Well, it’s not exactly singing, but some fish can make musical sounds. The siren fish of the Mediterranean can make a tuneful noise by gratin its teeth together, and the drumfish is so called because it can make a noise like a drum, so loud that fisherman sixty feet above it on the surface have heard it.

Two male Siamese fighting fishes placed in the same aquarium instantly take up aggressive positions ready for a scrap. Their colours deepen, their long flowing fins becomes erect and they suddenly slash at one another at lightning speed. The fight is very dramatic and can last for up to an hour before one of the pair becomes too exhausted or …

Experts studying different human populations are very interested in the distribution of blood groups. For example, it has been noted that Amerindians (American Indians) are practically always blood group O. There are very few pure Amerindians with blood group A, and group B is conspicuous by its absence. Asiatics have far more member of group B than Europeans Among Europeans, …

No. There are 230 joints in the body and all play their part in allowing the skeleton to maintain its shape and, in some case, to move. Some of the body’s joints, however, do not move at all the cranial bones of the skull, for example. Other joints, such as the elbow joint, allow movement in one direction only.

The first submarine to go into action was an American vessel called the Turtle. It tried to attack a British warship in 1776, during the American War of Independence. The Turtle was an egg-shaped craft powered by one man, who sat inside and turned two handles connected to screw propellers outside. Manned by Sergeant Ezra Lee, the Turtle’s mission was …

The answer, in the modern use of the world flag, is ‘no’. The world is of Germanic origin and was used in the fifteenth and sixteenth centuries to mean a piece of cloth, or other material, displaying the insignia of a community or armed force, an office, or an individual. They were used originally mainly in warfare, and were signs …

Surgeons can cut tissues without using knives. They use a laser beam which delivers intense heat to the tissue. The beam cuts effortlessly and with total cleanliness. It also seals blood vessels so that the cut does not bleed. Eye surgery can also be carried out by laser-without cutting open the eye! The retina at the back of the eye …

It is possible that robots may begin to perform some surgical operations on people. The robot would be directed with great precision by a computer working from pictures of the inside of the patient’s body taken with scanners. The computer would be controlled by human surgeons, who would check the progress of the operation on video screens. Robot surgery could …

These animals are all represented by star patterns known as constellations. A total of 88 constellations fills the entire sky, and some of them have very odd names. The most famous constellations date back to the ancient Greeks and Romans, but imaginative astronomers have introduced additional ones since then. Among the constellations is a dragon, called Draco, coiled around the …

We think of robots as perfect machines that never do anything wrong, let alone get hurt. However, there are some robots whose whole purpose is to get hurt and to say ‘ouch’. These robots are dummy patients for dentists. They have a model human head, and student dentists practise doing fillings and other kinds of dental work on the robot’s …