The narwhal is the unicorn of the sea, a pale-colored porpoise found in Arctic coastal waters and rivers. These legendary animals have two teeth. In males, the more prominent tooth grows into a swordlike, spiral tusk up to 8.8 feet (2.7 meters) long. The ivory tusk tooth grows right through the narwhal's upper lip. Scientists are not certain of the tusk's purpose, but some believe it is prominent in mating rituals, perhaps used to impress females or to battle rival suitors. Females sometimes grow a small tusk of their own, but it does not become as prominent as the male's. A newborn narwhal calf is about 5 feet (1.5 meters) long and can weigh 175 to 220 pounds (79 to 100 kilograms). Narwhals are normally found in pods of two to ten. They are often sighted swimming in groups of 15 to 20.
Inuit people hunt the narwhal for their long tusks and their skin, an important source of vitamin C in the traditional Arctic diet.
Narwhals can live up to at least 50 years. Females start bearing calves when six to eight years old. Adult narwhals mate in April or May when they are in the offshore pack ice. Gestation lasts for 14 months and calves are born between June and August the following year. As with most marine mammals, only a single young is born. Newborn calves average 1.6 metres (5.2 feet) in length and are dark grey. The newborn calves begin their lives with a thin layer of blubber which thickens as they nurse their mother's milk which is rich in fat. Calves are dependent on milk for around 20 months. This long lactation period gives calves time to learn the skills they need for survival. Mothers and calves stay close and when travelling, the calf stays by its mother's back for assistance in swimming.
Researchers discovered the horn is, in fact, used as a sensory organ.
Stonehenge was built over many hundreds of years. Work began in the late Neolithic Age, around 3000BC. Over the next thousand years, people made many changes to the monument. The last changes were made in the early Bronze Age, around 1500BC.
Some people think that Stonehenge was used to study the movements of the Sun and Moon. Other people think it was a place of healing.
The ancient Britons believed that the Sun and Moon had a special power over their lives. It is very likely that they held special ceremonies at Stonehenge on Midsummer’s Day (the longest day of the year) and on Midwinter’s Day (the shortest day of the year).
Many experts believe that Stonehenge was used for funerals. They suggest that people carried the dead along the River Avon, and then walked up to Stonehenge in a grand procession. The most important funeral ceremony of the year was probably held on Midwinter’s Night at Stonehenge.