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 Drafts and withdrawn editions are never mixed into this index.
Most Roesel's bush-crickets have wings too short to fly. When density is high or conditions favour dispersal, a proportion develop into a long-winged form capable of flight, and this macropterous form has driven the species' rapid range expansion.
Threatened, a giant whip scorpion swivels its abdomen and fires a fine mist from glands at the tail base. The spray is roughly five-sixths acetic acid, the same compound that makes vinegar sour, and it can be aimed with considerable accuracy.
The quills detach on contact, not in flight. Each one is loosely rooted and barbed at the tip, so a slap of the tail plants dozens into an attacker, and the microscopic barbs make them far harder to pull out than to push in.
The two coloured spirals are crowns of feathery radioles that filter plankton from the water and exchange gas. Almost all of the animal is hidden inside a calcareous tube bored into a living coral head.
Notonecta glauca spends its life inverted beneath the surface film, rowing with hair-fringed hind legs. Its eyes look downwards through the water, its dark side faces the sky, and it carries a silver air store on what is anatomically its back.
Wild gorilla tool use went undocumented far longer than in chimpanzees or orangutans. The first published record came in 2005, when a female at a forest clearing in the Republic of the Congo picked up a branch and probed the water ahead of her before wading in.
On meeting a strong new smell or taste, a hedgehog will chew the source into foam and then contort to spread that saliva across its spines. The behaviour is called self-anointing and no one has established what it is for.
Whales in the Gulf of Mexico were assumed to be a population of Bryde's whale until genetic and skull evidence separated them. Rice's whale was named in 2021, immediately becoming one of the rarest large animals on Earth.
Commercial sealing reduced the species to perhaps a few dozen animals on one Mexican island by the 1890s. The population has since rebounded into the hundreds of thousands, but the genetic diversity lost in that squeeze has not returned.
Photographic sequences analysed in 2013 showed Todarodes pacificus leaving the water under jet power, then spreading its fins and arm membranes into aerofoils and gliding for tens of metres above the surface before folding them and re-entering.
Rival males draw their tails across scent glands on the wrists and shoulders, then arch the loaded tail over the back and flick the scent towards an opponent. The exchange can run for nearly an hour and usually settles the dispute without contact.
A black ocellus sits on the rear dorsal fin while a dark band masks the real eye. The arrangement is widely read as redirecting a predator's strike away from the head, though the evidence is more mixed than the textbook version suggests.
The familiar call is a duet. The sharp kewick comes from one bird, usually the female, and the quavering hoooo from another, usually the male, so a single tawny owl never produces the whole phrase alone.
Large rat snakes ascend vertical, limbless trunks by folding the body into a series of horizontal loops and gripping the bark from opposite sides. The technique, called concertina climbing, is slow and metabolically expensive.
At the base of its hind legs, the nymph of Issus coleoptratus carries two curved strips of interlocking teeth that mesh like gear wheels. They force both legs to extend together during a jump, within a window far shorter than a nerve signal could manage.
American badgers and coyotes have repeatedly been observed foraging as pairs. The badger can dig a rodent out; the coyote can chase one that bolts. Together they close both escape routes, and both catch more.
Cut a hydra into pieces and each sufficiently large piece regrows a complete animal, head and foot correctly placed. Even dissociated cells, reduced to a suspension and left to reaggregate, can reorganise into a functioning hydra.
A hatchling leopard tortoise is crisply marked, each scute carrying sharp black blotches on pale yellow. Those markings blur and darken as the animal grows, and a large old adult can be almost uniformly brown, with the pattern that named it barely readable.
The red coral of Mediterranean jewellery is an octocoral with eight-tentacled polyps and a solid calcite core. It hosts no photosynthetic algae, grows in the dark under overhangs, and adds well under a millimetre of branch length in a year.
In autumn, Caribbean spiny lobsters form marching lines of up to sixty animals, each keeping contact with the one ahead using its antennae. The formation reduces drag and appears to make the group harder for predators to attack.
This skua breeds farther south than almost any other bird, and individuals have been seen at the geographic South Pole itself, hundreds of kilometres from open water and from any possible food source, apparently while ranging over the ice sheet.
The European green crab has spread to five continents without any specialist trick. It survives brackish water, air exposure, near-freezing and warm temperatures, and long journeys in ballast tanks, and it eats almost anything it can crush.
Nearly all gibbons advertise their territory with a coordinated duet between mated partners. On Java, the silvery gibbon does not. Females deliver an elaborate great call alone, and males sing separately, without weaving their voices together.
In the western Amazon, macaws and other parrots congregate at exposed clay banks and eat soil. The long-favoured explanation was detoxification of poisonous seeds, but the best-supported reading now centres on sodium, which is scarce far inland.