CHATTANOOGA, Tenn. (Feb. 21, 2002) - Mythical, marvelous and amazing - no matter what word is used to describe them, seahorses capture the imagination as some of the sea's most unusual inhabitants. But one of the most fascinating features of seahorse behavior is the way they woo and then brood.

It all begins with a slow, dance-like promenade through the sea grass. The male, head bowed, performs an elaborate dance around the female, often wrapping his tail around her or mimicking her movements. The male often changes color, his body becoming lighter while his spine area darkens. During this mysterious mating dance, the male opens his empty pouch to the female. If the female is satisfied, she raises her head and intertwines her tail with his.

"The ritual can last up to nine hours and resembles a sort of ballet," said Thom Demas, Tennessee Aquarium senior aquarist. "The seahorse pair travel up the water column as she transfers eggs to the male seahorse's pouch on his abdomen, where he fertilizes the eggs and goes through the pregnancy."

In all species in the family Syngnathide - seahorses, seadragons and pipefish - it is the male who carries and nurtures the eggs. In the case of seahorses, the male actually becomes pregnant. Each fertilized egg embeds into the lining of his pouch, where tissue grows around the eggs and supplies them with oxygen throughout the pregnancy. This tissue does not supply nutrients to the eggs; the main source of nutrition is in the yolk of the egg itself.

The male seahorse carries the eggs for a period of 10 to 30 days, depending on the species and water temperature. The babies, which can number between 10 and 500 depending on the species, emerge as tiny replicas of the adults, ready to begin life on their own.

Most seahorse pairs are monogamous - once a male and female form a pair bond, they mate exclusively during the breeding season.

Seadragons, however, have a different style of breeding. With the approach of warmer weather, male and female seadragons form pairs. Once paired, both seadragons keep close together, never floating too far away from their mate. The female seadragon develops up to 300 orange eggs within her lower abdominal cavity. During this period, the male goes through some of his own interesting transformations. As the eggs are developing in the female, the tail of the male enlarges and becomes wrinkled and a network of fine blood vessels develops. Once the tail is fully enlarged, approximately 120 small pits, or eggcups, appear in preparation to receive the eggs. The female then deposits the eggs into the cups, and the male fertilizes them.

It takes weeks for these transformations to occur, and during that time the male seadragon can be seen displaying to the female. He swims alongside her in a distinct head-up-head-down motion. Sometimes the female returns a similar motion to the male. Occasionally, the male approaches the female from the front, turning his body upside down, possibly showing off his readiness to reproduce. He also becomes extremely aggressive during this period, chasing away any potential predators from the female. When the egg transfer occurs, the female floats upward in an exhaustive state.

Pipefish also have interesting mating characteristics. Like seahorses and seadragons, the male is the primary carrier of eggs, but in some species, the female carries them. In contrast to seahorses and seadragons, pipefish are not "monogamous." The female leaves her eggs with several different males, and males may carry the eggs of several females at one time. In most cases, the carrier pipefish attaches the eggs to the underside of the belly, where they are fertilized and incubated. Certain species, such as the banded pipefish, dance with one another during this courtship. They snake between one another, often bending their bodies in the shape of a half circle or a cross. From time to time, both move their heads simultaneously in a special rhythmic bob. Once the dance is finished either the male or female swims off, with eggs attached to its abdomen.

After the young hatch, their parents play no role in their upbringing. Very few young seahorses survive to adulthood, falling to predators, swept away by ocean currents or harvested by humans for a variety of uses.