Tish Mockler, age 11, of Omaha, Neb., for her question:

WHY ARE WHALES CALLED FILTER FEEDERS?

Certain of the great whales are called filter feeders because they filter their food from gallons of sea water. Others are called toothed whales because they have teeth to bite off huge helpings of meaty food. The most famous filter feeder is the blue baleen whale, a gentle giant who happens to be the biggest animal that ever lived on earth.

A baleen whale has no ordinary teeth. Instead, there are curtains of pliable strips hanging down from the roof of his enormous mouth. This gristly material is called baleen or whalebone. When he opens his big mouth, it fills up with watery plankton. Then he closes up and uses his whopping tongue to squeeze the water through his balleen. This filters out the mini plants and animals in the plankton  which he swallows.