Most mammalian, bird and fish reproduction require the female of the species to carry and birth offspring. This is also known as heterogamous where the females have bigger gametes than males, i.e. egg size versus sperm size. What if the roles were reversed? Any men reading this, I’m sorry in advanced but in the Syngnthidae family there are a couple of species where this phenomenon occurs.
Syngnthidae family is a family of fishes that are probably familiar to you. Seahorses, pipefish and leafy seadragons are the well known members. Seahorses are the only species that experience a “true male pregnancy” as the males have physical brood pouches whereas with the other species, the eggs are attached to the tail or trunk by the female and hatch from there.
Seahorses are quite an evolutionary question mark for most scientists. They range from about one inch to one foot in size, have prehensile tails that are able to grab and grip vegetation to keep them from floating away with water currents and they also have bony plates all over their body. As I said earlier, they are considered a fish even though they don’t really look like what we consider a fish to look like. They don’t have many natural predators cause a lot of sea creatures do not like the taste of them, especially the bony plates but they do have a couple of threats which I will get into in a different post. This one is about mating after all. 😉
When a male and female seahorse find the other attractive, they’ll start a mating dance which usually occurs in the predawn hours of the day. Then when things get really serious, a true courtship dance occurs that ends with the female dumping her eggs in the male’s pouch. This can be as quick as minutes or take as long as long as 8 hours. Dancing is a full time job people!
Up to 2,000 eggs can be deposited in the pouch. Two thousand!!!! (I can’t even…) The male seahorse then cares for them by doing things such as regulating water salinity and providing nutrients like glucose and amino acids to make strong seahorse babies. This can take anywhere between 10 to 25 days and then the real fun begins! Like human females, and really most animal species, when it’s time for baby to come, contractions are necessary to push the little one(s) out. Male seahorses actually have contractions as well! Then all 2,000 baby seahorses or “fry” are expelled all at once. After that his fatherly duties are over. Once the fry are out in the world, it’s their responsibility to hurry up and latch on to something with their tails and survive because the parents don’t help them at all. Because of this, only about 10 of the fry will survive to adulthood. It’s hard out there for baby fry. However, females are able to implant males with more eggs again as soon as the first litter is released. This process can go on all day long because they want as many fry to survive as possible and in order for that that happen, men have a job to do!
Check out the video below to see this in action. I showed it to my husband and his eyeballs went huge and he is now very grateful to be a human male instead of a seahorse male.