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 Drafts and withdrawn editions are never mixed into this index.
This large nudibranch escapes by unfurling its mantle and undulating through open water. It also transfers defensive compounds obtained from its sponge prey into its egg ribbons, so the eggs are chemically protected before they hatch.
Despite the name and the long pale body, Teredo navalis is a bivalve mollusc. Its two shells are no longer armour but rasping tools at the head of the burrow, and bacteria in a special organ help it digest the wood it drills.
Sipunculans feed by extending a slender introvert with a tentacle ring at the tip, then retracting it entirely into the trunk by muscular pull. Withdrawn, the animal is a smooth sac with no visible head.
Under stress or injury, the adult medusa can reverse its life cycle and settle back into a polyp, then bud new medusae. That escapes ageing, not predation or disease, and in the sea most individuals die long before the trick becomes relevant.
Kirtland's warbler nests only under jack pines roughly five to twenty years old, where the lower branches still touch the ground. Fire suppression removed that habitat, and the species now depends on deliberate harvest and replanting to recreate it.
No ant directs the colony. A waiting forager leaves the nest only after enough returning foragers brush antennae with her at a high enough rate, so the outflow of ants tracks the rate of successful returns.
No mammal weans faster. A hooded seal pup nurses for about three to five days on milk of extreme fat content, roughly doubling its mass, and is then left on the ice while the mother departs to mate.
Like humans and unlike most mammals, guinea pigs have lost the enzyme that completes vitamin C synthesis. They must eat it or develop scurvy, and that shared defect is why they became the standard laboratory animal for nutrition research.
The spray is not a random defensive squirt. High-speed video shows spitting cobras track a face, discharge in a rotating pattern and time the release to head movement, so venom lands across both eyes rather than on skin.
During an underwater somersaulting embrace the eggs are pressed into the female's back, where skin grows over them. Weeks later small toads push out through her skin, having skipped the free-swimming tadpole stage entirely.
Female superb fairywrens call repeatedly to their eggs during incubation. Chicks hatch producing a begging call that contains a distinctive element from that call, and parents feed nestlings that reproduce it.
Adult male gharials develop a bulbous cartilaginous structure over the nostrils, the ghara, which no other living crocodilian possesses. It appears to act as a resonator, altering the buzzing call the male makes during courtship display.
DNA recovered from glyptodont shell material places the group inside the armadillo family tree rather than beside it. The animals were armadillos that grew to over a tonne and fused their armour bands into a single rigid dome.
Cut a planarian in pieces and each fragment can regrow a complete worm, head included. The capacity comes from a large population of adult stem cells called neoblasts, the only dividing cells in the animal.
Manta rays sit inside the stingray order, yet the barbed tail weapon that defines their relatives has dwindled to nothing useful. What remains near the base of the tail is a hardened lump rather than a serrated, venom-grooved spine.
A wandering albatross chick takes so long to fledge that its parents cannot start again the following season. Successful pairs skip a year, which makes each adult death far more costly to the population than the raw numbers suggest.
Researchers revisited a single female on a Monterey Canyon rock face 18 times over 53 months. She never left, was never seen feeding, and her eggs hatched at the end of the longest brood on record.
A rat's diaphragm and stomach anatomy make the reflex impossible, and it lacks the brainstem coordination for the act. This is why rats sample unfamiliar food in tiny amounts first, and why bait shyness is so hard for pest controllers to overcome.
Soft-shell crab is not a species. It is an ordinary blue crab harvested in the few hours after it sheds its old shell, before the new one hardens, a window that watermen predict by reading coloured lines on the swimming paddles.
Unlike the giant squid, which grips with toothed sucker rings, the colossal squid bears sharp hooks. Two rows on each tentacle club rotate on a short stalk; the hooks along the eight arms are fixed and do not swivel.
Pressed by a predator, a mule deer stots: it launches off all four feet at once and lands on all four, bounding across broken ground. It is slower than a flat run, which is what makes the behaviour interesting.
Bites from the lone star tick can sensitise people to galactose-alpha-1,3-galactose, a sugar present in the tissue of most non-primate mammals. The result is a delayed allergic reaction to beef, pork and lamb, arriving hours after the meal rather than minutes.
Almost all sharks are locked into the sea by their body chemistry. The bull shark is the exception that swims up rivers, and it does so by adjusting its kidneys, gills and rectal gland to dump the salt it would otherwise need to retain.
Despite being a crab that lives on tropical shorelines, an adult Birgus latro cannot breathe underwater. It has traded functioning gills for a pair of air-breathing organs, and prolonged immersion will kill it, even though its larvae are entirely marine.