Eels are interesting because they live part of their life in freshwater and part in sea water. They are born in the sea and migrate up into freshwater to grow. When they reach maturity, they then make the long journey back to the sea to spawn. In dry weather puddles can form, which leaves the eels no choice but to move across land. How does an animal that lives in water manage to do this? Eels can survive out of water for many hours, and part of the reason is because they have a very thick skin, which seems to cut down their rate of water loss and stop them from drying out. Fish are also able to use oxygen very sparingly and don't need an enormous amount of oxygen to keep them going. Eels have been found on land and they can navigate, although we don't know how. Their movement is quite like a snake. They like to go at night because it's cooler and they don't lose as much water.

It depends on relative speed of predator and prey. If you imagine a t-rex, it is very big and very heavy. The legs have to take weight of the body at every stride and so they have to be strong enough to support them. Their legs were enormous and we can estimate how strong they were. It has shown that it is unlikely that they would have been able to run very fast: maybe about 20 miles per hour. That's a t-rex. The smaller light things like ostrich dinos, are light and long-limbed. They have the physical construction that would have allowed them to run faster. So it's all to do with scale. Smaller, lightly-built animals would have been able to run faster as long as their lungs were built in the appropriate way.

They name dinosaurs after something distinctive. I named a dinosaur not so long ago because it had a big nose. We tend to use Latin or Greek words because of tradition. We know how old they are because we use isotopes to date particular bands of rock, and thus infer from that how old the fossils are.

We will eventually become extinct but we don't know when that will be. Most species live between 3 and 5 million years, so we are around for some time yet.

You can tell ethnic group from DNA, but not the individual country. The only way I can think to do that is to look at his teeth, which sometimes trap geological signals. If these were laid down at the beginning of his life, you would have a fingerprint of where he came from.