theories

Orcas Versus Boats | Earth Wise

July 11, 2023 By EarthWise Leave a Comment

Over the past three years, orcas (also known as killer whales) have been attacking boats off the coasts of Portugal and Spain. The subpopulation of orcas in this region has been harassing boats, most often by biting at their rudders.

There have been over 500 reported instances of orcas reacting to boats. Sometimes they simply approach the vessels, but some of the time they actually attack. Almost 20% of the attacks have caused enough damage to disable the vessels. In three cases, including one in May in the Strait of Gibraltar, the animals damaged a boat so badly that it sank. To date, no one has been injured during these attacks.

Orca researchers have observed several different killer whales during these attacks. They seem to come from two separate groups: a trio of juveniles occasionally joined by a fourth, as well as a mixed-age group consisting of an adult female, two of her offspring, and two of her sisters. The attacks typically last less than 30 minutes but can go on for up to 2 hours.

Researchers don’t really know why orcas are going after watercraft. This behavior has not been observed anywhere else in the world. One theory is that the orcas have invented a new fad. That’s actually something that they are known to do. Much as with people, orca fads are often spearheaded by juveniles. An alternative theory is that the attacks may be a response to a bad past experience involving a boat. The fact that nobody has been injured in any of these attacks, even when the boats sank, suggests that only the boats themselves are the target of the attacks and not the people on them.

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Why Has a Group of Orcas Suddenly Started Attacking Boats?

Photo, posted May 24, 2023, courtesy of Pedro Szekely via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Mosquito Magnets | Earth Wise

November 30, 2022 By EarthWise Leave a Comment

We’ve all probably had the experience of being in the great outdoors with other people and having some of them being nearly devoured by mosquitoes while others didn’t get bitten at all. It seemed like some people are mosquito magnets while others just aren’t the insects’ cup of tea, so to speak.

There have been various theories proposed over the years including such things as it being a question of blood type, or it having to do with how close one’s blood vessels are to their skin surface.

A new study by the Howard Hughes Medical Institute and the Rockefeller University has uncovered what appears to be the real explanation. According to the paper published in the journal Cell, certain body odors are the deciding factor. Every person has a unique scent profile associated with different chemicals present on their skin. The researchers found that people whose skin produces high levels of carboxylic acids are the most attractive to mosquitos.

The researchers collected scent samples from participants by having them wear silk stockings on their arms for six hours. The nylons were then cut into pieces and the pieces exposed to mosquitos. After several months of head-to-head battles between various nylon samples, the study clearly demonstrated that the samples from subjects with higher levels of carboxylic acids in the skin were far more attractive to mosquitos.

Humans produce the substance at much higher levels than other animals. There is little one can do about their own levels. Changing one’s diet or what soap they use doesn’t seem to make a difference.

Perhaps researchers can come up with some method of breaking down carboxylic acids in the skin in the future. Until such time, there are really people who are mosquito magnets.

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Some People Really Are Mosquito Magnets, and They’re Stuck That Way

Photo, posted September 4, 2014, courtesy of James Gathany / Centers for Disease Control via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Narwhal Tusks And Stories Teeth Can Tell | Earth Wise

February 4, 2020 By EarthWise Leave a Comment

Teeth and particularly narwhal tusks are getting some unusual press recently when one of them was the weapon of choice to fend off the London Bridge attacker, which was a good choice according to Harvard dental researcher Dr. Martin Nweeia. Turns out that narwhal tusks have some pretty amazing physical features. They exhibit both extreme strength and flexibility at the same time. The narwhal is known as the unicorn of the sea, a pale-colored, medium-sized whale found in Arctic coastal waters and rivers. In males, the more prominent tooth grows into a sword like, spiral tusk up to 8.8 feet long.

Changes in the shape of teeth over time can tell us about climate change. Adaptations in horse teeth 55 million years ago from North America were observed and caused by changes in climate, favoring different food sources. The horses changed their diets from fruit to more favorable grasses and their teeth changed in response. For this same reason, the teeth of elephants adapting in different environments of Asia and Africa have different tooth forms. Both eat plants but Asian elephants, with more ridges on their teeth, eat larger amounts of grasses while African elephants, with wider spread ridges, eat more leaves.

Teeth have been used to link land mass theories like the Bering Land Strait Theory, hypothesizing that North America and Asia were once one land mass. The teeth shape and form of people on both sides of the Bering Land Bridge shared a common “mongoloid dentition” with unique features. And so, can the narwhal tusk tell us something about a changing Arctic? Scientists have discovered that the narwhal tusk is a giant sensory organ that is able to continually monitor its environment and has the ability to detect ice formation, and melt, both capabilities helpful for surviving in a changing Arctic.

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–Earth Wise acknowledges script contribution from Dr. Martin Nweeia of Harvard University.

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Fossil teeth reveal new facts about a mass extinction 260 million years ago

From the Horse’s Mouth: Teeth Reveal Evolution

Photo, posted April 3, 2019, courtesy of James St. John via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.