Stories tagged frogs

Jul
26
2006

Maria McNamara of University College Dublin, and colleagues in the UK, Spain, and US, have recovered bone marrow from 10-million-year-old fossilized bones of frogs and salamanders found in Spain.

The marrow was preserved in 3D, and still has its original texture and color. Scientists think they may be able to extract traces of protein and DNA.

Even more interestingly, the fossils prove that ancient salamanders produced blood cells in their bone marrow. Modern salamanders, on the other hand, produce blood cells in their spleens.

Last year, US scientists recovered some tissue resembling blood vessels from a 65-million-year-old Tyrannosaurus rex fossil. They also found traces of what appeared to be red blood cells. (More on the T. rex find.)

And now that they're looking, scientists think they may find examples of preserved bone marrow in many fossils, raising the possibility of analyzing the proteins and DNA of lots of long-extinct organisms.

Feb
12
2006

It's a pretty amazing world we live in. Dozens of new species are discovered within days of more nearing extinction. I've heard it many times, and it seems almost corny to repeat it, but it has to be true that species have become extinct due habitat destruction, invasive species and who knows what else that we didn't even know existed.


Female mountain yellow-legged frog: Image courtesy U.S. Fish and Wildlife Service.

An example of one "what else" is the story of what's happening to the mountain yellow-legged frog. This little fellow would seem to be quite the survivor, living up to nine months under snow and ice in the Sierra Nevada range. The populations of these frogs were at one time so great that they were practically a tripping hazard. However this frog is headed towards extinction, fast.

But interestingly, it's not entirely our fault. Introducing trout to the lakes that the frogs had called home for sport fishing and forcing them into smaller more isolated lakes has not helped matters, nor has agricultural pollutants transported to the area by prevailing winds, but it turns out the biggest culprit is a fungus.

The chytrid fungus has caused frog extinctions in other countries, and grows on the skin of the frog, making it hard for them to properly use their pores to control their water intake — they die of thirst while they are living in water. And it is not just the mountain yellow-legged frog that is dying from this fungus, the boreal toad population in Rocky Mountain National Park is also being decimated by this fungus.

And because it is a fungus, not people that are pushing the frogs to extinction, the U.S. Fish and Wildlife Service is struggling to declare the frog an endangered species. Since the fungus is natural and not the by-product of agricultural waste or pollution, it is hard to secure funding to save a frog afflicted with it. Why save a frog that is dying through no fault of ours?

What do you think? Should funding be set aside to save species from extinction if they are becoming extinct through natural causes? Or should we focus our resources on trying to save species that are facing extinction as a direct result of our actions?

Jan
14
2005

In August 1995, schoolchildren found deformed frogs in a wetland near Henderson, Minnesota. Some frogs had extra legs, others no legs at all. Some had missing or extra eyes, toes, or feet. And some also had problems with their internal organs. By the fall of 1996, there were over 200 reports of freakish frogs, from two-thirds of Minnesota's counties. Deformed frogs have since been found in 44 states.

Deformed frog: This frog has two right back legs. Others have been found with missing legs, missing parts of legs, or legs in unexpected places.
Deformed frog: This frog has two right back legs. Others have been found with missing legs, missing parts of legs, or legs in unexpected places.Courtesy Minnesota Pollution Control Agency

A 1997 study raised frogs in the lab, mixing pure water with water from two Minnesota sites that had lots of deformed frogs. The more pond water that was used, the more likely the lab frogs were to be deformed. Water from sites with healthy frogs produced healthy animals in the lab. The scientific conclusion was, "There's something in the water." But what could it be? Since then, several researchers have been hunting for the cause.

Scientists have proposed several explanations for the deformities. It may be parasites, chemicals, ultraviolet light, or some combination of the three. Lab studies have shown that all of these factors, alone or in combination, can cause some deformities. But no single cause seems to explain it all. The research doesn't yet add up to a neat and tidy answer, so scientists continue to puzzle out the story.

Who cares about frogs? You should. If there's something wrong with the water, it may eventually hurt all of us. But it will hurt frogs first. Frogs have thin skins, and easily absorb any contaminants in the water. Frogs seem to be in trouble all around the world. There are more and more reports of deformities. And some species have disappeared, or no longer live in their old habitats. It's a wide-spread problem that may affect us all.