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Are zebra mussels saltwater or freshwater animals?

Montana, age unknown

Zebra mussels are a freshwater species native to rivers and lakes in Eastern Europe and western Asia. The first American sighting of zebra mussels was in Lake St. Clair, which is between lakes Huron and Erie, in 1988. Zebra mussels have since colonized much of the Great Lakes and have been found in the Mississippi and Missouri rivers, as well as in other lakes and rivers around the country. Scientists think zebra mussels came to the U.S. in the ballast water of ocean-going ships. Laws now require ships to dump ballast water at sea. Zebra mussels and many other invasive freshwater species cannot survive in saltwater.

Do all birds have a gizzard?

Shelby, 11.

Most birds have a gizzard, a chamber in the stomach where powerful muscles grind the food they have eaten. The grinding is an alternative to chewing, which birds can't do because they have no teeth. Many birds swallow gravel, sand or other coarse material to help them to grind their food in their gizzard.

Do you think chronic wasting disease will get to the Ozarks?

Michael Taylor, 13

We haven't found CWD yet, and we've tested more than 12,000 deer in Missouri over the past two years. Chronic wasting disease aff ects deer and elk. Victims seem to “waste away” as their brain deteriorates.

The Centers for Disease Control doesn't consider chronic wasting disease to be a human health issue. If the disease came to our state, however, it would aff ect the way we manage our deer herd. That's why the Conservation Department continues to test deer for CWD and is cooperating with the departments of Health and Agriculture to keep the disease out of Missouri.