Field notebook
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Field notebook
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Permanent editions
Published facts keep their original date, evidence and correction trail. Drafts and withdrawn editions are never mixed into this index.
Two-toed amphiumas have one of the largest genomes measured in any animal, roughly twenty-five times the size of a human's. The consequence is visible under a microscope: their red blood cells are among the biggest known in vertebrates.
The tiny teeth on a limpet's rasping tongue are reinforced with goethite nanofibres and reach tensile strengths of roughly three to six and a half gigapascals, exceeding spider silk and matching high-performance engineered fibres.
Sponges have no neurons, yet a glass sponge can arrest its feeding current across the whole body within seconds of a disturbance. The signal travels through continuous cytoplasm, because much of the animal is a single fused syncytium.
A fossil insect from the Messel pit in Germany, Eophyllium messelensis, shows the leaf-like body outline and leg lobes of modern Phyllium. It puts the strategy at least 47 million years old and reveals it evolved among quite different plants.
Beneath the long outer skirt sits qiviut, a downy underlayer shed in sheets each spring. Its fibres measure in the low teens of micrometres, finer than most cashmere, and it is one of the warmest natural fibres collected anywhere.
Cormorants stand with wings spread because parts of their plumage soak up water. That looks like a design flaw, but wet outer feathers reduce buoyancy and make diving cheaper, so the drying posture is the price of an efficient hunt.
Cassiopea settles bell-first on the seabed and points its arms upward because those arms are packed with symbiotic algae. The posture is not distress or stranding: it is a sun-facing arrangement that lets photosynthesis supply a large share of the animal's energy.
Most bony fish carry a gas-filled float that holds them at depth without effort. Atlantic mackerel do not have one, so they must swim continuously to avoid sinking, and can change depth quickly without waiting for gas to equilibrate.
When one bird in a flock was shot, the rest circled back to the fallen individual rather than fleeing. Hunters could therefore take an entire flock from a single position, a behaviour repeatedly described in nineteenth-century accounts.
The family is named for a two-spine mechanism in the dorsal fin. The first spine raises and a smaller second spine slots in behind it as a locking pin, wedging the fish inside a hole so it cannot be pulled out.
Weka are declining across parts of New Zealand and are protected. They are also capable nest raiders, taking eggs and chicks of seabirds and other natives, which has led conservation managers to remove weka from some islands they were introduced to.
Anemonefish are protandrous hermaphrodites. The largest fish in an anemone is female, the second largest is her mate, and when she dies her partner changes sex to replace her rather than a new female arriving.
Pygmy squid have an adhesive organ on the back of the mantle that produces a two-part glue. They stick to seagrass blades, wait motionless, and release on demand without leaving residue.
Roman tradition credits the sacred geese of the Capitol with raising the alarm during a night attack. The practice is not merely ancient: geese have served as working sentries at military installations and distilleries into the modern era.
Every other bird avoids the polar winter. Emperor penguins walk inland onto sea ice as it forms, and males incubate a single egg on their feet through months of darkness and temperatures far below freezing without eating.
For decades nobody knew where Kemp's ridley nested. An amateur film shot at Rancho Nuevo in 1947, rediscovered years later, showed tens of thousands of females on one Mexican beach in a single day, and set the baseline against which the collapse was measured.
Seasonal flooding across an area larger than England concentrates fish into shrinking pools each dry season, and the yacare caiman exploits it. Population estimates for the Pantanal run into the millions, among the densest crocodilian aggregations anywhere.
An American dog tick finds a host by climbing a grass stem and holding out its front legs, a posture called questing. It waits for something to brush past. It cannot jump, cannot fly, and does not drop out of overhead branches.
The hoatzin digests foliage using bacterial fermentation in a greatly enlarged crop, the only bird known to do so. The chamber is so heavy that the bird's flight muscles are reduced to make room for it.
Only some male Asian elephants grow tusks, and females essentially never do. What female and tuskless male Asian elephants have instead are tushes, short teeth that rarely project beyond the lip.
Across hundreds of kilometres, dozens of coral species release eggs and sperm within the same handful of nights each year, cued by water temperature, the lunar cycle and the time after sunset. The water turns visibly cloudy.
Bogong moths fly up to a thousand kilometres to alpine caves they have never visited. Flight simulator experiments showed they combine a magnetic sense with visual landmarks, and that scrambling either one leaves them unable to hold a course.
Cane toads kill northern quolls that try to eat them. Conservation biologists have used sausages of toad meat laced with a nausea-inducing chemical to teach naive quolls that toads are not food, before releasing them into toad-infested country.
The name colobus comes from a Greek word meaning mutilated. Their hands carry only a small tubercle where a thumb would be, turning the hand into a hook that swings through branches quickly, at the cost of a grip that can pinch.