what word links these: ambulance, field, pocket?

Questions

A ---------- has no color vision, it sees only in black and white. Every part of its field of vision, however, is in perfect focus, not just straight ahead, as with humans.?

A ---------- never actually sees the food as it eats, since its eyes are on top of its head and its mouth and nostrils are on the bottom.?

A tiger's paw prints are called ----------. A tiger's forefeet have five toes and the hind feet have four toes. All toes have claws. The claws are 80 to 100 mm in length.?

A ---------- fish can swim 100 miles in a single day.?

A type of lizard, the ----------, escapes pursuers by crawling into a crack in a rock and inflating its body with air so that it is wedged tightly into the crack and can't be pulled out.?