in water. This is quite a trick. The angle of the light changes when it passes from the air into the water. This makes estimating the location and speed of objects in the air a lot tougher.
This has been quite a year for videos catching aquatic animals feeding out of the water. First, Julien Cucherousset of Paul Sabatier University caught catfish on video in France’s River Tarn as they practiced their recently acquired skill of jumping out of the water to grab and eat pigeons wandering on shore. Then, an octopus was caught on video leaving the ocean for a stroll on a California beach in search of meal. And, now, a fish leaps into the air to catch birds — in flight!
Where will it end?
Maybe it hasn’t.
In another recent “photo first,” Jun Yamamoto of Hokkaido University and his team recorded squid leaping out of the ocean just off the coast of Japan. These “flying” squid travel almost 100 feet before reentering their water. Not only do these flyers extend their legs and gills, like wings, to stay airborne, but they actually flap their fins for some added “bird-like” lift.
You have to wonder (or worry) what’s going to be walking or flying out of the water next.
M Grossmann of Hazelwood, Missouri
& Belleville, Illinois
THURSDAY: How do the Bees Feel?
13 March 2014
Researchers are asking a lot of questions about animals lately. Are animals self-aware? Do they think? And these questions are reaching beyond animals to insects as well. Do bees have personalities? And, now, do bees have feelings?
It’s no surprise that this type of research tends to raise more questions than it answers. Tests seem to show that bumblebees have no individual personality. But even if bumblebees are conformists to a fault, could honeybees be non-conformists? And, even if honeybees don’t have individual personalities, could hives or even swarms of bees have distinct personalities? The idea of a group of bees having a personality seems “way out there” until you find out that beekeepers have always reported that, as a group, the bees of different hives, in many ways, behave quite differently from the bees of neighboring hives.
But the question of bees having feelings seems like a tough one to test. However, finding out whether or not bees become moody may not be as tough as we thought. It turns out that when human beings and animals are in bad moods, they tend to make negative judgments. In other words, we’re all a bit pessimistic when we’re in a bad mood.
But let’s begin at the beginning. One characteristic of feelings is that they change. If a person or animal always feels exactly the same way, they can’t really be said to have feelings. Now, let’s substitute the word “mood” for feeling. Why? Moods, by definition, change. So, the word “mood” is a little more precise than the word “feeling.”
Now, how can you tell if an insect has moods? Maybe, by using the same test that is used with animals.
The trick of the test involves negative judgments. Human beings and animals evaluate and react to situations differently when we’re in a good mood than when we’re in a bad mood. A good example is a decision based even odds – a coin toss. Would you bet on a toss of a coin? Your odds are exactly as good as they are bad.
I’ll guess that if you’re asked to bet money, but trying to be frugal, going through hard times, and are a bit short of cash, you’ll pass on the bet. On the other hand, if you’ve got plenty of money and have just had a few really good breaks, you might just take the bet. Why? Your mood. You’re feeling lucky.
So, for our test, we need four things. First, we need to find the equivalent of a coin toss for bees. Second, we have to offer the bet to the bees and see how many take the bet and how many refuse the bet. Third, we have to find a way to change the bees’ moods. And fourth, we have to offer those same bees the same bet, again, and see if their changed moods affects their willingness to take a chance..
As tough as all this sounds, Geraldine Wright and her colleagues at Newcastle University in the UK found a way.
Bees have an excellent sense of smell and are quickly and easily trained to associate particular smells with particular things. Wright’s team, headed by Melissa Bateson, first, found something honeybees love, surcose (sugar), and something bees hate, quinine. Then, they found two substances with very different smells, octanone and hexanol. The octanone was paired with the much loved sugar and the hexanol with the hated quinine. The bees were trained to associate the smells with the substances that they loved and hated.
Then, the researchers combined the chemical smells. When the well-trained bees were exposed to a combination of half octnone (lovable sugar) and half hexanol (hated quinine) half the bees “took a chance” and tasted what they hoped was sugar. The other half passed, not willing to risk licking the hated quinine.
The researchers had their “coin toss” – a choice with even odds. Now, that the bees’ reaction to the half and half solution was known, the next trick was to put the same bees in a bad mood. This isn’t as hard as it sounds because there are different types of bad moods. It wasn’t necessary to depress the bees by having them watch a sad movie. Substantial stress will produce a bad mood more surely than anything else.
Labs have chemical mixers mounted to benches. These mixers are machines that violently vibrate/shake containers to mix their contents. With the menacing name, vortexer, I get the impression that these machines are a bit like paint mixing machines at the local hardware store. Few could disagree that shaking a group of bees in a container in one of those mixers would leave the insects quite “stressed” – a very bad mood.
After a stay in the mixer, the bees were presented with the half and half solution again. Many more bees passed on the “chance” for sugar than had before. So, changing the bee’s mood, changed their “feelings” about taking a 50/50 chance to get some food. After the “mixing,” the bee’s weren’t so anxious to take the risk. This seems to indicate that bees have moods – feelings.
Of course, there are a lot of questions about the reliability of the results. Could the apparent “mood” be an automatic response based on hormonal changes or hard-wired neurological reactions? These researchers, however, expressed cautious confidence in their results. Also, the researchers made a surprisingly compelling argument that much of the doubt about the “feelings” of bees may be the result of a subtle prejudice.
The researchers pointed out that if, instead of bees, the subjects of the experiment had been dogs, cats, horses, parrots, cows, or pigs, the conclusion that the experimental subjects had feelings would have gone unquestioned. Why? Well, when testing animals with which human beings have had a close historical relationship, not only are results indicating emotion and intelligence readily accepted, but researchers are willing to make far reaching assumptions based on little more than their personal instincts about particular behaviors.
Jason Castro in his excellent article, Do Bees Have Feelings, refers to this argument as a plea for consistency. We often ascribe emotions to dogs, such as happiness, fear, or anxiety with little, or only intuitive, “evidence.” However, even strong evidence indicating that an insect has feelings is met with hairsplitting reservations.
The conventional wisdom has always been expressed as follows: Unless we discover a way to speak directly with animals, we can never be sure if animals experience emotions in the way that human beings do. However, whether I am in a good mood or a bad mood, I’m less pessimistic about finding the answer to the question of animal and, even, insect emotion. I think that there is a preponderance of evidence sufficient to accept the hypothesis that certain animals experience certain emotions. And, although more research is needed, these first tests, alone, strongly argue that insects, honeybees, experience moods.