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 Drafts and withdrawn editions are never mixed into this index.
The forward-curving plume on a California quail's head looks like a single comma-shaped feather. It is actually a cluster of six separate feathers held together in overlapping formation, larger and blacker in males than in females.
Eryx colubrinus hunts by burying itself with just the top of the head exposed. Its eyes are set high on the skull and face upwards, and a wedge-shaped snout and countersunk lower jaw let it push through sand without taking grains in.
A bleached coral has expelled the algae living in its tissues, which is where its colour and most of its food came from. The animal is alive and white because its skeleton shows through. Whether it survives depends on how long the heat lasts.
Crocodiles north of New Guinea's central mountains nest in the wet season; those to the south nest in the dry. That difference, noticed decades before it was explained, eventually helped justify describing the southern population as a distinct species.
Surgeonfish are named for a hinged, blade-sharp spine on each side of the tail base. In the regal blue tang it lies flat in a groove until the fish flexes, then swings out to slash sideways at a rival or a predator's mouth.
Despite the name, the pygmy hippopotamus is not a small version of the river hippo's life. It is a solitary forest browser that shelters in streams and wallows but feeds on leaves, ferns and fallen fruit under closed canopy.
For two decades the hobo spider was blamed for necrotic wounds in the Pacific Northwest. Later reviews found no verified case in which an identified hobo spider caused one, and health guidance in the United States was revised accordingly.
Observations at heronries in India and the United States describe crocodilians lying still with sticks balanced across the snout during bird nesting season, when birds are collecting nest material. The interpretation as tool use is genuinely contested.
Yellow perch do not scatter eggs or build nests. The female extrudes a single hollow gelatinous ribbon, folded like an accordion and often a metre or more long, which she drapes over submerged branches and vegetation and then abandons.
Embryos of the frilled shark grow at roughly 1.4 centimetres a month, with no seasonal breeding cycle detected. Extrapolating to birth size gives a gestation period estimated at about three and a half years, longer than any other vertebrate yet measured.
The armour that makes a pangolin look reptilian is keratin, the protein of fingernails and rhino horn. That chemistry is also why the scales are traded as medicine, despite offering no more pharmacological value than a trimmed fingernail.
Its skull was so close to a wolf's that anatomists use the pair as a textbook case of convergent evolution. The two lineages had been separate for well over a hundred million years, and the thylacine carried a pouch throughout.
A Bathynomus at a Japanese aquarium stopped eating in 2009 and did not eat again before its death in 2014. The fast was extreme but consistent with an animal built for a seabed where a whale carcass may be the only meal for years.
North Atlantic right whales feed almost entirely on Calanus finmarchicus, a copepod a few millimetres long. Because the whales need dense patches of fat-rich copepods, a shift in copepod distribution can move an entire endangered whale population.
A male village weaver knots a hanging nest from strips of grass and displays beneath it. If the visiting female inspects it and declines, the male frequently destroys the nest himself and builds another in the same place.
Acherontia atropos forces its way into honeybee colonies to drink honey, and when handled it forces air through its pharynx to produce an audible squeak. The two behaviours are linked less closely than folklore claims.
Glass squid bodies are almost entirely see-through, but eyes cannot be transparent and still work. Many species carry photophores beneath the eyes that light the shadow the eye would otherwise cast.
The claim that harvestmen have the most powerful venom of any animal but fangs too short to bite is repeated everywhere. Harvestmen have no venom glands at all, and they are not spiders, so the statement is wrong in both halves.
A hamadryas society stacks: a male with a few females forms a unit, related units form a clan, clans travel together as a band, and bands share a sleeping cliff as a troop of hundreds. Each layer has different membership rules.
Each of the fifteen leg pairs is longer than the one in front of it. The graded arrangement lets the animal move at high speed without its rear legs colliding with its front ones, and the hindmost pair is longer than the entire body.
Satellite tracking in northern Australia showed that these crocodiles do not cross open water by brute effort. They wait for a favourable tide, ride it, and haul out on the bank when the flow turns against them.
White and black rhinos are the same grey. The names distinguish mouth shape, not colour: the white rhino has a wide grazing lip, the black rhino a pointed browsing one, and the two feed in entirely different ways.
Almost every blue animal produces its colour by structure, scattering light with layered crystals. The mandarinfish is one of only two known vertebrate lineages with an actual cyan pigment cell, called a cyanophore.
Mongooses carry a mutation in the receptor that cobra venom targets, blunting its effect. Resistance is partial, not immunity, and in a real fight the animal wins chiefly through speed, thick fur and avoiding being bitten at all.