Male swans are called cobs, females are known as pens, and the downy young are cygnets.

If you see a swan with its foot out of the water, it either cools or warms itself, depending on the season. A close look at their webbed that it has numerous veins and arteries.

What is that black knob at the top of their beak? The knob is called a basal knob. When the scientists figure it out, they will let us know. They may serve as an indicator of health or sexual maturity. They tend to be more prominent in males. It grows larger in the male during mating season.

Mute Swans form long-lasting pair bonds.

One Maryland study found that they are big eaters, eating up to 8 pounds of vegetation a day and often outstripping the vegetation's recovery capabilities.

They can be extremely aggressive and have threatened native waterfowl.

They can be highly aggressive and have threatened native waterfowl. Mute Swans are not silent. They are less vocal than other swans. They do make hissing noises.

They have a wingspan of seven to eight feet.