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 Drafts and withdrawn editions are never mixed into this index.
Horseshoe crab blood is blue, copper-based, and clots on contact with bacterial endotoxin. That reaction became the standard test for contamination in vaccines and implants, so hundreds of thousands of crabs are bled each year and returned to the sea.
Newborn hoolocks are pale, close to milky buff. Both sexes then turn black as juveniles. At sexual maturity the females change again, back to a golden buff with dark cheek patches, while males stay black with white brows.
Salamanders are usually described as silent. The lesser siren is a documented exception: handled or disturbed animals produce audible clicks and a yelping sound, and clicking has been recorded between individuals underwater.
A great many genes known to be involved in human disease have a recognisable counterpart in Drosophila melanogaster. That correspondence, together with a ten-day generation time, is why a fly with four chromosome pairs became the workhorse of medical genetics.
Its whole underside is covered in light organs that erase the shark's silhouette against the dim surface. A band of skin under the throat stays dark, and one hypothesis is that this unlit patch mimics a small fish and draws predators into range.
A chicken confronted by a hawk gives a low, drawn-out call; one facing a ground predator gives a rapid, broadband cackle. Flockmates that hear only the recording respond appropriately, looking up or scanning the ground.
In 1987 observers counted around fifteen hundred golden toads at Monteverde breeding pools. The following year eleven appeared. In 1989 a single male was seen, and no golden toad has been recorded since anywhere in the world.
Most grouse switch to seeds or buds when snow arrives. The greater sage-grouse lives through winter on sagebrush leaves alone, a diet loaded with plant toxins, and it lacks the muscular gizzard other gamebirds use to grind hard food.
Most salamanders metamorphose out of the water and lose their gills. The axolotl skips that step entirely, breeding while still wearing the feathery gills of a larva, and it can be pushed through the missing transformation with a hormone injection.
A basilisk crossing a stream is not walking on surface tension. Its foot slaps down, drives a cavity of air into the water, then withdraws before that cavity collapses, so the lizard is pushing against water and air rather than resting on a skin.
Most sharks and rays hold urea in their blood to match seawater. The river stingrays of South America lost that ability along with a working salt-excreting gland, which locked an entire family into fresh water for good.
Rather than waiting for prey to blunder into silk, a bolas spider releases compounds resembling the sex pheromones of female moths, drawing males upwind to within reach of a swinging line tipped with glue.
When seized, the Iberian ribbed newt swings its ribs forward until their sharp tips pierce its own flanks, emerging through glands that coat them in a toxic secretion. The wounds heal, and the newt can repeat the defence.
A dog named Chaser was documented retrieving more than a thousand individually named toys, and inferring the name of a novel object by exclusion. The result says more about training method and testing rigour than about any special canine vocabulary.
At the Cingino dam in Piedmont, ibex work their way across near-vertical masonry more than forty metres high. They are after mineral salts leaching from the stone, and the climb is done mostly by females and young animals.
Through autumn a shrew loses skull height, brain mass and organ mass, then regrows much of it in spring. Named Dehnel's phenomenon, this reversible shrinking cuts the cost of running a body through a season with little food.
Richard Owen described the species in the 1840s from a subfossil skull dug out of a Lincolnshire fen, and it was assumed to be extinct. Living animals were only recognised as the same species after a mass stranding in the Baltic in 1861.
The barrel body and flexible snout read as pig-like, but tapirs are odd-toed ungulates. Their nearest living relatives are rhinoceroses, and after them horses, and the whole order amounts to just three surviving families.
Atlas moths emerge without functional mouthparts and never feed. Everything the adult does, including finding a mate and laying eggs, runs on fat stored during the caterpillar stage, which is why the winged phase lasts barely a fortnight.
Spectacled caimans sold cheaply in the mid-twentieth-century pet trade were released or escaped in southern Florida, and the species established a self-sustaining breeding population there, giving the state a third crocodilian alongside two natives.
The venom activates a specific step in the blood clotting cascade so reliably that a purified fraction is sold to hospital laboratories worldwide, where it is used to detect a clotting disorder in patients who have never been near a snake.
White-nose syndrome is caused by a fungus that grows on hibernating bats at cave temperatures. It does not poison them so much as wake them, and the repeated arousals burn the fat reserve that was meant to last until spring.
The chickadee's alarm call carries graded information. The number of terminal dee notes rises with the threat a predator poses, and small, agile raptors that are genuinely dangerous to a chickadee provoke more dee notes than large ones that are not.
Playing back a recorded kea warble caused nearby wild birds to begin playing, often with no partner and no prior play under way. It is the first non-mammal shown to have a contagious, emotionally positive play call.