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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
Scientists Discover 'Octlantis,' a Bustling Octopus City
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Sylke Rohrlach, Wikimedia Commons // CC BY-SA 4.0

Octopuses are insanely talented: They’ve been observed building forts, playing games, and even walking on dry land. But one area where the cephalopods come up short is in the social department. At least that’s what marine biologists used to believe. Now a newly discovered underwater community, dubbed Octlantis, is prompting scientists to call their characterization of octopuses as loners into question.

As Quartz reports, the so-called octopus city is located in Jervis Bay off Australia’s east coast. The patch of seafloor is populated by as many as 15 gloomy octopuses, a.k.a. common Sydney octopuses (octopus tetricus). Previous observations of the creatures led scientists to think they were strictly solitary, not counting their yearly mating rituals. But in Octlantis, octopuses communicate by changing colors, evict each other from dens, and live side by side. In addition to interacting with their neighbors, the gloomy octopuses have helped build the infrastructure of the city itself. On top of the rock formation they call home, they’ve stored mounds of clam and scallop shells and shaped them into shelters.

There is one other known gloomy octopus community similar to this one, and it may help scientists understand how and why they form. The original site, called Octopolis, was discovered in the same bay in 2009. Unlike Octlantis, Octopolis was centered around a manmade object that had sunk to the seabed and provided dens for up to 16 octopuses at a time. The researchers studying it had assumed it was a freak occurrence. But this new city, built around a natural habitat, shows that gloomy octopuses in the area may be evolving to be more social.

If that's the case, it's unclear why such octo-cities are so uncommon. "Relative to the more typical solitary life, the costs and benefits of living in aggregations and investing in interactions remain to be documented," the researchers who discovered the group wrote in a paper published in Marine and Freshwater Behavior and Physiology [PDF].

It’s also possible that for the first time in history humans have the resources to see octopus villages that perhaps have always been bustling beneath the sea surface.

[h/t Quartz]

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Criminal Gangs Are Smuggling Illegal Rhino Horns as Jewelry
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Valuable jewelry isn't always made from precious metals or gems. Wildlife smugglers in Africa are increasingly evading the law by disguising illegally harvested rhinoceros horns as wearable baubles and trinkets, according to a new study conducted by wildlife trade monitoring network TRAFFIC.

As BBC News reports, TRAFFIC analyzed 456 wildlife seizure records—recorded between 2010 and June 2017—to trace illegal rhino horn trade routes and identify smuggling methods. In a report, the organization noted that criminals have disguised rhino horns in the past using all kinds of creative methods, including covering the parts with aluminum foil, coating them in wax, or smearing them with toothpaste or shampoo to mask the scent of decay. But as recent seizures in South Africa suggest, Chinese trafficking networks within the nation are now concealing the coveted product by shaping horns into beads, disks, bangles, necklaces, and other objects, like bowls and cups. The protrusions are also ground into powder and stored in bags along with horn bits and shavings.

"It's very worrying," Julian Rademeyer, a project leader with TRAFFIC, told BBC News. "Because if someone's walking through the airport wearing a necklace made of rhino horn, who is going to stop them? Police are looking for a piece of horn and whole horns."

Rhino horn is a hot commodity in Asia. The keratin parts have traditionally been ground up and used to make medicines for illnesses like rheumatism or cancer, although there's no scientific evidence that these treatments work. And in recent years, horn objects have become status symbols among wealthy men in countries like Vietnam.

"A large number of people prefer the powder, but there are those who use it for lucky charms,” Melville Saayman, a professor at South Africa's North-West University who studies the rhino horn trade, told ABC News. “So they would like a piece of the horn."

According to TRAFFIC, at least 1249 rhino horns—together weighing more than five tons—were seized globally between 2010 and June 2017. The majority of these rhino horn shipments originated in southern Africa, with the greatest demand coming from Vietnam and China. The product is mostly smuggled by air, but routes change and shift depending on border controls and law enforcement resources.

Conservationists warn that this booming illegal trade has led to a precipitous decline in Africa's rhinoceros population: At least 7100 of the nation's rhinos have been killed over the past decade, according to one estimate, and only around 25,000 remain today. Meanwhile, Save the Rhino International, a UK-based conservation charity, told BBC News that if current poaching trends continue, rhinos could go extinct in the wild within the next 10 years.

[h/t BBC News]

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