Thrips are tiny insects, typically just a millimetre in length. Some are barely half that size. If that’s how big the adults are, imagine how small a thrips’ egg must be. Now, consider that there are insects that lay their eggs inside the egg of a thrips.
That’s one of them in the image above – the wasp, Megaphragma mymaripenne. It’s pictured next to a Paramecium and an amoeba at the same scale. Even though both these creatures are made up of a single cell, the wasp – complete with eyes, brain, wings, muscles, guts and genitals – is actually smaller. At just 200 micrometres (a fifth of a millimetre), this wasp is the third smallest insect alive* and a miracle of miniaturisation.
A clutch of a dozen turtle eggs lies buried in the bank of Australia’s Murray River. For the embryos inside, timing is everything. In a few days, they will all hatch together, finding safety in numbers in their vulnerable first moments. But such synchrony isn’t easy. To achieve it, the embryonic turtles need to coordinate the pace of their development, keeping in time with one another even before they experience the outside world.
Although all the eggs were laid at the same time, in the same nest, they experience radically different environments. Those at the top of the nest, buried in warmer sun-soaked soil, can be up to six degrees Celsius warmer than those at the bottom. That’s a problem because the embryos develop at different rates depending on how hot they are. Given the gradient of warmth in the nest, the topmost turtles should hatch well before their siblings at the bottom.
That’s not what happens. Ricky-John Spencer from the University of Western Sydney has found that the Murray River turtles can tell whether their clutch-mates are more or less advanced, and shift the pace of their own development accordingly. If their peers are racing ahead, they can play catch-up.
If you saw someone punching a stranger in the street, you might think poorly of them. But if you found out that the stranger had slept with the assailant’s partner, had kicked a kitten, or was Justin Bieber, you might think differently about the situation. You might even applaud the punch-thrower.
When we make moral judgments, we do so subtly and selectively. We recognise that explicitly antisocial acts can seem appropriate in the right circumstances. We know that the enemy of our enemy can be our friend. Now, Kiley Hamlin from the University of British Columbia has shown that this capacity for finer social appraisals dates back to infancy – we develop it somewhere between our fifth and eighth months of life.
Heavy locks, imposing gates and motion-sensing lights can help to fortify your home and safeguard your belongings against thieves. On the other hand, they can also advertise the fact that you have stuff worth stealing. Extra security can be a double-edged sword.
This is as true for plants defending their tissues as it is for humans defending their homes. Maize plants, like many others, protect themselves with poisons. They pump their roots with highly toxic insecticides called BXDs, which deters hungry mandibles. But these toxins don’t come free. The plant needs energy to act as its own pharmacist, so it distributes the poison to the areas that deserve the greatest fortification – its crown roots.
Spider webs are great at catching flying insects, but they’re an inviting target for walking ones. The spider sits pretty in the middle of its home, surrounded by the pre-packaged morsels of the insects it has caught. It’s an all-you-can-eat buffet, and ants should easily be able to raid it. Ants are excellent predators, they hunt in large numbers, and they can negotiate their way along the non-stick parts of the web. And yet, there are very few reports of ants successfully pillaging spider webs. Why?
Shichang Zhang has found one possible answer: some spiders lace their silk with an ant-repelling chemical. Their sticky webs, which so effectively trap some insects, can also deter others.
Many insects suck the juices of plants, much to the dismay of gardeners and farmers. But plants are more than just a source of food; they’re also a source of bugs for bugs. Ayelet Caspi-Fluger from the Newe-Ya’ar Research Center has found that sap-sucking whiteflies can transfer bacteria into the plants they feed from, and these bacteria can then be picked up by other whiteflies. By plunging their straws into the same jug, the whiteflies can pass beneficial microbes to one another.
Insects carry a wide variety of bacteria inside their tissues, which help them digest their food and even grant them superpowers. These passengers are passed on from mother to youngsters, and across sexual partners. But they must also have ways of jumping across the species barrier, for closely related bacteria are often found in distantly related insects. Plants are an obvious route, but until now, no one has clearly shown that they can channel bacteria from one insect to another. Caspi-Fluger is the first.
We now know that birds evolved from small, feathered dinosaurs. It’s easy to think that since birds are still around today, they must have come after their dinosaur* cousins, but that’s not true. In the Cretaceous period, dinosaurs were still around while their descendants flitted through the skies. And some dinosaurs made meals of their flighty relatives. Jingmai O’Connor from the Chinese Academy of Sciences has uncovered the remains of a small dinosaur called Microraptor that has the bones of small bird in its gut.
O’Connor analysed the fossil with Xing Xu, a Chinese scientist who has made a career from discovering beautiful feathered dinosaurs. Microraptor is one of his most important finds. This tiny animal, about the size of a pigeon, had four wings, with long feathers on both of its legs as well as its arms. It was, at the very least, a very competent glider, if not a true flier.
A stickleback is heading for a warm bath. While its peers prefer to swim in lukewarm water at around 16 degrees Celsius, this individual likes it hotter. That’s not because of a personal preference – instead, it is being steered by a parasite. A tapeworm has lodged in its guts, and it needs warmer temperatures to grow as large as possible. The stickleback becomes little more than a living car that drives the worm to the heated pools that it prefers. Read More