A.... This is known as hydrogen bonding because the highly electronegative Oxygen in on molecule of water is attracted to the Hydrogen of another.
The reasons are:
- the blood is very low on nutrition
- the leech is not feeding itself regularly
The leech slows it metabolism a lot, so it can survive on very low nutrition. The blood is very low on nutrition, and it is the leech's food source, so the evolution made it preserve energy.
The leach doesn't have the opportunity to feed itself on regular basis, so it takes maximum advantage of any opportunity and consumes as much blood as possible so that it can survive long term when it will not have food at disposal.
Decrease in the tree population can damage the environment.
Natural selection it has to be 20 characters so disreguard the rest
