By Kayden Mitchell Of all the mysteries in the world, none has been as popular as that of the Loch Ness Monster. Perhaps the biggest mystery is whether it is convincing evidence or a simple desire to believe that keeps the myth alive. Loch Ness is a lake in Scotland. The loch, or lake, is known for sightings of a mysterious monster. Most who see this monster, known as Nessie, describe something with a long neck and several humps above the water. Sometimes the "monster" is moving in these sightings, and sometimes it is still. Many have suggested that Nessie might be a plesiosaur (plea-see-a-soar), an aquatic dinosaur that was trapped in the loch after the last ice age. The plesiosaur theory presents several problems. First, the plesiosaur is an air breather. Such a creature would need to surface often and, therefore, be seen more frequently. Second, it's unlikely that the same creature has lived in the loch since the last ice age. Today's creature would have to be the offspring of an original plesiosaur trapped long ago. This would suggest multiple creatures in the loch (needed to produce offspring). Again, sightings would be more frequent if this were the case. So from a purely logical stand point, the existence of such a large and ancient creature is unlikely. But assume for a minute that it is possible. What would a plesiosaur need to live in an enclosed lake? Tropical waters: Scientists believe plesiosaurs were warm-blooded. Like crocodiles and alligators, plesiosaurs would need to live in warm waters. The loch is very cold with temperatures averaging about 40 degrees Fahrenheit (4.4 Celsius). Food: Like other warm-blooded creatures, plesiosaurs would need a large quantity of food. If there is a group of Nessies, then even more food would be needed. Because the loch is full of silt (underwater dust) not much light gets into the deepest areas. So the food chain, which would depend on plankton, is very weak at its base. As a result, there is probably not enough food to support such a large creature. However