marine biology

Competition Pressured Killer Whales Into Menopause

Selfish daughters, not altruistic grandmothers, could explain the evolution of menopause.

Surviving beyond the end of your reproductive life is a rare trait: only female humans, killer whales, and short-finned pilot whales are known to do it. The question is why?

If the purpose of life is to pass on your genes, as evolutionary biologists suggest, then an end to reproductive ability—menopause—really just makes no sense. Read more in Hakai Magazine.

Sword-slashing sailfish hint at origins of cooperative hunting

Cooperation makes it happen. Sailfish that work together in groups to hunt sardines can catch more fish than if they hunt alone, even without a real coordinated strategy.

To catch their sardine dinner, a group of sailfish circle a school of sardines – known as a baitball – and break off a small section, driving it to the surface.

They then take turns attacking these sardines, slashing at them with their long sword-like bills, which account for a quarter of their total length of up to 3.5 metres. Knocking their prey off-balance makes them easier to grab.

These attacks only result in a catch about 25 per cent of the time, but they almost always injure several sardines. As the number of injured fish increases, it becomes ever easier for everyone to snag a meal. Read more in New Scientist.

Keeping Track of Deep-Sea Mining

A new website uses ship location data to track deep-sea mining exploration.

Mining companies have claimed more than a million square kilometers of ocean around the world and soon—maybe sooner than you think—will begin sending huge robotic diggers to grind up the seafloor and extract gold, copper, manganese, and other metals to feed our growing hunger for raw materials. Read more in Hakai.

Surfing on a turtle’s tail makes swinging crabs monogamous

Surfing the world’s oceans on the back of a turtle may sound like a life of luxury, but for a small crab it also means restricting itself to a single mate.

A species of small oceanic crab, Planes minutus often makes its home on the shells of loggerhead turtles. They tuck themselves into a tiny space above the turtle’s tail and below the shell, just the right size for a pair of crabs – a male and a female living in a simple monogamous relationship.

But these crabs will also make their homes on floating debris, where they nestle among stalked barnacles, and often enjoy a more swinging, polyamorous lifestyle. Read more in New Scientist.

Are we ready for the gold rush on the sea floor?

One firm reckons its planned sea-floor mines are more sustainable than those on land. But the diggers could destroy rare life and more.

THE submersible Alvin encountered its first “black smoker” 2000 metres deep off the coast of the Galapagos Islands. It was 1977, and the realisation that life could survive in pitch darkness next to deep sea hydrothermal vents was about to stun the world. Now we are returning to those vents, this time on the other side of the Pacific – and armed with diggers.

The hot water shooting out of these vents contains all sorts of dissolved precious metals. On contact with the cold ocean water, these immediately precipitate out, showering the vicinity with gold, silver, copper and more. Some want to tap into this booty, arguing that deep sea mining is not only lucrative, but also a more sustainable alternative to mineral extraction on land. But not everyone is convinced we can exploit the deep without damaging it. Read more in New Scientist.

Watch a baby sea turtle being hypnotised so we can weigh it

Baby sea turtles are an energetic bunch. As soon as they emerge from their sandy nests they scramble down the beach and swim out to sea. This frantic burst of activity helps the turtles evade predators, but it can be a real headache for researchers who want to gather measurements from these tiny, squirming subjects.

“We often heard about novice researchers dropping hatchlings,” says Mohd Uzair Rusli, a biologist at the University of Malaysia Terengganu in Kuala Terengganu. A drop in the lab from table height can be deadly, damaging their fragile internal organs. Read more in New Scientist.

Tentacled sea creatures are taking over the Earth’s oceans

Octopuses and their tentacled brethren are taking over the seas, as ocean temperatures climb and humans snaffle up their natural predators.

Zoe Doubleday, a marine biologist at the University of Adelaide in Australia, and her colleagues were studying an iconic local species, the giant Australian cuttlefish, which had been in decline for several years.

Doubleday wanted to see whether it was part of a larger cyclical trend in global populations, so she looked at data from surveys and from cephalopod fisheries and cephalopod bycatch in finfish fisheries between 1953 and 2013.

To her surprise she found a consistent increase in cephalopod populations over the past six decades, in species from all over the world and in every habitat, from the deep ocean to the near-shore shallows. Read more in New Scientist.

Baby turtles work together to dig themselves out of a nest hole

Baby sea turtles work together to dig their way out of sandy nests, and the more of them there are, the less energy they use doing it.

We knew of this group-digging behaviour, called social facilitation, for a long time, but the reasons for teamwork were unclear. Possible explanations included speeding up nest escape or helping the turtles emerge together to swamp awaiting predators on the beach. Read more in New Scientist.