Misc: Which note does a symphony orchestra tune to?

Questions

All porcupines float in ----------?

Alligators and ---------- have something in common, at least auditorily. They can hear notes only up to 4,000 vibrations a second.?

Almost half the pigs in the world are kept by farmers in ----------?

Although beavers live near rivers, streams, and lakes - they do not eat fish. Beavers eat only plants. They eat poplar trees, carrots, cattail, mushrooms, potatoes, berries, water plants, swamp wood, and fruit. Soft ---------- is the main food for a beaver.?

Although manatees are excellent ----------, the deepest that one has been observed diving is 33 feet. Typically, the large, gentle creatures feed no deeper than about ten feet below the surface of the water.?