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Why Do Whales Beach Themselves?

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Humans have observed marine mammals stranding themselves on land since at least the first century CE, when the ancient Romans and Greeks recorded beaching incidents. Modern marine biologists are only able to determine the cause of a beaching about 50 percent of the time, according to the Woods Hole Oceanographic Institution, and the reasons they find are varied.

Often the cause is obvious injury or illness. Disease or wounds from predators can leave an animal too weak to keep itself afloat, and at some point it gives up and lets the tides wash it ashore.

Cases where a group of animals beach themselves together, and not all of them exhibit signs of trauma, are more puzzling. One explanation biologists offer is that whales and dolphins, which hunt and travel together in groups called pods, fall victim to their own social structure. If the group leader or dominant animal is sick or hurt and runs ashore, the rest of the group might follow. Other times, the pod may just get itself stuck by a low tide after hunting or traveling too close to shore.

In some instances, mass beachings have occurred shortly after active use of military sonar in an area. In 2000, for example, 17 animals from four species (Cuvier’s beaked whale, Blainville’s beaked whale, Minke whale, and the spotted dolphin) were found beached within a 36 hour period in the Bahamas the day of, and after, a U.S. Navy sonar exercise. A joint Navy and National Oceanic and Atmospheric Administration (NOAA) investigation soon concluded that the tactical mid-range frequency sonars used by the Navy ships “were the most plausible source of the acoustic or impulse trauma” that occured. The evidence suggests that sonar may have both physical and behavioral effects on marine mammals.

Some animals also beach themselves purposefully as a hunting tactic. Killers whales, or orcas, frequently chase pinnipeds, like seals and sea lions, into the surf zone and onto shore, where the prey has to make a clumsy transition from swimming to walking in shallow, turbulent water. As the prey struggles to escape, the orca launches itself, or rides a wave, onto the beach and grabs the prey in its jaws. After the meal is secured, the orca can either wriggle back into deeper water or let a large wave lift it off the ground and back out to sea.

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Sylke Rohrlach, Wikimedia Commons // CC BY-SA 4.0
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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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This Just In
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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