Study Finds How Seahorses Give Birth: Is It Similar To Labor In Female Mammals?

A new study has discovered a unique way in which seahorse dads give birth to their young, which sets them apart from other female pregnant animals.

Putting patriarchy to shame, seahorse males take it upon themselves to carry their embryos in their pouches till they are ready to be expelled into the outside sea world. Previously, it was believed the mechanism of parturition (birth) in seahorse mammals was akin to labor in human females.

However, the study that has been published in the journal Placenta has something entirely different to say. Seahorse males have been found to have special bones and muscles near their pouch opening that facilitates contraction and widening of the pouch for birth. These bones are absent in their female counterparts. The pouch in male seahorses can be equated to a uterus in other pregnant mammals.

The study started with the assumption that seahorse labor is similar to that in other female mammals.

To explain the parturition process in female mammals in a simplified way, the smooth muscles of the uterine wall of the female contract in response to the release of a hormone called oxytocin and as these contractions become intense, the baby is pushed out.

In seahorses, a similar process was believed to occur. In fact, a 1970 study observed non-pregnant seahorse males exhibited labor-like behavior when they were exposed to isotocin -- a member of the oxytocin family.

Surprisingly, the current study was unable to replicate this association in the seahorses. It was seen that isotocin had no visible effect on production contractions in the seahorse pouch.

This led the scientists to examine the anatomy of the pouch present in seahorses. The comparison between male and female seahorse pouches gave away the answer. Male seahorses had three bones associated with large skeletal muscles near the pouch opening, a feature missing in the females.

These types of bones and muscles generally function to control the anal fin in other fish. But the seahorse has a rudimentary anal fin, which has no real purpose in swimming. This turned on the light bulbs.

The study proposes that through a process of elaborate maneuvers, the male seahorse gives birth to their young using the extra muscles and bones that it has been endowed with.

The contractions are said to be conscious as opposed to subconscious contractions in other female mammals because the contractions in female mammals are of the smooth muscles, which are involuntary in nature and the contractions in the male seahorses are of the voluntary skeletal muscles. Simply put, animals have no control over involuntary muscles while skeletal muscles require conscious efforts to be contracted.

The research team speculates that the oxytocin-family hormones play a role in stimulating a series of seahorse behaviors that lead to birth, but the role of the skeletal bones and muscles is pivotal to the labor process in the seahorse daddies.