Are seahorses fish?

Yes! They might not look like fish at first glance, but they certainly are fish. Seahorses are actually close relatives of familiar fish such as tuna and trout. If you were to stretch a seahorse out and lie it on its stomach, it would be easier to see that they have a lot of physical traits in common with other fish. They belong to the class Actinopterygii (bony fish), which includes salmon and swordfish, and the family Syngnathidae (fused-jawed fish), which includes pipefish and seadragons. All seahorses belong to the genus Hippocampus, a combination of the Greek words for “horse” and “sea monster”.

 
 
 

How many different seahorses are there?

There are 44 seahorse species. For now, at least! Scientists don’t all agree on this number. In the future, this number could go up or down as more types are discovered, or if seahorses which look quite different from each other are found to belong to the same species.

 

What do they look like?

Parts of a seahorse.  Adapted from Lourie et al, 2004.

Parts of a seahorse. Adapted from Lourie et al, 2004.

Seahorses are quite bizarre creatures! They are fish, but they have a horse-like head, a monkey-like tail and a kangaroo-like pouch. They have a few things in common with chameleons as well - they can move their eyes around, and change their skin colour! Seahorses can even grow bits of skin that look like seaweed to help them hide better. And yes, they have skin, not scales! Their skin is stretched over bony armour, and they often have spines all over their body. The group of spines on the top of their head is called a coronet, which looks like a crown. The best way to tell boy seahorses and girl seahorses apart is whether or not they have a big pocket on their belly for carrying babies - only the dads have these!

 

How big are they?

Seahorse heights are measured from the tips of their curly tails to the tops of their bony heads. Depending on the type of seahorse, they can be more than 30 cm tall (bigger than a shoe!) or less than 2 cm tall (smaller than a strawberry!).

 

Do seahorses make sounds?

Seahorses growl, click and purr! They often make noise when eating or greeting their mate.

 

Where do they live?

They live all over the world in parts of the ocean that aren’t too deep or too cold. You can also find seahorses in “estuaries” - places where salty ocean water meets fresh river water. You can find them in seagrass beds, mangrove forests, coral reefs and other shallow coastal habitats. Humans often pollute and destroy shallow coastal habitats, which can be a big problem for seahorses.

Areas with blue shading are where seahorses live. ( Source: Riley Pollom/Project Seahorse )

Areas with blue shading are where seahorses live. (Source: Riley Pollom/Project Seahorse)

 

How long do they live?

Scientists don’t know very much about how long wild seahorses live. When they are kept in aquariums, they live about one to five years, depending on the type of seahorse. Larger seahorses tend to live longer than smaller ones do.

What, how, and how much do they eat?

Thorny seahorse ( Hippocampus histrix ).  Photo by Mark Birt /Guylian Seahorses of the World

Thorny seahorse (Hippocampus histrix). Photo by Mark Birt /Guylian Seahorses of the World

Seahorses have no stomach or teeth. That sounds like a pretty big problem, right? How do they eat?! Well, instead of a mouth that opens and closes like ours, they have a tube for a snout, which they use to suck in all their food like a vacuum. Can you imagine if you could just vacuum up cheeseburgers with your mouth?! They eat pretty much anything small enough to fit through their mouth, which is mainly shrimp-like creatures, baby fish, and other small organisms.

They are slow swimmers and don’t chase their prey, relying on sneak-attacks to catch a meal - so they are known as ambush predators.  Because they don’t have stomachs, they have to constantly eat. They eat between a tenth to a quarter of their body weight every day. That’s a LOT!

 

What eats them?

Seahorses are slow swimmers, but luckily they are excellent at hide-and-seek! This means that it isn’t easy for other animals to find and eat them. Not only are they difficult to spot, but they’re also pretty crunchy. However, they can be eaten by big fish like tuna, and are also known to be eaten by rays, penguins, crabs, sea turtles and seabirds. Baby seahorses are more likely to be eaten than adults. In many seahorse species, humans are bigger threats to seahorses than marine carnivores are.

Yellow-legged Gull ( Lars michachellis ) munching on a short-snouted seahorse ( H. hippocampus). Photo courtesy of Marina Gorbunova/iNaturalist.

Yellow-legged Gull (Lars michachellis) munching on a short-snouted seahorse (H. hippocampus). Photo courtesy of Marina Gorbunova/iNaturalist.

 

How do they swim?

Seahorses aren’t very fast swimmers, and they have less fins than most adult fishes do. They mostly use the tiny fin on their back to power themselves through the water, and steer with the fins on their sides. They mainly like to stay in one place by wrapping their tails around things like coral and seaweed to hold on.

 

How long is the pregnancy and how big are the young?

Male seahorses are pregnant for about two weeks to a month. They usually give birth at night, and it can take them hours to do so. One male seahorse can give birth to around 100-200 babies (sometimes even more)! Baby seahorses look quite a lot like their parents, just much, much smaller. Once the babies are born, they float off and are ready to face the ocean on their own.

Watch a male seahorse giving birth to hundreds of seahorses.
Video by Meagan Abele/Project Seahorse

 

Why aren’t the boys called girls?

If the boy seahorse gets pregnant, why isn’t it called a girl seahorse? This is because males (boys) and females (girls) are based on who makes the sperm and who makes the egg, not on who carries the babies. The female puts her eggs in the male’s pouch, then the male fertilizes them. The male’s pouch is quite similar to a human mother’s womb. The pouch provides the baby seahorses with oxygen and nutrients. Right before they are born, the fluid inside the pouch is very similar to seawater, which makes it easier for them to adapt to their new life in the ocean.

 

Do they really mate for life?

Yes! Not all species do, but many seahorses stay with the same partner for one or more breeding seasons. When an animal only has one mate, it is called monogamy. In the mornings, partner seahorses may say “Good morning!” by changing colour and dancing together for several minutes, then parting to go about their day!

Hippocampus jayakari  pair.  Photo by Amir Abramovich/Guylian Seahorses of the World

Hippocampus jayakari pair. Photo by Amir Abramovich/Guylian Seahorses of the World

 

What is the conservation status of the seahorse?

Seahorse behaviour and ecology makes them very vulnerable. According to the IUCN (International Union for Conservation of Nature) Red List of Threatened Species, 12 of the 42 seahorse species are listed as Vulnerable to extinction, and two species, the Knysna seahorse and White’s seahorse, are Endangered.  Many of them are Data Deficient, which means that they might be Vulnerable or Endangered, but not enough research has been done yet to know for sure. For more information about the IUCN Red List, see www.iucnredlist.org.

 

What threatens seahorses?

Along with the loss of their habitat, seahorses are caught live for aquariums, and killed for use in Traditional Chinese Medicine and other traditional medicine. They are also dried for use as souvenirs such as paperweights and jewellery, and eaten by humans (usually as a tonic, rather than a snack - they aren’t particularly tasty and are quite bony). One of the biggest threats to seahorses is the fact that they often caught accidentally in fishing nets meant for catching shrimp.

A Pacific seahorse ( Hippocampus ingens ) lies among the catch of a commercial shrimp trawler in the Southern Gulf of California, Mexico.  Photo by Sarah Foster/Project Seahorse

A Pacific seahorse (Hippocampus ingens) lies among the catch of a commercial shrimp trawler in the Southern Gulf of California, Mexico. Photo by Sarah Foster/Project Seahorse

 

Which countries trade seahorses?

Seahorse trade happens on every continent. Except Antarctica, of course! Here is a list of countries and territories that have been known to trade seahorses at some point after 1996:

Africa: Cameroon, Cote d’Ivoire, Egypt, Gambia, Guinea, Kenya, Madagascar, Mauritania, Mauritius, Mozambique, Namibia, Nigeria, Senegal, Seychelles, South Africa, Swaziland, Tanzania, Togo

Asia: Bangladesh, Brunei Darussalam, Cambodia, People’s Republic of China, Hong Kong SAR, India, Indonesia, Japan, Korea, Republic of, Lao People’s Democratic Republic, Macau, Malaysia, Maldives, Myanmar, Pakistan, Philippines, Singapore, Sri Lanka, Taiwan (province of China), Thailand, Viet Nam

Europe: Austria, Belgium, Czech Republic, Denmark, France, Germany, Greece, Hungary, Ireland, Italy, Monaco, Netherlands, Norway, Poland, Portugal, Romania, Spain, Sweden, Switzerland, Ukraine, United Kingdom

Middle East: Israel, Jordan, Kuwait, Saudi Arabia, United Arab Emirates

North and Central America and the Caribbean: Bahamas, Barbados, Belize, Canada, Costa Rica, Cuba, Dominican Republic, Guam, Guatemala, Haiti, Honduras, Mexico, Nicaragua, Panama, USA

South America: Argentina, Bolivia, Brazil, Chile, Ecuador, Peru, Suriname, Uruguay, Venezuela

Oceania: Australia, Fiji, New Caledonia, New Zealand, Solomon Islands, Vanuatu

The largest exporter of seahorses appears to be Thailand, followed by Guinea and Senegal. Most dead seahorses are probably imported to mainland China, Taiwan (Province of China) and Hong Kong SAR, while the U.S.A. is the largest reported importer of live seahorses.

 

How are seahorses used in traditional Chinese medicine (TCM)?

Seahorses have been a part of Traditional Chinese Medicine (TCM) for over 600 years! They are used in the treatment of lots of different health issues, including asthma, heart disease and skin conditions. TCM is recognized by the World Health Organization (WHO) as a valid form of healthcare. It is not a matter of whether medicine made from seahorses actually works - it is about getting people to consume seahorses in moderation, in order to lessen the pressure on their wild populations.

Dried seahorses for sale in a market in Hong Kong.  Photo by Tyler Stiem/Project Seahorse.

Dried seahorses for sale in a market in Hong Kong. Photo by Tyler Stiem/Project Seahorse.

 
 
 

How can we save seahorses?

 

Project Seahorse is the IUCN global authority on seahorses and their relatives. Led by award-winning scientists Prof. Amanda Vincent and Dr. Heather Koldewey, we pioneered the study and conservation of seahorses and continue to lead the push to protect these important animals. 

Biological research

Project Seahorse researchers were the first to study seahorses underwater and the first to publish a species identification guide. We continue to publish the bulk of new research on the biology and conservation of seahorses.

Trade and policy work

In the mid 1990's, Project Seahorse uncovered vast global trade in seahorses, and in 2002 we helped achieve landmark trade protections for seahorses under CITES. We work tirelessly to strengthen national and international conservation policy, helping governments to ensure their seahorse trade is sustainable.

Citizen science and conservation

Through iSeahorse, our pioneering citizen science program, we're increasing the number of people studying seahorses and advocating for their protection from fewer than twenty to over a thousand. Our goal is to build a global early warning system for at-risk seahorse populations and habitats.

Learn more about how YOU can be involved here

SUCCESS BY THE NUMBERS

2002

The year Project Seahorse achieved landmark CITES trade protections for seahorses
 

1000+

Seahorse citizen scientists and conservationists we've recruited since 2013
 

10

Seahorse population monitoring projects we've established through iSeahorse
 

Six

Shark and ray species we've helped protect through our seahorse trade work 

 

 
 
 
 

How should I interact with seahorses?

 

When you see a seahorse, do not touch it!
This damages the protective mucus on the seahorse’s skin that prevents bacterial infections and other diseases.

Don’t stir up silt with your feet or fins.
This makes it hard to find seahorses and you may injure animals with your feet. If you’re walking, always watch where you step.

Limit the number of photographs taken per seahorse per dive (5 or less).
Refer to the Project AWARE Guidelines for underwater photography for more photography tips.

No seahorse should be moved or encouraged to move, ever.
It is common to find seahorses lying motionless on the seafloor. Leave them be.

For more tips refer to Dr Richard Smith's Code of Conduct for taking photographs of seahorses.