Just when you thought you knew all there was to know about the “birds and the bees,” the reproductive life of the seahorse comes along. In a very unique anomaly of nature, it is the male of the seahorse species that gets pregnant and gives birth to the next generation. Just how this happens is a fascinating story.
Reproduction in the seahorse begins with a courtship period. Although many seahorses appear to develop monogamous relationships, there are also a number of species that mate only for a single mating season which, for seahorses, occurs between May and August. Seahorse courtship is a beautiful affair, with synchronizes dancing rituals taking place for several days before the reproductive interaction takes place.
The physical similarities between the male and female are striking. The only discernible difference scientists have been able to find is in the abdominal area where the female is rough and angular. The male is smooth and the reproductive pouch is visible.
When the time comes for the mating process the seahorses entwine their tails and the female inserts her oviduct into the brooding pouch located on one side of the male’s body where they are fertilized. She will usually deposit several hundred eggs, generally making several deposits before the reproductive act is over. Between deposits the male will twist and turn to get the tiny eggs lined up in the pouch.
After the deposit has been completed, the male moves away and uses his tail to attach himself to a plant. The female backs off as well to allow her oviduct to recede back to normal.
During the pregnancy, the female seahorse will check on her mate daily, showing all the concern of a caring partner. Gestation can last anywhere from two weeks to more than six weeks, depending on the species of seahorse, with most species leaning towards the lower end of the scale. Much like the hormonally ravaged partner of any pregnant couple, the male will often show aggression to any creature that approaches, all in an effort to protect the young growing in their pouch. The male body will puff up as the time of birth comes near. This increased size is thought to be a defense mechanism to keep predators at a safer distance.
At the time of birth, the brooding pouch extends and the male undergoes a period of muscular contractions where he bends forward and backward. After a short period of time, usually about ten minutes or so, the baby seahorses will be released into the water, looking like miniature versions of their parents, at which point they are basically on their own. Infant mortality in the seahorse world is extremely high with very few living long enough to mature and mate on their own, contributing to their growing risk for extinction. Those that do survive can expect a life span between four and six years.