It was not the monster hitting the water but a satellite, and that supposedly is the cause for the monster coming to shore. According to the production notes, the monster is actually thousands of years old. Check it out here:
http://www.comingsoon.net/cloverfieldnotes.doc
http://www.scifijapan.com/articles/2...duction-notes/
Supposedly, the sequel will not be a real sequel, but another view of what transpired that day, perhaps from the government's/scientists' point of view this time to clear up the monster's mysterious origin.
The monster is not supposed to have malicious intents like the aliens from War of the Worlds. It's simply confused and we're like ants bothering it because it accidentally stepped on our "nest". The little critters falling from it are also not there to do its bidding but parasites, like barnacle found on a whale. The parasites fell off when the monster was scratching its back against the skyscrapers.