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February 2003



seahorse Male pregnancy: seahorse style!

Jim Morel

A pregnant male seahorseThink about this for a moment. In the animal kingdom it is mostly the male that competes against other males for a female partner. For example, many male birds have bright colours and fancy plumage to attract a female partner. Males in some other groups have large tusks or horns to show strength and their ability to protect the female and her young.

Now in the seahorse world, things are a little different…..well so we thought. Since it is the male that becomes pregnant and gives birth to the live baby seahorses, it would seem logical that the female seahorses compete amongst themselves for male partners to care for their eggs. Well, that is what we thought. However, research has shown that it is STILL the males that compete for females. When male seahorses want to impress a female, they have tail pulling competitions, dragging each other around on the bottom of the seabed. They also snap at each other with their snouts and wrestle with each other using their long curved necks. They also display their pouches to the prospective female by opening and closing them, filling their pouches with water and expelling it with force, to show the fitness of the pouch for the birth process.

So, in a nutshell. Male seahorses compete with each other to become pregnant for three weeks (during which time they cannot move around to search for the best food), go through 72 hours of labour and exhausting final contractions to release up to 200 baby seahorses. During this process the natural colour of the male seahorse drains from his body and he becomes white and pasty looking. The experience (yes, we have it on film) looks painful and I cannot imagine that he would want to experience a baby seahorse birth again. But, after a very short time, sometimes only hours, the male starts showing off his pouch, begging to be pregnant again.

Not quite Ripliey's but something to think about.

Seahorses are thought to have evolved at least 40 million years ago and have survived from ancient times with only very small changes in body structure or organ function. They are unusual fish that have captured the imagination of artists, writers and poets, being found in the mythology, legends, folklore and superstitions of almost every country in the world. In fact some people still believe that these endearing creatures exist only in fables and children's stories. The fact is however, that these creatures are just as real as the threats that they face in our world today.

Seahorses are unique in appearance, resembling an amalgamation of body parts taken from numerous animals: a horse-like head, a monkey-like prehensile tail, chameleon-like eyes and insect-like body armour, but they are, however a peculiar species of fish equipped with a backbone, (unusual grape-like) gills, swim bladder and fins. The scales of the seahorse have over time fused to form the locust-like exoskeleton.The seahorses mate monogamously for the entire breeding season. Every day the pair will come together in a ritualistic flirtatious dance to reinforce their connection. While the male is pregnant he will move very little, which for a seahorse means not more than a few centimetres.

The male will eat food that happens to be in the area while the female will roam about in search of food. Regardless of this separation however, the female will always come back to the male to perform their daily ritual of entwining their tails and spiralling to the surface in a dance of celebration.
This ritual helps keep the pair synchronized reproductively. If a mate is removed or dies, it will take weeks to find a new mate, that is, if it is able to at all!

This is because seahorses live in isolated groups and move very little. It is thus extremely difficult to find another seahorse in the same part of the reproductive cycle. Due to the fact that it is the male that becomes pregnant it was previously believed that it would be the females that competed for the male partners.

This however is simply not the case. Like in most species, it is the male that competes with other males to attract and defend his female seahorse. So, it would appear that the male actually wants to be pregnant. The seahorse male is sounding more and more like every woman's perfect mate!
I suppose at the end of the day, the seahorse is no different to our own behaviour in many ways, especially around the time of Valentine's day!!!

For more information: 

Jim Morel
Knysna Seahorse Project
Postnet suite 24
P/Bag X31
South Africa
Cell: +27 (0) 834 00 3266

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