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Life Signs
A Space Daily column

Life Signs

Nature and earth science

Life Signs is where Space Daily looks down instead of up. Animals, ecosystems, and Earth science, with a bias for peer-reviewed studies over press-release hype. The living world turns out to be at least as strange as anything in orbit.

Science

The axolotl can regrow a lost leg, a piece of its heart, parts of its spinal cord, and even sections of its brain with no scarring, and yet in the wild it survives in a single network of canals on the outskirts of Mexico City, where fewer than 1,000 individuals are thought to remain

The axolotl rebuilds limbs, heart tissue, spinal cord and parts of its brain without scarring — yet the wild population survives only in the canals of Xochimilco, where fewer than a thousand adults remain.

Science

The blue whale’s heart weighs about 400 pounds, beats as slowly as twice per minute when the animal is deep-diving, and pushes blood through an aorta about nine inches across, wide enough to fit a human head but not the crawling child of the popular legend

A blue whale's heart weighs 400 pounds, slows to two beats a minute on deep dives, and pushes blood through an aorta the width of a dinner plate. The first specimen ever fully preserved rewrote nearly everything textbooks claimed about its size.

Science

We tend to picture glaciers as slow rivers of white ice, but the Blood Falls that leak from Antarctica’s Taylor Glacier run a deep rust red, fed by a briny lake sealed under the ice for roughly 1.5 million years that hosts microbes living without sunlight or oxygen

Blood Falls, the rust-red outflow at the terminus of Antarctica's Taylor Glacier, is fed by a briny reservoir sealed under the ice for at least a million years. A new Nature Geoscience study finds an active community of marine-associated microbes still living inside it, without sunlight or oxygen.

Climate Science

We tend to picture glaciers as slow rivers of frozen water, but the Byrd Glacier in Antarctica drains an area larger than California through a gap in the Transantarctic Mountains at up to 800 metres a year, dragging enough ice to raise global sea level measurably if it ever fully released

Byrd Glacier drains an East Antarctic catchment larger than California through a 24-kilometre gap in the Transantarctic Mountains, moving at up to 800 metres a year — and its behaviour is set by a bedrock trough carved before the dinosaurs.

Science

Bristlecone pines growing in the White Mountains of California include one individual that germinated around 3050 BCE, meaning it was already 500 years old when the first stones of the Great Pyramid at Giza were cut, and it is still putting out needles this year

A Great Basin bristlecone pine in California's White Mountains, sampled by researcher Tom Harlan, germinated around 3050 BCE — five centuries before the Great Pyramid was built — and is still alive today. Its exact location is a Forest Service secret.

Science

Off the coast of Japan, a jellyfish smaller than a fingernail called Turritopsis dohrnii responds to injury or starvation by collapsing back into a blob on the seafloor and regrowing into a juvenile polyp, effectively resetting its life cycle with no known upper limit on how many times it can do it

A 4.5-millimetre jellyfish off the coast of Japan responds to injury or starvation by collapsing into a blob and regrowing as a juvenile polyp — with no known upper limit on how many times it can reset its own life cycle.

Tectonics

The Peruvian Amazon holds a river that runs hot enough to boil small animals that fall in, reaching 86 degrees Celsius along a 6-kilometre stretch with no volcano anywhere nearby, and geologists think it is heated by water circulating several kilometres deep through faults in the rock

A tributary in the Peruvian Amazon reaches 86 degrees Celsius along a six-kilometre stretch, with no volcano within 700 kilometres. Geologists trace the heat to rainwater circulating kilometres deep through faults before rising back to the surface.

Science

Enceladus appears to have almost everything life should need — water, chemistry, hydrothermal energy and an ocean capable of lasting geological ages. If we search it thoroughly and find nothing alive, that failure may become one of astrobiology’s most important discoveries: evidence that habitability alone is not enough to make life happen.

Cassini established that Enceladus may be habitable, but a scientifically useful failure to find life would require repeated, complementary measurements designed to make a false negative unlikely.