Panama’s San Lorenzo forest reserve is around the size of Manhattan. For two years, this small area was host to 102 scientists, working together to count everything that crept and crawled. They came from 17 countries, and converged upon a half-hectare of the forest, about the size of half a rugby pitch. They dug into the soil, and ascended into the 40-metre-tall treetops with ropes, balloons, and a giant crane. They unleashed fogs, set up sticky traps, and hacked into pieces of wood.
Together, they were part of the largest ever systematic attempt to answer a disarmingly simple question: in a patch of tropical rainforest, how many species of insects and other arthropods are there?
After collecting the critters in 2003 and 2004, and analysing the material for eight years, they got an answer: 6,144 species in that patch of forest. Using computer simulations to scale that up, they estimate that the entire 6,000-hectare Manhattan-sized forest is home to around 25,000 arthropod species.
A very hungry caterpillar munches on a cabbage leaf and sets off an alarm. The plant releases chemicals into the air, signalling that it is under attack. This alarm is intercepted by a wasp, which stings the caterpillar and implants it with eggs. When they hatch, the larval wasps devour their host from the inside, eventually bursting out to spin cocoons and transform into adults. The cabbage (and those around it) are saved, and the wasp—known as a parasitoid because of its fatal body-snatching habits—raises the next generation.
But that’s not the whole story.
Some parasitic wasps are “hyperparasitoids”—they target other parasitoid wasps. And they also track the cabbage’s alarm chemicals, so they can find infected caterpillars. When they do, they lay their eggs on any wasp grubs or pupae that they find. Their young devour the young of the other would-be parasites, in a tiered stack of body-snatching. It’s like a cross between the films Alien and Inception.
If you want to find an ocean animal that kills with speed, don’t look to sharks, swordfishes, or barracuda. Instead, try to find a mantis shrimp. These pugilistic relatives of crabs and lobsters attack other animals by rapidly unfurling a pair of arms held under their heads. One group of them—the smashers—have arms that end in heavily reinforced clubs, which can lash out with a top speed of 23 metres per second (50 miles per hour), and hit like a rifle bullet. These powerful hammers can shatter aquarium glass and crab shells alike.
Most research on mantis shrimps focuses on smashers, but these pugilists are in the minority. The majority are “spearers”, whose arms end in a row of fiendish spikes, rather than hard clubs. While the smashers actively search for prey to beat into submission, the spearers are ambush-hunters. They hide in burrows and wait to impale passing victims. They’re Loki to the smashers’ Thor.
Given their differing lifestyles, you might expect the spearers to be faster than the smashers. They rely on quick strikes to kill their prey, and they target fast victims like fish and shrimp rather than the tank-like, slow-moving crabs favoured by smashers. But surprisingly, Maya DeVries from the University of California, Berkeley, found that the fastest spearer strikes at just a quarter of the speed of the fastest smasher.
Absence can speak volumes. The lack of sediment in a flat piece of ground—a track—can testify to the footstep of a dinosaur that once walked on it. The lack of minerals in a solid shell—a hole—can reveal the presence of parasite that was once trapped in it. The world’s museums are full of such “trace fossils”, but so are many of the world’s art galleries.
The image above is taken from a woodcut currently residing in Amsterdam’s Rijksmuseum. It was made by etching a pattern into a block of wood, so that the remaining raised edges could be dipped in ink and used to print an image. These woodcuts were the main way of illustrating European books between the 15th and 19th centuries, and were used for at least 7 million different titles.
But as you can see, the print is l