Science Links of the Week

A passion for the natural world drives many of our adventures. And when we’re not actually outside, we love delving into the discoveries about the places where we live and travel. Here are some of the best natural history links we’ve found this week.

Life on the Great Pacific Garbage Patch: In 2019, Benoit Lecomte swam through the Great Pacific Garbage patch to raise awareness about plastic pollution. The patch, between Hawaii and California, contains 79,000 tonnes of plastic litter.

As he swam, he noticed marine life around him. In some areas, there were almost many surface-dwelling organisms as plastic. The ginormous floating rubbish pile had become a habitat.

Researchers think the same gyres that cause the rubbish to accumulate have also brought in marine wildlife. They worry that this newly discovered life among the plastic will stall conservation efforts.

An unusual monkey pairing

Hybrid monkeys in Borneo: In 2017, a photographer captured an unknown species of monkey in Borneo. At the time, the monkey was a juvenile, so researchers struggled to identify the creature. Over the years, more photos and in-person observations formed a better understanding of this animal, now a mature female.

The monkey seems to be a hybrid of two species that share the same habitat, a proboscis monkey and a silvery langur. “She appeared to be nursing a baby. We were all in awe,” said primatologist Nadine Ruppert.

It is very rare for different species to mate and produce viable offspring. In these few cases, both species are very similar. But proboscis monkeys and silvery langurs do not even belong to the same genus.

“We concluded that male proboscis monkeys are mating with female silver langurs…and that there are mixed groups where female proboscis monkeys even take care of silver langur babies,” Ruppert said.

A yellow turtle against silhouettes of hundreds of tropical fish.

Hawksbill sea turtle Photo: Shutterstock

 

A turtle’s sense of direction is pretty bad, actually

Migrating sea turtles don’t know where they are going: Researchers have made new inroads into that baffling old question, how do migratory animals know where to go? In the case of sea turtles, most of the time they do not.

Scientists tracked the movement of hawksbill turtles as they swam from their breeding grounds in one archipelago in the Indian Ocean to various foraging sites. Over shorter distances, they zigzagged their way until they happened upon their destination. Most of the time, they swam double the straight-line distance. In one case, a particularly erratic turtle swam 1,306km to reach a place that was 176km away.

As marine scientist Graeme Hays put it, “They are almost certainly are using a geomagnetic map, but it’s a fairly coarse resolution.”

They use this ‘map’ to reach the general area they are seeking, then use visual landmarks and scent to home in on their final destination.

Female octopuses self-mutilate to death after laying eggs: After laying their eggs, female octopuses stop eating and eventually starve themselves. By the time the eggs hatch, the mothers are dead.

This unusual maternal behavior occurs because of the octopuses’ optic gland. Somehow, it changes cholesterol metabolism, and in turn, steroid hormones. Steroids increase in three ways after reproduction. First, the octopus produces steroids necessary for pregnancy. Second, they produce bile acid. Third, they increase levels of a particular chemical called 7-DHC, which is a precursor to cholesterol. In humans, raised 7-DHC levels are a symptom of a genetic disorder known to cause repetitive self-injury. This is mirrored by female octopuses.

Dolphins’ beauty secrets

Corals are dolphin skincare: Biologist Angela Ziltener was diving in the Indo-Pacific when she noticed dolphins lining up to brush themselves against corals. Ziltener observed this many times and came up with a theory. She believes that the rubbing transfers antibacterial compounds and antioxidants from the corals and sea sponges to the dolphins’ skin.

The dolphins only show this behavior with gorgonian and leather corals. These corals contain 10 antibacterial compounds, which help the dolphins maintain healthy skin.

Two dolphins swimming, one over the other

Bottlenose dolphins rub themselves on coral. Photo: Shutterstock

 

Feral pigs boost crocodile numbers: In the 1970s, crocodile numbers in Australia were at an all-time low because of unregulated hunting. Since then, conservationists and the government have worked to protect them. Over 100,000 crocodiles now live in the Northern Territory.

One of the reasons for this success is the crocodiles’ change in diet. Researchers compared the naturally occurring carbon and nitrogen isotopes in crocodile bone and tissues. Over the last 50 years, carbon-13 and nitrogen-1 have decreased. This showed that crocodiles are moving away from a marine estuary-based diet. Instead, they feast on feral pigs and buffalo. Feral pigs are an invasive species, and the crocodile boom has helped control the damage these pigs cause.

Rebecca McPhee is a freelance writer for ExplorersWeb.

Rebecca has been writing about open water sports, adventure travel, and marine science for three years. Prior to that, Rebecca worked as an Editorial Assistant at Taylor and Francis, and a Wildlife Officer for ORCA.

Based in the UK Rebecca is a science teacher and volunteers for a number of marine charities. She enjoys open water swimming, hiking, diving, and traveling.

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