Feeding your snake too much may starve it to death

By: Terry Jester

“How refreshing to finally get a call about a snake problem.

When Brian of Fort Collins contacted me recently about his ball python refusing to eat, I was more than happy to help.

Gerta, his python, was 3 feet long and lived in a 20-gallon reptile container. She was tolerant of people handling her and had been eating regularly until a few months ago.

The veterinarian couldn’t find anything wrong with the python, but she hadn’t eaten in six weeks and Brian was worried about her. Could I help him, he asked?

I asked Brian how often and how much the snake had been eating prior to her refusing food. He said that she normally ate two or three mice, depending on the size, once a week. Then I asked Brian what kind of exercise the snake usually received.

Brian was bewildered about the exercise question. He replied that she didn’t get any exercise because she lives in a container.

That is your problem, I told him. Snakes have to hunt for their food in the wild. Rarely does food wander up and climb into the snake’s mouth. The snake has to go find it.

Snakes have many muscles. The muscles help propel the snake across the ground, but they also help it digest its food. Snakes can digest food without much exercise, but it’s easier for them to digest if they are moving around a little.

Extremely lethargic, captive snakes being over-fed have a hard time digesting their food. They are full, so they don’t feel the need to move around. The food just sits there clogging up the system.

Eventually, everything sort of shuts down. Some switch in the snake’s brain flips and the snake no longer feels hunger.

I told Brian he needed to get Gerta out of the tank every day and get her exercising. The best exercise would be to have her swimming in warm water for a few minutes every day. This exercises all the muscles in her body and will help her system get back into a regular rhythm.

Once the feeding problem is gone, getting her out for a swim or a handling session at least twice a week is recommended.

When the hunger switch flips back on, I told him not to over-feed her. One large mouse or two small mice every week to 10 days is adequate for a 3-foot captive python. If she starts moving around a little bit in between feedings, that means her body is working as it should. Feed her more or more often only if she isn’t keeping her weight up.

After two weeks, Brian called and said his snake was back to eating. Gerta seems to enjoy her baths, and everyone except the mice are happy.”

From coloradoan.com

Ultrasonic frogs can tune their ears to different frequencies

Researchers have discovered that a frog that lives near noisy springs in central China can tune its ears to different sound frequencies, much like the tuner on a radio can shift from one frequency to another. It is the only known example of an animal that can actively select what frequencies it hears, the researchers say.

The findings, from a collaborative effort led by the University of Illinois and the University of California at Los Angeles, appear this week in Proceedings of the National Academy of Sciences. The research team also included scientists from the Chinese Academy of Sciences and the Massachusetts Eye and Ear Infirmary (at Harvard Medical School).

The discovery was made when researchers examined the eardrums of an unusual frog, Odorrana tormota, which communicates by making birdlike calls in the audible and ultrasonic frequency ranges. Previous research by two of the authors showed that the frog produces and responds to ultrasonic calls. In the new study they sought to determine whether the frog’s eardrums actually vibrate in response to these ultra high frequency sounds.

Using a laser vibrometer to measure the eardrum’s vibration, the researchers found that the eardrum did respond to sounds in the sonic and ultrasonic ranges. But they also saw something they couldn’t explain: The eardrum’s sensitivity to ultrasound sometimes disappeared altogether.

Normally sound waves strike the eardrum and – if they are powerful enough and in a frequency range that the animal can perceive – cause the eardrum to vibrate. In most studies of frogs, the eardrum responds exactly the same way to the same sound stimulus. Even the eardrums of a dead frog will respond with unchanging predictability.

Past research showed that a frog’s eardrum never responds differently to the same sound stimulus, said team leader Albert Feng, a professor of molecular and integrative physiology at Illinois.

“This was contrary to everything that we knew about its auditory system,” he said.

O. tormota, the concave-eared torrent frog, is unusual in other ways. Most frogs have ears on the body surface, but the torrent frog’s ears are recessed. Feng and his colleagues previously reported that O. tormota communicates in a noisy environment by emitting high frequency calls that include ultrasonic sounds, and can localize sound with astonishing precision. Upon hearing a female call, a male will leap directly toward the sound with an error of less than 1 percent, a feat previously unheard of in frogs.

Fortunately for the researchers, the eardrum of O. tormota is transparent, offering a view of its inner workings in a living frog.

While puzzling over the peculiar results of the eardrum vibration measurements, the researchers noticed the sudden appearance and disappearance of a dark shadow on the eardrum, Feng said.

Further investigation revealed that the frogs were actively opening and closing their Eustachian tubes, the two narrow channels that connect either side of the pharynx to the left and right middle ear. The changing state of the Eustachian tubes was more readily observed by directing a light beam at the mouth from under the frog’s chin. When the Eustachian tubes were open, the light was visible through the eardrum. When they closed, the circles of light glowing out through the ears disappeared. (Movie available.)

“We said, ‘Whoa! This is bizarre!’ ” Feng recalled. “In all textbooks on sound communication and hearing in frogs, it is plainly stated that the Eustachian tubes are permanently open!”

Feng and his colleagues had observed that when open, the Eustachian tubes essentially couple the frog’s left and right ears. This “acoustic coupling” between the ears makes them sensitive to sound direction, enabling the frog to localize sound, Feng said.

To determine the consequence of active closure of the Eustachian tubes, the researchers measured how the open and closed Eustachian tubes affected the vibration of the eardrum.

They found that the frogs’ eardrums became very sensitive to high frequency and ultrasounds when their Eustachian tubes were closed, compared with when they were open. When the Eustachian tubes were open, the eardrums responded mostly to low frequency sounds.

The frogs appear to be able to tune in to specific sound frequencies at will, Feng said. They can shift to high frequency and ultrasonic hearing when the low frequency background noise of rushing water is too intense for them to pick out the calls of potential mates or rivals, he said.

This research likely has implications for human health. Earlier research into the mechanics of frog hearing helped Feng and his colleagues at the U. of I.’s Beckman Institute for Advanced Science and Technology design an “intelligent hearing aid” that boosts sound signals of interest.

From Innovations Report

Human-frog hybrids reveal autism’s secrets

Human-frog hybrids might reveal the neurological secrets of autism. By fusing cells from the preserved brains of deceased autistic patients with the eggs of a carnivorous African frog called Xenopus, scientists have started investigating the way the brain cells of people with autism behave.

The frog eggs work a little like human neurons and the hybrid cells act as a surrogate of a living brain with the condition.

“It’s almost as if you were studying a neuron in the human brain,” says Ricardo Miledi, a neurobiologist at the University of California, Irvine, who developed the approach and has previously used Xenopus eggs to study epilepsy.

Miledi’s earlier work has suggested that some brain cells of epilepsy patients have trouble sensing a molecule that helps damp down neuron activity. The proteins in question, called neurotransmitter receptors, sense the chemicals that neurons use to communicate, and Miledi thinks that problems with these proteins underlie epilepsy and other disorders

Some researchers blame autism on a malfunction in mirror neurons, cells that play a vital role in understanding the actions of others people.

To see if abnormalities in neurotransmitter signalling also underlie autism, Miledi’s team collected brain samples from six deceased autistic patients, aged eight to 39. They fused brain-cell membranes, which house neurotransmitter receptors, together with Xenopus egg membranes. As a control, they did the same thing with brain cells from patients with no history of mental disorder.

Miledi’s team then doused the frog eggs in neurotransmitter chemicals, and measured the voltage generated within each egg. The neurotransmitter chemicals tell brain cells to pump charged molecules in and out the membrane, creating a voltage across the membrane. Since Xenopus eggs do not respond to the neurotransmitters, the human proteins are completely responsible for any electric current generated.

Four of six autistic brains responded to neurotransmitters chemicals less vigorously than the controls.

However, Miledi cautions that more research with additional samples will be needed to firm up any conclusions. “Autism spectrum disorder is a very broad range of maladies, with many different sources and many different problems,” he says.

Jonathan Pevsner, a neurobiologist at Kennedy-Krieger Institute in Baltimore, Maryland, agrees that frog eggs could be useful for studying certain properties of autism, and perhaps uncovering new treatments.

He notes that other brain illnesses, such as depression and Parkinson’s, can be treated by turning the activity of neurotransmitters up or down. Hybrid frog eggs could perhaps hint at which neurotransmitters to tweak, he says.

Journal reference: PNAS (DOI: 10.1073/pnas.0804386105)

From New Scientist