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 Drafts and withdrawn editions are never mixed into this index.
Amazon floodplain water can approach anoxia for hours at a time. The oscar endures it by suppressing its metabolism sharply and skimming the thin oxygenated film at the surface, surviving severe hypoxia for the best part of a day and complete anoxia for hours.
A reflective layer behind the larger eyes throws light straight back at its source. Held beside the eyes, a torch turns a dark lawn into a field of green points, and surveyors use exactly that to count spiders after dark.
Resting legs on the surface film, the fishing spider reads ripples the way a web spider reads silk. It crosses open water by rowing or galloping, and escapes downward, carrying a film of air trapped in its body hairs.
White-throated sparrows come in white-striped and tan-striped forms, determined by a large inverted chromosome segment. Birds almost always pair with the opposite morph, so mating is organised around four categories rather than two.
The adult hermaphrodite Caenorhabditis elegans has 959 somatic cells, and the lineage of each one from the fertilised egg is known. The count is invariant, which is why the worm became a foundational model organism.
Emperor scorpions are among the heaviest scorpions alive, though not the longest, yet their sting is usually compared to a bee's. Size and danger run in opposite directions across the order: the deadliest scorpions tend to be small, slender-clawed species.
In some northeastern forests, this palm-sized salamander is so numerous that its combined mass exceeds that of all the birds present, and rivals that of the small mammals, despite almost never being seen above the leaf litter.
The devil's coach horse looks wingless: its elytra are short stubs covering almost nothing. Beneath them lie fully functional hindwings, folded through several creases into a package a fraction of their open size.
Before copulating, each snail drives a calcareous dart into its partner's body. The dart carries mucus with hormone-like substances that improve the shooter's chances of fathering offspring, and it is not a Cupid's arrow of courtship.
A feeding bat ray excavates pits in soft sediment by flapping its wings and blowing water, then crushes what it uncovers between pavements of interlocking tooth plates that are continuously replaced from behind.
Deep-sea footage shows Humboldt squid rapidly changing body pattern as they feed in groups. The flickering is backlit by their own glowing photophores, which makes the patterns visible where no sunlight reaches.
Healthy ball pythons routinely stop eating for weeks or months, particularly in the cooler dry season and during breeding. The behaviour alarms keepers, but for a low-metabolism ambush predator it is a normal seasonal adjustment rather than illness.
A rhinoceros horn has no bony core and is not attached to the skull. It is a dense mass of keratin, the same structural protein as hair and fingernails, growing from the skin and capable of regrowing if cut cleanly.
Young zebra sharks are dark with pale vertical bars, which is where the common name comes from. As they grow past about seventy centimetres the stripes break apart into small dark spots on a light background, leaving adults looking nothing like their juveniles.
Every other member of the Tremarctinae, including the enormous Ice Age short-faced bears of the Americas, is extinct. The spectacled bear is the sole survivor of that subfamily and the only bear anywhere in South America.
A common treeshrew leaves her newborns in a separate nest and returns to nurse for a few minutes roughly every 48 hours. Her milk is exceptionally rich, which is what allows an interval that would starve most mammal infants.
An electric eel does not simply stun a fish. Its high-voltage pulses activate the motor neurons of nearby prey directly, causing whole-body muscle contraction, and a doublet of pulses can make a hidden fish twitch and reveal itself.
Pig-nosed turtle embryos finish developing and then stop. They hold in the egg, fully formed, until water reaches the nest. Flooding, or the drop in oxygen it brings, releases the whole clutch to hatch within minutes of one another.
A rock hyrax weighs a few kilograms and looks like a rodent. Its nearest living relatives are elephants and sea cows, and the evidence for that runs through tusk-like incisors, foot anatomy and molecular data.
Described in 2017, Hoolock tianxing takes its scientific name from Chinese characters meaning heaven's movement. Its describers, who are Star Wars enthusiasts, chose Skywalker hoolock gibbon as the English name, and Mark Hamill publicly endorsed it.
With no large protected area available, conservation of this species has rested on municipal ordinances and community sanctuaries in small farming creeks, where villagers agreed to stop killing crocodiles and to leave nesting sites alone.
The female argonaut's papery case is not a home borrowed from another animal. She secretes it herself, and gulps air at the surface then seals it inside to offset her weight at depth.
A female stings a tarantula into permanent paralysis, drags it into a burrow and lays one egg on it. The spider stays alive and fresh for weeks while the larva feeds, leaving the vital organs for last.
The enamel on a beaver's incisors is laced with iron compounds rather than the magnesium found in most mammal enamel. The iron hardens the outer face and gives it a rust colour, and the softer dentine behind it wears away first to keep a chisel edge.