Why Do Male Seahorses Give Birth? How Is It Possible?

Ayan Banerjee
Mar 09, 2023 By Ayan Banerjee
Originally Published on Oct 11, 2021
Edited by Katherine Cook
Fact-checked by Pradhanya Rao
Male Seahorse swimming around green weed
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Age: 3-18
Read time: 7.4 Min

A seahorse is a small, tiny marine fish belonging to the animal kingdom.

Seahorse species are widely used in the aquarium trade. Seahorses acquire their name from their evolutionary equine look which includes bent necks, large snouted heads, and a unique trunk.

Seahorses are tiny, slow-moving fish and are poor swimmers because of which they are most often spotted resting in the sea with their prehensile tails wrapped around a fixed item. These smooth and lined seahorses, as well as their relatives, are the most common species of wild seahorses seen in aquariums.

Seahorses in aquariums eat shrimps slowly and methodically.

Because seahorses are not aggressive like other fish, they can be housed in an aquarium with other types of invertebrates or other fish. Due to shallow water in the past, seagrass habitats would have expanded, providing concealment for seahorses' straight posture, according to science.

Seahorses belong to the animal kingdom and are one of the sea's most unusual species in the world, but with time, human activities have lowered their count. It is a frequent misconception that seahorses mate for life.

Male seahorses carry the infants because it allows the species to produce more babies and deliver them into the sea more quickly.

Many animals mate for life, but seahorses do not. They can stay together for a short time before moving on in search of a new mate.

Unlike other animals, seahorses go through four stages of courting, each marked by distinct behavioral changes and fluctuations in the intensity of the wooing act. The female pointing behavior, in which the female raises her head to establish an oblique angle with her, marks the second phase.

In phase three in response to the female, males will initiate the same pointing activity.

Finally, they will rise together repeatedly with the female transferring her eggs directly into the male's brood pouch, resulting in the male sex becoming pregnant. There is a lot more science behind seahorses that evolutionary biologists are currently studying.

If you enjoyed this article, why not also read about why do whales breach or why do oysters make pearls here on Kidadl.

Which other male species give birth?

The majority of animals in the world reproduce with the help of sexual reproduction, with females producing a high number of eggs and males producing a smaller quantity of sperms.

Male pregnancy occurs not only in seahorse species but also in the near cousins or close relatives of seahorses, unlike in humans beings. According to scientists, members of the Syngnathidae family are the only members of the animal kingdom that practice male pregnancy.

These species include pipefish, weedy and leafy seadragons, and the Surinam toad.

Pipefish are close relatives of seahorses and have evolved from seahorses and show polyandry where the female prefers two male partners for reproduction or mating according to research.

In the case of pipefish, however, the male may choose to digest the embryos when no food is available, rather than aid them to survive or if he just does not find his female spouse attractive. A pouch is found on the ventral side of the male's tail.

When a female seahorse mates, she can lay up to 1,500 eggs in the male's pouch. The male will carry the babies until they are fully developed which takes 9-45 days).

During the breeding season, the babies are released into the sea and the male often mates again within days.

Do only male seahorses give birth?

The Syngnathidae family is distinguished by a highly evolved type of male brood care. With roughly 300 different kinds of fish, the family is quite diverse.

Some of the males in this species have a brood pouch on their tails. When female seahorses lay the eggs, the male's trunk or tail will carry them.

Unlike other animals, their definition of pregnancy is different because males get pregnant even in the absence of an external brood pouch. Before implantation, fertilization takes place inside the pouch or in the water, followed by fertilized egg incubation.

Developing embryos or the fertilized eggs require a proper pH. The males provide their developing offspring or young ones with nutrients such as amino acids and glucose. Female seahorses have an ovipositor, a device that helps them shoot the eggs into the male's pouch, where he can incubate them until they hatch.

He expels small seahorse babies after the eggs hatch and it takes a lot of work. They are on their own after the babies are delivered.

Baby seahorses have a high mortality rate. It is not only male seahorses that give birth to babies, but there are also other other male species that give birth to their young ones.

Male Seahorse with pregnant belly

When do male seahorses give birth?

The number of eggs released by male seahorses can vary between 100-1000. It can be lower for smaller species and higher for larger species. The male expels the offspring using muscular contractions.

When they mate, the female deposits all of her available eggs in his pouch and she needs time to produce additional eggs. Males can deliver kids in the morning and become pregnant again on the same day! There are numerous predators of seahorses including sting and manta rays, crabs, penguins, sea birds, and bluefin tuna.

According to scientists, male seahorses normally give birth at night and are ready for the next batch of eggs by morning when their mate returns in search of them, according to scientists. Seahorses, like almost all other fish species, do not care for their young once they are born.

Predators and sea currents can wash infants away from feeding sites or into temperatures that are too hot for their tiny bodies. Research undertaken has found that about 0.5% of newborns survive to adulthood.

This involved a higher survival rate compared to other fishes because of their protected gestation, making the process worth the cost to the male. Most other animals leave their eggs immediately after fertilization.

Does it hurt male seahorses to give birth?

The male seahorse must expend a lot of energy during reproduction or the mating process. This raises the question of why seahorses display a sexual role reversal in the first place in a situation where one parent exerts more energy than the other.

Male seahorses are more aggressive than female seahorses and they may battle for female attention. Researchers or scientists studied the energy stored in each egg to estimate the female's independent contribution.

Oxygen consumption was employed to determine the male's burden.

By the end of the incubation period, the male had used over 33% more oxygen than he had before mating. The scientific study found that a female's energy expenditure during the production of eggs is twice that of a male during incubation.

Seahorses won't have periods like the way humans have.

This is because, in most animals, the males transfer their sperm to fertilize the eggs of females, whereas, in seahorses, the females transfer their eggs to the male after fertilization. The reason for male seahorses bearing offspring is unknown, while some researchers believe it has something to do with shorter birthing intervals, which leads to more offspring.

According to research, female seahorses experience 'time-outs' from the reproductive cycle that are around one and half times longer than those for males.

When the female's eggs are ready, she has to deposit them quickly into the sea environment. Producing eggs and becoming pregnant are both physically draining for female seahorses, as they account for almost a third of their body weight.

Seahorse pregnancy is complex, so are other pregnancies. Male seahorses have to carry and take care of the babies until they are born. Male seahorse pregnancy tolerance is aided by genes, according to science.

Despite the fact that they are males, they become pregnant and undergo painful contractions. Female seahorses deposit their eggs in a male's brood pouch, where he fertilizes them after an elaborate courtship dance.

The male's abdomen becomes swollen as the embryo grows, just like in human pregnancy. Seahorse dads independently offer nutrients for nourishment and hormones such as prolactin. When male seahorses are ready to produce the babies, the abdomen opens and the baby seahorses are expelled by contractions.

Male Seahorse Anatomy

Male and female seahorses have distinct characteristics. Female seahorses do not have a pouch in which to lay their eggs, whereas, male seahorses do.

Male seahorses have bony bodies. They don't have scales, instead opting for a thin layer of skin stretched over a series of bone plates arranged in rings all over them. Each ring has its own number of rings.

Their bone plates armor also protects them from predators and their exterior skeleton eliminates the need for ribs. In the wild, seahorses swim upright, propelling themselves with their dorsal fin, unlike their pipefish relatives. They can develop and resorb spiky appendages depending on the environment.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for why do male seahorses give birth, then why not take a look at why do chickens lay eggs or jewel anemone facts?

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Written by Ayan Banerjee

Bachelor of Science specializing in Nautical Science

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Ayan BanerjeeBachelor of Science specializing in Nautical Science

Thanks to his degree in nautical science from T.S. Chanakya, IMU Navi Mumbai Campus, Ayan excels at producing high-quality content across a range of genres, with a strong foundation in technical writing. Ayan's contributions as an esteemed member of the editorial board of The Indian Cadet magazine and a valued member of the Chanakya Literary Committee showcase his writing skills. In his free time, Ayan stays active through sports such as badminton, table tennis, trekking, and running marathons. His passion for travel and music also inspire his writing, providing valuable insights.

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Fact-checked by Pradhanya Rao

Bachelor of Commerce specializing in Marketing and HR

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Pradhanya RaoBachelor of Commerce specializing in Marketing and HR

With a Bachelor’s degree in Commerce from Christ University, Bangalore, Pradhanya's passion for the English language and literature led her to explore the field of content writing, where she has gained extensive experience in writing, reviewing, editing, and fact-checking. She has also earned certifications in Google Ads Search, Google Ads Display, and Social Media Marketing, showcasing her proficiency in digital marketing.

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