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 Drafts and withdrawn editions are never mixed into this index.
A female giant Pacific octopus lays tens of thousands of eggs, then stops eating and spends months fanning and cleaning them. She dies around the time they hatch, in a pattern biologists call semelparity.
Coelacanths are lobe-finned fishes, not ray-finned ones, and were described from fossils and thought to have ended with the Cretaceous, until a living one was pulled from a trawl catch off South Africa in 1938 and recognised by a museum curator.
Born on drifting ice that may not last, a harp seal pup nurses on milk of extraordinary fat content, roughly triples its birth mass in under two weeks, and is then abandoned to live on that stored blubber while it learns to swim.
The Sargasso Sea spawning ground was inferred a century ago from the sizes of drifting larvae, not from seeing eggs laid. Satellite tagging has now tracked adults toward the area, but a wild European eel spawning has still never been directly observed.
Each right whale carries a unique arrangement of rough skin patches on its head. The patches look white because they are colonised by pale crustaceans, and the resulting pattern lets researchers recognise individual whales for their entire lives.
Surimi, the pale paste behind imitation crab sticks, is usually made from Alaska pollock. The fish is washed repeatedly until almost everything but the myofibrillar protein is gone, then reset into a springy gel and flavoured.
Sequenced in 2014 as the first cartilaginous fish genome, it changes more slowly than any other vertebrate genome examined. It also turned out to be missing the gene family that other vertebrates use to build bone.
A raven that has been observed caching food frequently returns and moves it. In experiments it adjusted its behaviour to the presence of a peephole and the sound of another raven, even with no bird visible.
Lake sturgeon are among the longest-lived freshwater fishes in North America. Females have been aged past 100 years, and because they do not spawn every year a single fish may reproduce only a few dozen times in a century-long life.
A twenty-year-old Pacific halibut today weighs considerably less than a twenty-year-old did in the 1980s. The decline in size-at-age is well documented across decades of survey data, and its cause remains genuinely unsettled.
A beetle roughly a centimetre long has killed ash trees across a continent. The damage is not from feeding volume but from position: larval galleries in the phloem sever the tree's route for moving sugars downwards.
As cane toads spread west across northern Australia, populations of freshwater crocodiles in some river systems fell sharply. The crocodiles die from the toad's bufotoxin after swallowing an animal they have no evolutionary reason to avoid.
The smallest bear in the world carries a tongue that can extend around 20 to 25 centimetres. It is a probe for extracting honey and insect larvae from cavities that the bear's claws have already opened.
Sacculina is a barnacle that has given up its shell, gut and limbs to live inside a crab. It sterilises the host, and in males it reshapes the body and behaviour until the crab tends the parasite's brood as if it were its own.
The male bed bug does not use the female's reproductive opening. He drives a sharpened organ straight through her abdominal wall and injects sperm into the body cavity, from which it migrates to the ovaries. The female has evolved armour at the target site.
A covey of northern bobwhites roosts on the ground in a tight disc, tails together at the centre and heads pointing out. The formation conserves heat on cold nights and means the group can explode outward in every direction at once.
Despite its name, Vampyroteuthis does not hunt. It trails long filaments to collect marine snow, the drifting mix of dead plankton, faecal pellets and mucus that sinks from the sunlit ocean above.
As many as sixty or seventy-five hairs sprout from a single follicle, giving fur so tightly packed that water cannot readily drain out of it. A soaked chinchilla stays damp long enough for fungal skin infections to take hold, which is why captive animals bathe in volcanic dust instead.
A song sparrow from the Aleutian Islands can be nearly twice the mass of one from the American southwest and much darker. The species carries a long list of described subspecies, making it a standard example of geographic variation within one bird.
For decades the Mediterranean was thought to hold an endemic devil ray while a near-identical species ranged the rest of the world. A 2017 reassessment found no consistent difference between them, and the supposed endemic became a global animal.
Male ricinuleids transfer sperm not with their pedipalps, as spiders do, but with a specialised structure on the third pair of walking legs. The order also carries a hinged hood, the cucullus, that swings down to cover the mouthparts.
The sharp squeak at the bottom of a male Anna's hummingbird's courtship dive is not vocal. Wind-tunnel work showed it is produced by the outer tail feathers fluttering as the tail is spread for a few milliseconds at high speed.
Gentoos are routinely credited with underwater speeds around 36 kilometres per hour. The figure is a burst, not a cruise: gentoos travel far more slowly on ordinary foraging trips, and the record reflects a short dash rather than sustained swimming.
The sunbeam snake's scales throw off a metallic rainbow sheen stronger than any other snake's. It is also almost entirely fossorial and nocturnal, so the sheen is rarely visible to anything in its own environment.