How Long is a Lamprey and What Fish Does It Live On?

Adult sea lamprey range from 14 to 24 inches in length. Sea lamprey uses its suction disk mouth which is filled with small sharp, rasping teeth and a file-like tongue to attach to fish, puncture the skin, and drain the fish's body fluids. An anticoagulant in their saliva ensures that the blood of the host fish does not clot while the sea lamprey feed.

Often the host fish die from loss of blood, or infections resulting from stress. Fish that survive sea lamprey attacks will have decreased reproduction. Sea lamprey in prefer landlocked salmon, lake trout and other trout species, due to their small scales and thin skin.

Why Do Fish Swim in Schools?

Fish swimming together is a great example of "safety in numbers". In a school, the fish in the middle of the group are well protected from predators and the abundance of the fish in one area may confuse actually confuse the predator making them less efficient on hunting.

There is one downside to being in the middle of the pack - lack of oxygen. Scientists have found that fish swimming in the middle of a school have access to 25% less oxygen than the fish swimming on the periphery. This causes the school to change shape frequently as fish move from the inside to the outside of the formation.

Do Fish Sleep?

This question gets asked about a lot of sea animals. Most animals need down time to re-energize or evade predators. While this is often called "sleep", sometime hibernation might be a slightly closer term.

Fish do not have sleep like higher primates. They do not close their eyes or have REMs but scientists feel certain they experience a rest period when all body functions have slowed to a minimal level.

What Can You Tell Me About The Electic Eel?

The eel is really not an eel - it is closer to a carp and yes, it does generate electricity!

These awesome freshwater predators get their name from the huge electrical charge they can generate to stun prey and avoid predators. Their bodies contain electric organs with about 6,000 specialized cells called electrocytes that store power like tiny batteries. When threatened or attacking prey, these cells will discharge simultaneously, sending out a burst of at least 600 volts, five times the power of a standard U.S. wall socket.

If you want to see these fish in their natural habitat you need to travel to South America. There they grow to be over 8 feet (2.5 meters) in length and 44 pounds (20 kilograms) in weight.

Source:http://animals.nationalgeographic.com/animals/fish/electric-eel.html

Do Fish Have Saliva?

A fish does eat with its mouth and has many organs that are similar to a human so your question is logical.

The buccal cavity of the mouth secretes mucus to aid in the swallowing of food, but there are no salivary glands. This mucus is a only a lubricant, it contains no digestive enzymes like mammalian saliva. So no food is chemically altered in the mouth.

Source: http://www.earthlife.net/fish/digestion.html