Did you know that trout fake orgasms, or that frogs swallow with their eyes? Matt Walker scours the latest zoological research to find the interesting facts
Published: 04 October 2006
SEX BY SURROGATE
A male flour beetle (Tribolium castaneum) can mate and impregnate a female he has never met. No other animal is known to have sex by proxy in this way. Many males often mate with each female. The first male will deposit sperm in the female, then a second will arrive and use its spiny genitalia to scrape out his competitor’s sperm, before mating itself. Much of the sperm of the first male is carried unwittingly by the second male on its genitalia. One in eight females are fertilised by proxy.
HOW WAS THAT FOR YOU?
Female brown trout (Salmo trutta) fake orgasms to encourage males to ejaculate prematurely. By doing so, they dupe their partner into thinking it has successfully mated, before the female fish moves on to find a better male with which to do the real thing.
MONKEYS MIX THEIR DRINKS
Given the choice of whether to have an alcoholic beverage, or something alcohol free, around in one in 20 vervet monkeys (Cercopithecus aethiops) become instant binge drinkers, gulping down so much booze that they eventually pass out. Around one in seven are heavy drinkers who like their spirits neat, while most are moderate drinkers who prefer to wash down their alcohol with a little fruit juice. Just one in seven decide not to drink at all.
BACH IS BEST
Java sparrows (Padda oryzivora) appear to prefer the music of some composers. Sparrows will listen longer to music by Bach than by Schoenberg, and prefer Vivaldi to Elliott Carter.
MAKE ME CRY
There are moths that drink the tears of elephants. Tears contain salt, water and trace levels of protein. Mabra elephantophila steals the tears without the elephants seeming to notice. Lobocraspis griseifusa does not wait for an animal’s eyes to moisten – it sweeps its proboscis across the eye of its host, irritating the eyeball, encouraging it to produce tears.
GIVE ME BLOOD, AND MAKE IT FRESH
Dracula ants (Adetomyrma venatrix) suck the blood of their young. Queen Dracula ants live in Madagascar, cut holes in their own larvae and feed upon the haemolymph, or insect blood, that oozes out.
TASTED GOOD, I THINK
The star-nosed mole (Condylura cristata) is the fastest-eating mammal in the world, capable of wolfing down a snack of worms in 227 milliseconds. It uses 22 pink fleshy tentacles that adorn its face, each highly sensitive to touch.
DON’T SWIM AND EAT
European eels (Anguilla anguilla) will not eat at all during their long migration to the Sargasso Sea.
A female hippopotamus (Hippopotamus amphibious) can eat more food relative to its body size than any other ruminant. Its stomach contents can make up one quarter of its total body weight.
THAT FLOATING FEELING
Seals hold their breath while sleeping on the surface of the water.
SHOOT ME, SEE IF I CARE
Tardigrades, eight-legged animals that are nicknamed water bears, are the hardiest creatures on earth. The tiny organisms, up to 1.2mm long, are capable of withstanding the most extreme environments by dehydrating and going into a state of frozen animation. There is anecdotal evidence that some can survive being immersed in liquid helium, just 1C above absolute zero. They can withstand being boiled in water, thrown into pure alcohol, and a pressure of 600 mega-pascals (six times the pressure of sea-water at a depth of 10,000 metres).
One species of spider spends its life underwater. Using a dense mat of specialised hairs that covers its body and abdomen, the water spider (Argyroneta aquatica) traps a bubble of air around its body, breathing the trapped air.
WHO NEEDS SATNAV?
Wandering albatrosses (Diomedea exulans) can pinpoint the specific remote island where their nests are located after making foraging flights of several thousand kilometres of featureless ocean. They do not rely on the earth’s magnetic field, and no one knows how the birds acquire such precise and impressive navigation ability.
The cookie-cutter shark (Isistius brasiliensis) measures only 50cm in length, yet has been recorded taking chunks out of the rubber sonar domes of nuclear submarines with its razor-sharp teeth.
HONEY, THEY TOOK THE KIDS
Adult emperor penguins (Aptenodytes forsteri) attempt to kidnap the chicks of another breeding pair. They forcibly wrestle the juvenile away from its parents, who try to protect the chick by fighting back. Kidnapping often occurs when a penguin that has failed to breed sees a chick begging its parents to be fed, and interprets the juvenile’s behaviour as a cue to parent it.
A female house sparrow (Passer domesticus) will often seek out the nest of another female that her partner has also mated with. She will then kill the first female’s young, to remove the competition and ensure that the male spends as much time as possible helping to raise her chicks.
The caterpillar of the large blue butterfly settles beneath its food plant to await discovery by red ants (Myrmica species). By secreting hydrocarbons that mimic those made by Myrmica, the caterpillar tricks a foraging worker into taking it into the nest, where it is placed among the ant grubs. The caterpillar then moves to safer chambers, returning periodically to binge-feed on ant grubs.
SLAVERY ON SIX LEGS
Some ant species make slaves of others. Those in the subfamily Formicinae will go out and raid the nests of other species nearby, and steal their eggs and pupae. These are taken home, when the resulting young are raised as slaves, having to do all the foraging, cleaning and babysitting for their masters.
TIME TO BALE OUT
Certain species of canopy ant jump out of trees to escape being eaten. When Cephalotes atratus is approached by a predator it throws itself into the air, orientating its body to steer into a steep glide and head for the lower reaches of the tree trunk. On average, 85 per cent of all ants that take a leap successfully land back on the tree.
Mussels can be voracious cannibals. At certain times of the year, up to 70 per cent of all food eaten by the green-lipped mussel (Perna canaliculus) is the larvae of its own species.
TRY THIS ON FOR SIZE
Uloboridae spiders wrap their victims to death. An individual small uloborid spider (Philoponella vicina) will weave more than 140 metres of silk to wrap a moth or beetle. It binds the silk shroud so tight that it compresses the prey’s body, breaking the insect’s legs, buckling its compound eyes inwards, and often killing it outright. Spiders of the family Uloboridae have lost their fangs, forcing them to evolve their vice-like death shroud.
In the UK alone, domestic cats kill 57 million mammals a year, 27 million birds and 5 million reptiles and amphibians.
STOP AND YOU DIE
Swarms of Mormon crickets (Anabrus simplex), which in the United States reach up to 10km long, keep on the move not just to find food, but to avoid being eaten by each other. If an individual stops for any reason, it is likely to be devoured by some of the millions of its following brethren.
THE HOUDINI CHALLENGE
The parasitic gordian worm (Paragordius tricuspidatus) begins its life in water before infecting the body of a larger insect host: a cricket. But the worm has a remarkable ability to survive even if its host is eaten by a larger predator. When the cricket is eaten, and partially digested, the worm escapes by burrowing through the body of the predator, usually a fish or amphibian, until it emerges unscathed in the water, where it continues its life cycle.
WOULD YOU LIKE EYES WITH THAT?
Animals usually swallow using their tongue and throat. The northern leopard frog (Rana pipiens) uses its eyes. To swallow food such as a small cricket, it closes its eyes and retracts its eyeball into its body. These push into the pharynx and against the prey item, and regular retractions help force the food to the back of the oesophagus.
THE BIG CELL
The yolk in an unfertilised ostrich’s egg is the largest single cell found in nature.
WE’RE JUST DOWNSIZING
The Galapagos marine iguana (Amblyrhynchus cristatus), the only sea-going lizard, is also the only vertebrate known to shrink in body size regularly when adult, and then to grow larger again. The iguanas shrink up to 15 per cent in body length during El Niño weather events, losing bone mass. The following year the iguanas grow even larger before shrinking again.
SEEING IS BELIEVING?
Tarsiers, a primitive group of primates, have eyeballs bigger than their brains.
CAN’T HELP THE WAY WE FEEL…
Some genetically engineered mice have have hearts that glow green every time they beat.
The wood frog (Rana sylvatica) freezes solid during the winter before thawing out as the temperature rises in spring. The frog has a unique physiology that prevents damaging ice crystals forming within its cells.
COME FLY WITH ME
The elusive paradise tree snake (Chrysopelea species) is the only vertebrate that can fly – despite having no limbs. The snake is a true glider, defined as covering a greater horizontal distance than it falls vertically. First the tree snake leaps from a tree into the air, and adopts an S-shape, changing its body shape to that of a biplane. Then the snake undulates its body, and while no one can be sure why it does this, the changing posture might serve to move its centres of gravity and the flow of air pressure in a way that allows controllable flight. It can achieve a glide angle of just 13 per cent to the horizontal (90 per cent constituting free fall) and cover distances of 20 metres.
WHALE OF A TIME FOR BABIES
For the first month of their lives, newborn killer whales (Orcinus orca) and bottlenose dolphins (Tursiops truncatus) do not sleep but remain mobile for 24 hours a day – as do their mothers.
EAT ME, BABY
A worm-like amphibian, the caecilian (Boulengerula taitanus) takes parenting to a new level. By elongating specialised stratified epithelial cells, mothers transform their skin until it is twice as thick, and it is then eaten by their offspring.
PETER PAN SYNDROME?
Many tadpoles of the African clawed frog (Xenopus laevis) never turn into frogs, instead growing into giant, grossly deformed tadpoles with a hunchback, on average four times longer and up to 50 times more massive than normal tadpoles. They can survive for years, although they cannot reproduce.
CATCH US IF YOU CAN
Cuttlefish (Sepia officinalis) change colour almost instantaneously to mimic the rock or seaweed of the seafloor against which they are hiding. They do so while being completely colour-blind.
HOME IS BEST
In 25 years of intensive research watching a group of killer whales (Orcinus orca) in the coastal waters of the north-eastern Pacific Ocean, there has not been one documented incidence of a male or female offspring leaving their mother. Each baby grows up and remains within the family group for the rest of their lives.
CAN’T SWIM? NO PROBLEM
Fire ants (Solenopsis invicta) survive floods by clinging together in huge numbers to form large rafts.
Moths that Drink Elephants’ Tears and Other Zoological Curiosities, by Matt Walker, is published by Portrait, £9.99. To order a copy with free p&p, call Independent Books Direct on 08700 798 897