Whenever I visit a zoo, I head to the river otter exhibit. I love watching otters swim and play. Unlike most animals, otters always seem to be having fun, although even playful behavior probably helps determine social status.

I first became acquainted with otters when I was about 12 years old. I read the book "Ring of Bright Water" by Gavin Maxwell. I don't recall details of the story; I only know that I've loved otters ever since I read the book.

River otters are large, muscular members of the weasel family. Their thick dark fur consists of two layers -- short thick underfur and longer outer fur. The fur, combined with a layer of fat just under the skin, provides excellent insulation even when swimming in frigid rivers and streams. Thanks to four webbed feet, otters are excellent swimmers.

Otters' favorite foods include crayfish and a variety of minnows, suckers and other small fish. They also eat frogs, turtles, snakes and mussels. Because they are excellent swimmers, otters easily pursue aquatic prey. While submerged, valves close the openings to the ears and nose enabling them to stay underwater up to four minutes.

Best known for what seems to be playful behavior, otters often wrestle with each other and slide down muddy or snow-covered embankments into the water. I've seen such slides in northeastern Pennsylvania, but I've never seen otters use them. My only otter observations have been while canoeing on streams in north central Pennsylvania.

Mating occurs during the first half of the year, but embryos do not implant on the uterine wall until the following winter. This is called "delayed implantation." So right about now, embryos are beginning to develop in Pennsylvania otters. In about two months, females will give birth to two to five kits.

Otters have been protected statewide since 1952, and their numbers have rebounded thanks to a reintroduction program that began almost 30 years ago. Otters trapped in New York, New Hampshire and the northeastern counties of Pennsylvania have been released in watersheds around the state. So if you're ever lucky enough to see an otter in state waters, thank the Game Commission.

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