Romance of the Sea

Love is a many-splendored thing, and nowhere is it more splendid — or strange — than in the ocean. For marine animals, reproduction involves not just romance, but also fencing, sex change and cannibalism. 

Read on to learn some of the bizarre marine life mating rituals.

Sea Horses

Sea horses are beautiful, graceful creatures that often court for several days. During that time, they undergo a beautiful dance in which they swim side-by-side and mirror each other’s movements. Sea horses are unique in that males carry the babies. How’s that for swapping gender roles? Males have a pouch on the side of their body into which the female will inject up to 1,500 eggs. The male will carry the eggs for a few weeks and then the baby seahorses will emerge, fully developed.

Nassau Groupers

Nassau groupers aggregate to specific spawning sites on the full moon during December and January. This peculiar timing is of particular interest to scientists, who have suggested that, like other marine mammals, the gravitational pull of the moon at this specific time of year inspires migration to breeding grounds. Spawning aggregates can be as large as 100,000 individuals.

Like other groupers, Nassau groupers are considered hermaphrodites, meaning juveniles contain immature gonads for both genders and then directly mature as either male or female.

Flatworms

As is it turns out, flatworms have one of the most intense and violent mating rituals on earth. Those colorful little guys you sometimes mistake for nudibranchs battle their mate as part of the reproductive process.

Flatworms are hermaphrodites (naturally both male and female). When it’s time to reproduce, they fight each other with their male organs – each attempting to inseminate the other.  In these contests, the victor is the worm that succeeds in injecting its partner first. Not only does the winner end up “fathering” more offspring, it also ends the encounter with fewer wounds to heal. The loser limps away injured and with more fertilized eggs to carry.

Puffer Fish

Puffer Fish make the ornate circles to attract mates. Males laboriously flap their fins as they swim along the seafloor, resulting in disrupted sediment and amazing circular patterns. Although the fish are only about 5 inches long, the formations they make measure about 7 feet in diameter.

Once the circles are finished, females will come to inspect them. If they approve, they will mate with the male and lay their eggs in the circle.

These are just a few of the many stories the ocean has to tell about how marine species reproduce, but they’re among the most interesting. Knowing which strategies different creatures employ can increase our chances of stumbling upon fascinating behaviors while diving, so keep learning, and keep looking. The more you know, the greater your odds of witnessing new life in the making.