Welcome to brainstuff, a production of iHeartRadio, Hey brain Stuff Lauren Vogelbaum here. Reproduction is a weird and multitudinous process. Some fish, for example, release their eggs into the water to be fertilized without any direct contact between either parent.
Some living creatures don't need two parents at all, like yeast's the kind we use to make bread that reproduce by a new organism butting right off of a single parent, or mushrooms that release spores which are like seeds, except they don't need to be pollinated to develop into a new mushroom. Even some lizards have been known to lay eggs that develop into a hatchling without having been fertilized.
But in most of the higher animal kingdom, a male animal delivers its sex cells or sperm to a female animal, which keeps its sex cells or eggs inside its body, where the young are nourished and developed until the female animal gives birth. However, not so for seahorses. Male seahorses carrie and birth they're young seahorses. Sea dragons and pipefishes are a family of small marine fishes that tend to
have bony armour and long snouts with fused jaws. They also have the unusual habit of leaving the gestation of their young to the males. They do this in a uterus like pouch, a complete with a placenta found in their tails. A male seahorses have this pouch on the front of their tails. The female seahorse impregnates the male by inserting eggs into that pouch, into which the male releases sperm to fertilize the eggs, and then incubates the
babies for twenty four days. Researchers have found that they even provide the developing young with oxygen and nutrients during this time, like female mammals and some reptiles do. The mechanism behind this process of labor and birth was mysterious for a long time, but an Australian research team has cested out in a study published in September of twenty twenty two in the journal Placenta. The researchers reported that male seahorses labor and give birth in a way that's
very different from other mothers. Female labor in birth is driven primarily by hormones like oxytocin, which can tract the smooth muscles of the uterus to push the babies out. A smooth muscle tissue works involuntarily, whereas skeletal muscles can flex and relax when the brain tells them to, which is why you can probably smile at will, but people
can't go into labor whenever they want. The research team found the muscle tissue of the seahorse brood pouch did not respond to the fish version of oxytocin, but that the pouch itself contained very little smooth muscle tissue. Instead, they found that the male seahorse has three small bones at the opening of the brood pouch, where the anal fin attaches to these skeletal muscles. Female seahorses have very small or not existent anal fins. They are more prominent
in males. It turns out that those anal fins and the skeletal muscles that power them are a key to the mystery of seahorse birth, as they play a role in both mating and labor for the seahorse. During courtship, the male seahorse does a little sit up style dance, a crunching and expanding his abdomen to let water into his brood pouch. He does the same thing when he goes into labor, pressing and relaxing his abdomen until his
thousands of babies few fourth. So instead of smooth muscle running the seahorse birthing show, it's the skeletal muscles of the amal fin the contract to open the brood pouch of the male seahorse. More study is required to test whether seahorses consciously make the contractions happen, or if the skeletal muscles somehow override their normal rules and contract on their own. A seahorse father can give birth to as
many as two thousand babies at a time. The scientists think the reason that males give birth instead of the females is because seahorse babies are often eaten by predators, and so having the male give birth allows the female time to create more eggs to be fertilized without having to wait to give birth herself, sharing that labor insures survival the species. Today's episode is based on the article Yes, malsea horses do give birth Here's how on HowStuffWorks dot Com,
written by Jesslin Shields. Brainstuff is production by Heart Radio in partnership with HowStuffWorks dot Com and is produced by Tyler Klang. Four more podcasts from my heart Radio. Visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.