Watch humpback whales trick thousands of fish into becoming dinner

The humpback whale has one of the biggest mouths on the planet—and the appetite to match. The bus-size mammals can eat up to 2500 kilograms of fish a day, and a new study reveals one way they snag these huge numbers: They make the fish come to them.

Humpbacks were already known to have a few hunting tricks up their sleeve. They blow bubbles in giant circles around herring to herd them into tightly grouped schools that can be swallowed whole. They also “power thrust” into dense balls of young herring, catching the fish by surprise.

Read more at Science. 

Watch the Captivating Courtship Dance of Manta Rays

For the past 14 years, scientists have been watching manta rays pick each other up at a known hotspot in the Maldives, recording 229 courtship events. They recently compiled their observations into a report that is, according to Guy Stevens, founder of Manta Trust and lead author, “the most detailed window into the sex lives of mantas.”

While the two species of manta rays documented in the study, giant oceanic manta rays and reef manta rays, mate in different places and usually at different times of the year, their mating rituals are quite similar.

Read more at Hakai.

Sneaky Arrow Squid Prevent Females from Using Other Males’ Sperm

In a form of imposed contraception, some arrow squid males prevent their female consorts from fertilizing their eggs with another male’s sperm.

Arrow squid aren’t particularly loyal. Females mate with several males and can even store the sperm from such liaisons in special receptacles for future use. New research led by Luiza Saad, a doctoral candidate in zoology at the University of São Paulo in Brazil, however, shows that certain males have evolved a strategy to get ahead of the competition: they lodge a tube-like plug into the female’s reproductive tract, blocking her ability to use stored sperm.

Read more at Hakai.

Lost shark seen for first time in a decade – in a fish market

The Ganges river shark is so rare that there has been no confirmed record of the species for a decade – and very few ever. But a series of photographs taken at a fish market in Mumbai, India, show the species is still around, and in a unexpected place.

“It’s a species that’s never really been seen in the western Indian Ocean,” says Rima Jabado, founder and lead scientist of the Gulf Elasmo Project – a shark research and conservation organisation – in the United Arabic Emirates.

Read more at New Scientist.

How Culture Guides Belugas’ Annual Odysseys Across the Arctic

The belugas were due to arrive in droves, but Gregory O’Corry-Crowe was nervous. Just a few years into a postdoctoral biology fellowship, O’Corry-Crowe had taken this opportunity in 1998 to fly to remote Somerset Island in the Canadian Arctic with a pair of seasoned biologists. Would the whales show up?

The whales were not shy about announcing their arrival. After a few days of relatively quiet seas, they roused him in the early hours—night this far north was only a dim concept in the summer—with a “cacophony of noise” caused by their blowing, flapping and humming in the water. O’Corry-Crowe rolled out of his sleeping bag at the seaside camp to a vista of about 1,500 beluga whales.

Read more at Smithsonian Magazine. 

Octopus Chokes Dolphin to Death in First-Ever Discovery

Nobody ever told Gilligan the dolphin not to bite off more than he could chew.

The male Indo-Pacific bottlenose dolphin is the first known cetacean to die from asphyxiation by octopus, a new study says.

He “seems to have been extremely greedy and thought, ‘You know what, I’m going to swallow it whole,'” says study leader Nahiid Stephens, a pathologist at Murdoch University in Perth, Australia.

Read more at National Geographic.

In the Maldives, the Virtues and Limitations of Pole-and-Line Tuna Fishing

KELSEY MILLER, fisheries researcher with a global advocacy group, wobbled for balance on a 50-foot fishing boat as silvery tuna flew through the air towards her. It was 2014, and as the vessel pitched off the coast of the Maldives, a collection of atolls several hundred miles southwest of the southern tip of India, a dozen or so fishermen working in the stern pulled the fish from the water one by one with fishing poles, flipping their catch towards the boat’s bow.

There is one thing that all sides can agree on: Bycatch is a problem for the fishing industry everywhere.

When the fishermen took a break, Miller and her colleagues went to work, hastily counting, weighing, and measuring the fish — along with any other sea creatures, from juvenile sharks to mahi-mahi, that were incidentally caught in the process. The team was conducting research for a study, published in PLOS One last spring, on “bycatch” — the myriad unintended sea creatures captured by fishermen, typically in massive nets as they pursue a commercial species. As the study notes, Miller and her colleagues with the International Pole and Line Foundation, a U.K.-based tuna conservation group that advocates for the less impactful fishing technique, spent more than 100 days monitoring accidental catch — and found surprisingly little.

Read more at Undark. 

Tracking the Scars of Dolphin-Shark Battles

Shark versus dolphin is an epic oceanic battle—pitting brain against brawn, social cooperation against rugged individualism. But while the war has likely run for millions of years, the skirmishes are fleeting, brief, and rarely witnessed.

“They happen so quickly that our chances of seeing them are low,” says Michael Heithaus, a marine ecologist at Florida International University who’s spent years in the water among dolphins and sharks. “I’ve seen one direct interaction in my life,” he says, describing a scene in Western Australia’s Shark Bay when a great white swam toward a pod of dolphins that scattered when they sensed the impending threat.

Read more at Hakai Magazine.

Glow-in-the-Dark, Inflatable Sharks Can Also Reproduce Asexually

Glow-in-the-dark sharks that can inflate their bodies like inner tubes have another hidden talent: asexual reproduction.

In a new study, researchers describe how a female swellshark, one that had been isolated from males for at least three years at National Aquarium facilities in Baltimore, laid eggs that hatched into five baby sharks.

Read more at Hakai Magazine.

Two-Headed Sharks Keep Popping Up—No One Knows Why

Two-headed sharks may sound like a figment of the big screen, but they exist—and more are turning up worldwide, scientists say.

A few years ago off Florida, fishermen hauled in a bull shark whose uterus contained a two-headed fetus. In 2008, another fisherman discovered a two-headed blue shark embryo in the Indian Ocean.

And a 2011 study described conjoined twins discovered in blue sharkscaught in the Gulf of California and northwestern Mexico. Blue sharks have produced the most recorded two-headed embryos because they carry so many babies—up to 50 at at time, says study leader Felipe Galván-Magaña, of the National Polytechnic Institute in Mexico.

Read more at National Geographic.