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Why Do Students Dissect Frogs?

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There are many surgeons who say that they first discovered their life’s passion standing over a dissected frog in a middle or high school biology class. But, apart from inspiring the medical professionals of tomorrow, what is the purpose of dissection? And more importantly, why is everyone always dissecting those poor green amphibians?

There are many reasons that students in biology classes are asked to perform dissections, and they have a lot to do with understanding the body and the wider world. In dissecting an animal, students see, touch, and explore the various organs in the body. Seeing these organs and understanding how they work within a single animal allows students to understand how these systems work within many other animals, including themselves. While there are various aspects that may differ between humans and other animals, many of the organ systems in complex animals work in similar ways to those of humans.

One reason frogs are often chosen to be dissected is that their bodies provide a good overview of the organ systems of a complex living thing. While the way their bodies work is nowhere near identical to a human’s, there are many similarities. The organs present in a frog, and the way they are laid out in the body, are similar enough to humans to provide insight for students about how their bodies work.

In addition to learning about themselves, students can learn about ecology and evolution through frog dissection. Certain body structures and adaptations can be seen in frogs that illustrate how they evolved over time and how they fill particular niches in the ecosystems they belong to. For example, the tongue of a frog has adapted to have great length, strength, and speed in order to effectively catch insects in flight. The role that this tongue allows the frog to fulfill—consuming insects as its primary food source—is important in the balance of many ecosystems the frog is a part of.

There are practical advantages in using frogs, too. They're an appropriate size for dissection in the classroom and make the process manageable for students and teachers. Also, frogs have a relatively short life span to begin with, and while some species are rare in some places, others are abundant and are therefore prime candidates for use in dissection. Bullfrogs, for example, are an invasive species in much of the United States. While they naturally help to control insect populations, they are also threatening native populations of other animals. This is especially the case when it comes to other frogs—bullfrogs are known to eat other frogs and drive other frog species out of their natural habitats. Bullfrogs, while not the only frogs used for dissection, are among the most common. The use of these frogs serves a dual purpose, controlling their populations and providing a learning experience at the same time.

While it is true that many people, for many different reasons, oppose dissection in the classroom, and offer alternatives like models or online options, dissection is still a valued educational tool thanks to its hands-on nature. It is thought that if students see and feel these organ systems for themselves, they will take more out of the lesson than if the teacher just lectured or assigned readings about it. Also, some teachers express the hope that by learning about their own bodies through dissection, students will come to respect how their bodies work, and think about how they treat them and what they put into them.

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Animals
This Octopus Species in Northern Australia Can Hunt on Dry Land
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YouTube

Most octopuses live in the ocean—but in northern Australia, a small, shallow-water species takes to land in search of food. Abdopus aculeatus is the only octopus that’s specially adapted to walk on dry ground. Using its long, sucker-lined arms, the slimy sea creature pulls itself along the shoreline as it searches tide pools for crabs.

Witness Abdopus aculeatus in action by watching BBC Earth’s video below.

[h/t BBC Earth]

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Weather Watch
Rising Temperatures Are Killing Off African Wild Dogs
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Over the last few decades, images of fluffy white harp seals, polar bears, and penguins have become shorthand for climate change's creeping destruction of our planet. But the poles aren't the only ecosystems in danger. A new study published in the Journal of Animal Ecology finds that rising temperatures near the equator are making it much harder for African wild dogs to survive.

"When people think about climate change affecting wildlife, they mostly think about polar bears," lead researcher Rosie Woodroffe of the Zoological Society of London told The Guardian. "But wild dogs are adapted to the heat—surely they'd be fine."

To find out, Woodroffe and her colleagues analyzed data from packs of African wild dogs (Lycaon pictus) in Kenya, Botswana, and Zimbabwe. The dog packs have been under scientist surveillance for years—some since the late 1980s—and at least one dog per pack is fitted with a radio collar.

The researchers overlaid information about local weather and temperature with data on the dogs' hunting habits, the size of each litter of pups, and how many pups from each litter survived.

These dogs are creatures of habit. Adults rise early and leave the den for a morning hunt. They range over their large territories, chasing antelopes. At midday, when the Sun is highest, they return to their pups with food. They may go out again in the evening as the temperature drops.

But like the polar bears' glaciers, the dogs' environment is gradually heating up. All three countries saw a temperature increase of about 1.8°F over the study period. This may not sound like much, but for the dogs, it was plenty. Between 1989 and 2012, the number of pups per litter in Botswana surviving to their first birthday dropped from 5.1 to 3.3. Dog packs in Zimbabwe saw a 14 percent decrease in pup survival; in Kenya, the rate declined by 31 percent.

"It's really scary," Woodroffe said.

"If you are an animal who makes your living by running around really fast, obviously you are going to get hot. But there are not enough hours in the day anymore that are cool enough to do that. It is possible that some of these big areas will become too hot for wild dogs to exist."

Woodroffe and her colleagues were not anticipating such clear-cut results. "It is shocking and surprising that even right on the equator these effects are being seen," she said. "It illustrates the global impact of climate change." 

[h/t The Guardian]

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