Why can’t penguins fly?

Even the very smallest penguin,the fairy penguin,weighs 1 kg,which is about as much as a herring gull (银鸥). But herring gulls have a 1.4-meterwingspan,compared with just 32 centimeters for the fairy penguin. Water is 784 times denser (密度较大的) than air,and around 62 million years ago,penguins began making adaptations for swimming underwater. Their bones are filled with heavy bone marrow (骨髓)rather than air and they have much larger stomachs for making long fishing trips away from the nest.

How do squirrels find buried nuts?

It was once thought that they just used their noses to sniff out buried nuts and that the majority were never actually located. But a study at Princeton University showed that squirrels actually have a good memory and can build a map of the route from one hidden nut to the next.

Why don’t horses have toes?

Early horses such as Hyracotherium, which lived 55 million years ago, did have toes, but they were much smaller animals. For taller animals, extra weight at the end of their legs has a much bigger influence on their speed. A recent study at Harvard University, the USA, found that one broad hoof (蹄) is almost as strong as many smaller toes, but much lighter.

Do animals have blood types?

Yes, they do! As long as the animals in question have blood (not all do)then they will have species-specific “blood groups”. As with humans, these groups are determined by the structure of the blood based on the presence or absence of antibodies along with the make-up of the proteins that sit on the outside of red blood cells.

Humans are usually one of four main blood types. Thirteen types have been identified for dogs, eight for horses and three for cats.

The tomato leafminer moth originates from Peru and is common throughout South America. However, it has spread through Europe since 2007 and has become one of the largest pests in Mediterranean regions, threatening food supplies. Experts around the world are currently struggling with new ways to battle the moth, but it has developed resistance to pesticides (杀虫剂), leaving farmers helpless to stop the damage. Now a new study from the University of Portsmouth has shown that an answer may lie in the tropical tent-web spider.

Scientists carried out laboratory tests and found that the spiders banded together to form webs which easily caught the flying insects, which they then ate. The tropical tent-web spider operate in large groups and can create giant joined-up webs to capture bugs. Dr. Lena Grinsted, the lead author of the study, said, “Spiders can provide large surface areas of capture webs capable of catching insects in the air. This could potentially lead to a reduction of reliance on chemical pesticides, resulting in less pollution in soils, waterways and food chains in the future.”

Crop damage is also caused by the larvae (幼虫), which directly attack the tomato fruit, making the crop ugly and thus unmarketable. Larvae live inside the leaf until they begin the process of turning into a moth, making them difficult to control. However, scientists expect that by targeting the adult moth population, it will reduce the number of eggs being laid. In addition, the spiders build the biggest webs during the summer months, which will benefit the tomato planting and growing season in May and June.

The researchers said the study will “open doors for the use of group-living spiders to control agricultural pests”, but warned that more work was needed to check the spiders did not change the ecology of regions. Dr. Grinsted added, “Future studies are now needed to investigate whether the spiders may negatively impact crop pollination (授粉) by also catching bees and other key pollinators.”

Since English biologist Charles Darwin (1809 –1882) published On the Origin of Species in 1859, scientists have vastly improved their knowledge of natural history. However, a lot of information is still the subject of speculation, and scientists can still only make educated guesses at certain things.

One subject that they guess about is why some 400 million years ago, animals in the sea developed limbs (肢) that allowed them to move onto and live on land.

Recently, an idea that occurred to the US paleontologist (古生物学家) Alfred Romer a century ago became a hot topic once again.

Romer thought that tidal (潮汐的) pools might have led to fish gaining limbs. Sea animals would have been forced into these pools by strong tides. Then, they would have been made either to adapt to their new environment close to land or die. The fittest among them grew to accomplish the transition (过渡) from sea to land. Romer thought that tidal pools might have led to fish gaining limbs.

Romer called these earliest four-footed animals “tetrapods” (四足动物). Science has always thought that this was a credible theory, but only recently has there been strong enough evidence to support it.

Hannah Byrne is an oceanographer (海洋学家) at Uppsala University in Sweden. She announced at the 2018 Ocean Sciences Meeting in Oregon, US, on Feb 15 that by using computer software, her team had managed to link Romer’s theory to places where fossil deposits (化石沉积) of the earliest tetrapods were found.

According to the magazine Science, in 2014, Steven Balbus, a scientist at the University of Oxford in the UK, calculated that 400 million years ago, when the move from land to sea was achieved, tides were stronger than they are today. This is because the planet was 10 percent closer to the moon than it is now.

The creatures stranded in the pools would have been under the pressure of “survival of the fittest”, explained the UK’s University of Bangor ocean scientist Mattias Green. As he told Science: “After a few days in these pools, you become food or you run out of food … the fish that had large limbs had an advantage because they could flip (空翻) themselves back in the water”.

As is often the case, however, there are others who find the theory less convincing. Cambridge University paleontologist Jennifer Clark, speaking to Nature magazine, seemed unconvinced. “It’s only one of many ideas for the origin of land-dwelling (陆地栖息的) tetrapods, any or all of which may have been a part of the answer,” she said.