This is the sixth of a series of reviews, looking back at a year of science according to topic and theme. This one is pretty self-explanatory. These aren’t necessarily the most entertaining videos of the last year, but they all helped illustrate an already fascinating story.
10) Pocket Science – belly-flopping frogs
One of the more amusing videos of the year (and I take credit for adding an appropriate score). Frogs are powerful jumpers and most land gracefully on their front legs. But not the Rocky Mountain tailed frog. It belongs to a lineage of ancient frogs that lands with an awkward mix of belly-flops, face-plants and lengthy skids. Only when it grinds to a halt does it recover its outstretched limbs together. These results support the idea that frogs evolved their jumping abilities to escape from danger by rapidly diving into water. Only later did they evolve to pull their legs in earlier and land gracefully on land. The Rocky Mountain tailed frog never did, but it compensates with a large shield-shaped piece of cartilage that protects its undersides.
9)Pocket science – bursting bubbles make more bubbles
A bursting bubble might seem unspectacular but a set of slow-motion videos revealed more to this everyday even than meets the eye. The videos showed that a popped bubble doesn’t just vanish. Instead, it gives birth to a ring of smaller daughter bubbles, each of which can produce an even smaller ring when it bursts.The whole process takes place in a few thousandths of a second and it can only happen twice before the daughter bubbles get too small.
8 ) Snake versus snail
Want to see a snake de-shell a snail in ten seconds? Of course you do. Iwasaki’s snail-eating snake grabs snails by the shell with its upper jaw and sticks its lower one into the opening. Both sides of the lower jaw can move independently, and by shifting them back and forth in turn, the snake slowly ratchets the snail out of its fortress. This works for most snails, whose shells sit on their right side and spiral clockwise. But some mutants have a mirror-image shell that foils the snake. Not only that, but the reversed shell prevents these mutants from mating with their clockwise kin, possibly splitting the snail population into two separate species.
7) How chimpanzees deal with death and dying
On the 7th of December, 2008, a chimpanzee called Pansy died peacefully. Her final moments were caught on film, including the actions of her fellow chimps. The others seem to care for Pansy in her final minutes, examine her body for signs of life, and avoid the place where she died. Her daughter, Rosie, even conducted the equivalent of an all-night vigil. The video is a rare and beautiful glimpse into how one of our closest relatives copes with death.
6) Caterpillars must walk before they can anally scrape
The masked birch caterpillar defends its territory by scraping its jaws and anus across a leaf to create a complex scratching noise. The bizarre “anal scraping” is based on the same walking movements that their ancestors used to chase after rivals. The other parts of their signalling repertoire – drumming and scraping jaws – are ritualised versions of fighting moves like biting, butting and hitting. While their earlier cousins might resort to such fisticuffs, the anal-scrapers conduct their rivalries with all the restraint of Victorian gentlemen.
5) Tree frogs shake their bums to send threatening vibes
Male red-eyed tree frogs prefer not to fight. Instead, they duel by vigorously shaking their bums at each other. Their quivering buttocks shake the plants they sit on, sending threatening vibrations towards their rival. This secret line of communication reveals the strength and size of the competitors, and they’re the last line of negotiation before battle commences.
4) Suicidal menopausal aphids save their colony by sticking themselves to predators
These social aphids live inside a swollen structure – a gall – on a witch hazel plant. When it’s threatened (in this case, by a needle), it exudes a waxy liquid from its body that quickly solidifies and sticks it to the threat. It’s a suicidal defence – when used against a predator like a ladybird, the wax stops the hunter from walking or biting, but the aphids die with it. Only ‘menopausal’ aphids do this. They can’t reproduce any more and their final role is to defend their relatives, with their lives if necessary.
3) Ambush ants capture giant prey using Velcro principles
Insects landing on a Cecropia obtusa plant are in for a nightmarish surprise. Underneath the leaves, thousands of Azteca andreae ants lie in ambush, poised at the edges with their jaws outstretched. As soon as the insect lands, the ants rush out from their hiding places, seize it by the legs and pull it spread-eagled. The leaf turns into a medieval torture rack, and the ants bite, sting and dismember the immobilised victim.The ants’ claws hook onto tangled hairs on the plant’s leaves, allowing them to hold a struggling insect that outweighs them by 10,000 times. Evolving together, the ants and the plant have developed a type of biological Velcro.
2) The strumming assassin that hunts spiders on their own webs
Witness an assassin bug luring a spider to its doom with bad vibes. Sitting on the web, the bug plucks the silken threads with its legs, mimicking the frequency of weakly struggling prey. These deceptive vibrations are an irresistible draw to the spider, who rushes towards the bug, only to have stiletto-like mouthparts jammed through its head. The build-up is fantastic but for the impatient among you, the money shot happens at 1:09.
1) Sperm races in a fly’s genitals
This is a live broadcast of a sperm race. Mollie Manier engineered male fruit flies to produce sperm that glowed either red or green. By following these glows with a special microscope, she managed to film the sperm racing around female’s genital tract at high speed. In the animal kingdom, such sperm competition is rife, but Manier’s glowing sperm makes it evident like never before. Particularly if you add music to it…