The Times Australia
The Times World News

.

Pregnant male seahorses support up to 1,000 growing babies by forming a placenta

  • Written by Jessica Suzanne Dudley, Postdoctoral Fellow, Macquarie University

Supplying oxygen to their growing offspring and removing carbon dioxide is a major challenge for every pregnant animal. Humans deal with this problem by developing a placenta, but in seahorses — where the male, not the female, gestates and gives birth to the young — exactly how it worked hasn’t always been so clear.

Male seahorses incubate their embryos inside a pouch, and until now it was unclear how the embryos “breathe” inside this closed structure. Our new study, published in the journal Placenta[1], examines how pregnant male seahorses (Hippocampus abdominalis) provide oxygen supply and carbon dioxide removal to their embryos.

We examined male seahorse pouches under the microscope at different stages of pregnancy, and found they develop complex placental structures over time — in similar ways to human pregnancy.

Pregnant male seahorses support up to 1,000 growing babies by forming a placenta Male pot-bellied seahorses have large fleshy pouches where embryos develop during pregnancy. by Aaron Gustafson

Read more: Curious Kids: Is it true that male seahorses give birth?[2]

A pregnant dad gestating up to 1,000 babies

Male pregnancy is rare, only occurring in a group of fish that includes seahorses, seadragons, pipehorses and pipefishes.

Pot-bellied seahorse males have a specialised enclosed structure on their tail. This organ is called the brood pouch, in which the embryos develop[3].

The female deposits eggs into the male’s pouch after a mating dance[4] and pregnancy lasts about 30 days[5].

While inside the pouch, the male supplies nutrients[6] to his developing embryos, before giving birth[7] to up to 1,000 babies.

Pregnant male seahorses support up to 1,000 growing babies by forming a placenta Male pot-bellied seahorse filling his pouch with water in a mating display. by Kymberlie R. McGuire

Embryonic development requires oxygen, and the oxygen demand increases as the embryo grows. So too does the need to get rid of the resulting carbon dioxide efficiently. This presents a problem for the pregnant male seahorse.

Enter the placenta

In egg-laying animals — such as birds, monotremes[8], certain reptiles and fishes — the growing embryo accesses oxygen and gets rid of carbon dioxide through pores in the egg shell.

For animals that give birth to live young, a different solution is required. Pregnant humans develop a placenta, a complex organ connecting the mother to her developing baby, which allows an efficient exchange of oxygen and carbon dioxide (it also gets nutrients to the baby, and removes waste, via the bloodstream).

Placentae are filled with many small blood vessels and often there is a thinning of the tissue layers that separate the parent’s and baby’s blood circulations. This improves the efficiency of oxygen and nutrient delivery to the fetus.

Surprisingly, the placenta is not unique to mammals.

Some sharks, like the Australian sharpnose shark (Rhizoprionodon taylori) develop a placenta[9] with an umbilical cord joining the mother to her babies during pregnancy. Many live-bearing lizards form a placenta[10] (including very complex ones[11]) to provide respiratory gases and some nutrients to their developing embryos.

Our previous research[12] identified genes that allow the seahorse father to provide for the developing embryos while inside his pouch.

Our new study[13] shows that during pregnancy the pouch undergoes many changes similar to those seen in mammalian pregnancy. We focused on examining the brood pouch of male seahorses during pregnancy to determine exactly how they provide oxygen to their developing embryos.

A Pot-belly seahorse (Hippocampus abdominalis) floats in water By viewing the seahorse pouch under the microscope at various stages of pregnancy, we found that small blood vessels grow within the pouch. Shutterstock

What we found

By viewing the seahorse pouch under the microscope at various stages of pregnancy, we found that small blood vessels grow within the pouch, particularly towards the end of pregnancy. This is when the baby seahorses (called fry) require the most oxygen.

The distance between the father’s blood supply and the embryos also decreases dramatically as the pregnancy goes on. These changes improve the efficiency of transport between the father and the embryos.

Interestingly, many of the changes that occur in the seahorse pouch during pregnancy are similar to those that occur in the uterus during mammalian pregnancy.

We have only scratched the surface of understanding the function of the seahorse placenta during pregnancy.

There is still much to learn about how these fathers protect and nourish their babies during pregnancy — but our work shows the morphological changes to seahorse brood pouches have a lot in common with the development of mammalian placentae.

Read more: The secret sex life and pregnancy of a seahorse dad[14]

References

  1. ^ Placenta (www.sciencedirect.com)
  2. ^ Curious Kids: Is it true that male seahorses give birth? (theconversation.com)
  3. ^ embryos develop (theconversation.com)
  4. ^ mating dance (www.youtube.com)
  5. ^ 30 days (onlinelibrary.wiley.com)
  6. ^ supplies nutrients (pubmed.ncbi.nlm.nih.gov)
  7. ^ giving birth (www.youtube.com)
  8. ^ monotremes (www.theguardian.com)
  9. ^ develop a placenta (pubmed.ncbi.nlm.nih.gov)
  10. ^ live-bearing lizards form a placenta (pubmed.ncbi.nlm.nih.gov)
  11. ^ ones (www.discovermagazine.com)
  12. ^ research (pubmed.ncbi.nlm.nih.gov)
  13. ^ study (www.sciencedirect.com)
  14. ^ The secret sex life and pregnancy of a seahorse dad (theconversation.com)

Read more https://theconversation.com/pregnant-male-seahorses-support-up-to-1-000-growing-babies-by-forming-a-placenta-167534

Times Magazine

Headless CMS in Digital Twins and 3D Product Experiences

Image by freepik As the metaverse becomes more advanced and accessible, it's clear that multiple sectors will use digital twins and 3D product experiences to visualize, connect, and streamline efforts better. A digital twin is a virtual replica of ...

The Decline of Hyper-Casual: How Mid-Core Mobile Games Took Over in 2025

In recent years, the mobile gaming landscape has undergone a significant transformation, with mid-core mobile games emerging as the dominant force in app stores by 2025. This shift is underpinned by changing user habits and evolving monetization tr...

Understanding ITIL 4 and PRINCE2 Project Management Synergy

Key Highlights ITIL 4 focuses on IT service management, emphasising continual improvement and value creation through modern digital transformation approaches. PRINCE2 project management supports systematic planning and execution of projects wit...

What AI Adoption Means for the Future of Workplace Risk Management

Image by freepik As industrial operations become more complex and fast-paced, the risks faced by workers and employers alike continue to grow. Traditional safety models—reliant on manual oversight, reactive investigations, and standardised checklist...

From Beach Bops to Alpine Anthems: Your Sonos Survival Guide for a Long Weekend Escape

Alright, fellow adventurers and relaxation enthusiasts! So, you've packed your bags, charged your devices, and mentally prepared for that glorious King's Birthday long weekend. But hold on, are you really ready? Because a true long weekend warrior kn...

Effective Commercial Pest Control Solutions for a Safer Workplace

Keeping a workplace clean, safe, and free from pests is essential for maintaining productivity, protecting employee health, and upholding a company's reputation. Pests pose health risks, can cause structural damage, and can lead to serious legal an...

The Times Features

Duke of Dural to Get Rooftop Bar as New Owners Invest in Venue Upgrade

The Duke of Dural, in Sydney’s north-west, is set for a major uplift under new ownership, following its acquisition by hospitality group Good Beer Company this week. Led by resp...

Prefab’s Second Life: Why Australia’s Backyard Boom Needs a Circular Makeover

The humble granny flat is being reimagined not just as a fix for housing shortages, but as a cornerstone of circular, factory-built architecture. But are our systems ready to s...

Melbourne’s Burglary Boom: Break-Ins Surge Nearly 25%

Victorian homeowners are being warned to act now, as rising break-ins and falling arrest rates paint a worrying picture for suburban safety. Melbourne residents are facing an ...

Exploring the Curriculum at a Modern Junior School in Melbourne

Key Highlights The curriculum at junior schools emphasises whole-person development, catering to children’s physical, emotional, and intellectual needs. It ensures early year...

Distressed by all the bad news? Here’s how to stay informed but still look after yourself

If you’re feeling like the news is particularly bad at the moment, you’re not alone. But many of us can’t look away – and don’t want to. Engaging with news can help us make ...

The Role of Your GP in Creating a Chronic Disease Management Plan That Works

Living with a long-term condition, whether that is diabetes, asthma, arthritis or heart disease, means making hundreds of small decisions every day. You plan your diet against m...