In March 2013, on a rainy night, my partner Reece remembered that he had forgotten a box in his car and went out to get it. On his way back inside he noticed a small shadow moving on the driveway. As Reece moved towards the shadow, he realised it was a young hedgehog(刺猬), all wet in the grass，eating mud. He quickly removed his jacket and picked it up. The hedgehog was very weak and unable to move about quickly. He didn’t seem to be frightened, nor did he resist being lifted.

Once inside, Reece called out to me, saying that he had something that would make my heart melt-he was right! We named the hedgehog Alf, and this little creature was amazingly intelligent. Not only did he learn to cat his dinner and drink water from his bowls, and use a paper-covered mat for his “business”, but he also learnt to wait for us inside his little indoor house and also jump into his pet carrier whenever we took him out with us. Alf knows us very well and recognises both our voices Unfortunately.in April 2014. I was caught in a car accident and had to spend two months in Auckland City Hospital. And I really missed Alf. Reece told me that Alf had been searching around the house for me, checking in places where I’d normally be, such as my desk, my favourite seat in front of the TV and even my side of the bed.

One evening, Reece set up a video call for me from my hospital bed and I was extremely happy when I saw the little guy appear on my phone. When I told Alf that I would be home soon, he started moving his head and holding out his arms as if trying to reach me through the screen.

The fact that Alf recognised that it was me, gave me the strength to get through my recovery. I cannot describe the feeling when I arrived home and saw his little face again.

Native to forests of Central and South America, glass frogs in the Centrolenidae family get their name from their skin and muscles that help them be perfectly fit to live in their jungle environment. Turn the frogs over, where the effect is the most impressive, and you’ll make out their hearts, livers, and other organs through their hyaline stomachs.

And in a study published in the journal Science, researchers have discovered an amazing mechanism (机制) the animals use to become so clear.

When glass frogs go to sleep, they take in 89 percent of their brightly colored red blood cells into sacs (液囊) in their livers, which reflect incoming light and make the frogs appear nearly unseen. With their red blood cells out of view, the frogs become twice to three times more clear -a trick scientists believe helps the animals avoid being killed and eaten by their natural enemies.

“The trick is really hard to do, because their tissues are full of things that take in and spread light. And transparency (透明) is normal for many creatures in water, but hard on land,” says study co-author Jesse Delia. “Red blood cells also take in a lot of light, and we found that the frogs can actually hide themselves by packing them into the liver.”

Not only are the findings interesting, but the researchers attach great importance to them. That’s because many red blood cells in one place usually form a clot (血块), which can block and lead to a potentially life-threatening condition. But the frogs can seemingly clot and expand their red blood cells at will — without any negative effects. This may mean the animals already have what medical researchers have been seeking for decades: a biological mechanism which prevents too much bleeding while also preventing too much clotting.