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Hoving and Haddock, Scientific Reports (2017)
Hoving and Haddock, Scientific Reports (2017)

Giant Seven-Arm Octopus Might Use Jellyfish as a (Tasty) Weapon

Hoving and Haddock, Scientific Reports (2017)
Hoving and Haddock, Scientific Reports (2017)

The giant deep-sea octopus Haliphron atlanticus does not mess around when it comes to dinner. Scientists have observed several of these cephalopods eating jellyfish in a way that indicates they could be using their stinging prey as tools to capture other snacks, according to New Scientist.

The researchers, writing in Scientific Reports, observed three H. atlanticus using remotely operated submarines from the Monterey Bay Aquarium Institute, as well as by studying the stomach contents of already-caught octopuses. They encountered two that seemed to be holding something gelatinous in their arms, though the researchers couldn’t be certain what the objects were. A third was definitively holding an egg-yolk jelly in its arms by the bell. The octopus was swimming with the jelly’s tentacles still hanging out, but it had bitten through the bell with its beak.

Giant deep-sea octopuses like H. atlanticus—commonly known as the seven-arm octopus because it keeps one arm permanently tucked away, and which can grow to more than 13 feet—are so rare to observe that scientists don’t entirely know what they eat, making these sightings particularly exciting. Other octopus species have been known to dine on fish or crustaceans, but H. atlanticus apparently targets gelatinous creatures.

Based on their observations and previous records of other cephalopods, such as the palmate octopus, the researchers speculate that beyond using jellies as a food source, H. atlanticus could be using them as weapons to catch other prey. “Haliphron may target the stomach contents of the [jellyfish], or even use the [jellyfish] as a tool to obtain more nutritious prey that are captured by the fringe of tentacles clasped within the octopus arms,” they write.

However, using their food as a tool might not be the only reason the seven-armed octopuses eat jellies the way they do. The researchers note that fish and sea turtles also target the oral arms and gonads of jellies for eating, since those are energy-dense areas of the jelly body. This study doesn’t settle the case of what these octopus do with those jellies, exactly, but it provides tantalizing evidence that they could be using their food to catch other food. It wouldn't be their only scary-smart skill.

[h/t New Scientist]

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Ocean Waves Are Powerful Enough to Toss Enormous Boulders Onto Land, Study Finds
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During the winter of 2013-2014, the UK and Ireland were buffeted by a number of unusually powerful storms, causing widespread floods, landslides, and coastal evacuations. But the impact of the storm season stretched far beyond its effect on urban areas, as a new study in Earth-Science Reviews details. As we spotted on Boing Boing, geoscientists from Williams College in Massachusetts found that the storms had an enormous influence on the remote, uninhabited coast of western Ireland—one that shows the sheer power of ocean waves in a whole new light.

The rugged terrain of Ireland’s western coast includes gigantic ocean boulders located just off a coastline protected by high, steep cliffs. These massive rocks can weigh hundreds of tons, but a strong-enough wave can dislodge them, hurling them out of the ocean entirely. In some cases, these boulders are now located more than 950 feet inland. Though previous research has hypothesized that it often takes tsunami-strength waves to move such heavy rocks onto land, this study finds that the severe storms of the 2013-2014 season were more than capable.

Studying boulder deposits in Ireland’s County Mayo and County Clare, the Williams College team recorded two massive boulders—one weighing around 680 tons and one weighing about 520 tons—moving significantly during that winter, shifting more than 11 and 13 feet, respectively. That may not sound like a significant distance at first glance, but for some perspective, consider that a blue whale weighs about 150 tons. The larger of these two boulders weighs more than four blue whales.

Smaller boulders (relatively speaking) traveled much farther. The biggest boulder movement they observed was more than 310 feet—for a boulder that weighed more than 44 tons.

These boulder deposits "represent the inland transfer of extraordinary wave energies," the researchers write. "[Because they] record the highest energy coastal processes, they are key elements in trying to model and forecast interactions between waves and coasts." Those models are becoming more important as climate change increases the frequency and severity of storms.

[h/t Boing Boing]

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Climate Change Is Making Nearly All Sea Turtles Born on These Beaches Female
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Climate change can wipe out a species's food source and destroy its habitat, but rising temperatures are having a more surprising effect on green sea turtles that's no less devastating. According to a report in Current Biology [PDF], up to 99.8 percent of the green sea turtles born on certain beaches in Australia are female, a direct result of the area's warmer-than-average temps.

A turtle's sex is determined by its environment. As The Washington Post reports, a clutch of eggs that incubates in sand that's roughly 85°F will produce about 50 percent females and 50 percent males. A few degrees cooler and the batch skews male; a bit hotter and it's majority female.

This evolutionary mechanism tends to balance itself out, but on beaches in northeast Australia, it's being hijacked by climate change. In order to gauge the size of the impact, researchers with the National Oceanic and Atmospheric Administration sampled the nesting beaches along the coast of Australia adjacent to the Great Barrier Reef, the part that has seen the most dramatic temperature rises and coral bleaching. What they found on the warmer northern beaches was the worst-case scenario: 99.1 percent of juveniles, 99.8 percent of subadults, and 86.8 percent of the overall population was female. Data taken from the southern beaches are only slightly less alarming: Turtles hatched in the relatively cooler sands there were still 65 to 69 percent female. According to the study's authors, "the complete feminization of this population is possible in the near future." That would affect the species' future population growth.

Green sea turtles aren't the only species vulnerable to huge sex shifts by way of climate change. Many other reptiles also rely on temperature-dependent sex determination to keep populations balanced. But above-average temperatures can do more harm beyond messing with sex development: It can also kill embryos before they have the chance to hatch. The authors emphasize that figuring out how to regulate sand temperatures at key rookeries will be essential moving forward. If not, the species could face "a population collapse—or even extinction."

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