In nature, it’s usually the females who carry and give birth to the young. But nature is full of surprises! There is a fascinating group of animals where the roles are completely reversed, and the males take on the task of pregnancy. These dads carry the eggs with them until they hatch. Dive into the wonderful world of male pregnancy with these 4 extraordinary examples.
1. Seahorses are the most famous pregnant dads
The most iconic example of male pregnancy is undoubtedly the seahorse (genus Hippocampus). During mating, the female deposits her eggs via an ovipositor into a special brood pouch on the male’s abdomen. This pouch resembles a kangaroo’s pouch.
Once inside the pouch, the male fertilizes the eggs. The inner lining of the pouch is rich in blood vessels and functions like a womb. It provides the embryos with oxygen and nutrients and regulates salinity. The male carries the eggs for weeks, depending on the species and water temperature.
When the young are fully developed, the male expels them with powerful contractions of the pouch. This resembles childbirth and can last for hours, sometimes resulting in hundreds of tiny seahorses being ‘born’.
2. Pipefish carry eggs on their belly or tail
Pipefish (family Syngnathidae, which also includes seahorses) are close relatives of seahorses and also exhibit male pregnancy, though often in a slightly different way. Many male pipefish do not have a fully enclosed brood pouch like seahorses.
In some species, the female attaches the eggs to a special strip of skin on the male’s belly or tail. In other species, skin flaps develop that partially or fully cover the eggs, sometimes resembling an open pouch. The male fertilizes the eggs and carries them until they hatch, also protecting them and providing oxygen.
3. Seadragons have colorful ‘brood patches’
The beautiful seadragons, such as the leafy seadragon (Phycodurus eques) and the weedy seadragon (Phyllopteryx taeniolatus), are also related to seahorses. Here too, the male carries the eggs. The female lays her bright pink eggs on a special brood patch under the male’s tail.
This brood patch consists of small ‘cups’ into which the eggs fit perfectly. The male fertilizes them and carries them for about a month until the tiny seadragons hatch. His camouflage among the seaweed helps protect the eggs.
4. Some mouthbrooding fish carry eggs in their mouths
Although technically not ‘pregnancy’, mouthbrooding is another form where males take care of the eggs. In some species of cichlids and cardinalfish, the male takes the fertilized eggs into his mouth and keeps them there until they hatch. He does not eat during this period and protects the eggs from predators.
7. Why do males take over care?
The evolutionary reason behind male pregnancy and intensive brood care in these fish is complex. Theories suggest it might increase reproductive rates (the female can produce new eggs sooner), enhance the survival chances of the young, or assure the male of his paternity. It shows that nature has flexible solutions for reproduction.
Conclusion: The Wonderful World of Pregnant Fathers
The animal kingdom continues to amaze us with its diversity of reproductive strategies. Seahorses, pipefish, seadragons, and some mouthbrooders spectacularly demonstrate that the role of ‘pregnant parent’ or primary caregiver is not exclusively reserved for females. These dedicated fathers invest enormous energy in carrying and protecting their offspring, a fascinating example of how evolution can find the most unexpected solutions.
