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The most common beasts of burden and methods of transportation of particularly the scaled mers, these majestic horses of the sea were domesticated long ago.

Basic Information


Hippocampi would appear to be half-horse, half-fish creatures. Height-wise, the generic hippocampi would stand on land just a little shorter than the average horse, but are significantly longer, with thick tails starting from halfway through the bodies and extending about a third past the regular back-length of a horse. Their forelegs are quite similar to that of a regular horse, but are a little thicker and have webbed, clawed feet instead of hooves. Their colors, special appendages, and sizes range depending on what part of the sea they are located in, but their general body structure is almost always exactly the same. The main ocean hippocampi usually range in colors of grey, blue, and green, but are rarely strong colors. They do not possess fur or a mane of hair, and instead mostly have webbed fins, usually one main one located where the mane would be, one on the back, and a few on the tail. They are covered in scales up to their necks, but their forelegs and heads are, like seahorses, covered in a thin layer of skin instead. They can swim either up and down, or side to side, and either way are exceptionally strong and fast. They have both gills and lungs, but primarily use their gills, with their lungs serving largely as a sort of swim bladder.

Genetics and Reproduction

Much like mermaids themselves, hippocampus reproduction follows a somewhat interesting set of rules. Much like the creatures called "seahorses," hippocampi have eggs, which are deposited inside a pouch the male has and fertilized internally. Upon fertilization, the eggs grow to about twice their size, and the baby hippocampi emerge fully developed (but extremely small) usually around 2 to 3 months later. About 10-20 eggs can be deposited per mating, but domesticated hippocampi rarely lay more than five in a litter, as they have been bred to have fewer than the wild hippocampi, out of whose young only about half typically survive. Though wild hippocampi babies are cared for in a herd, usually only a handful survive, especially when they are in the first stage of their life and still exceptionally small.

Growth Rate & Stages

Hippocampi are largely popped out of their father's belly fully formed, but as infants are typically blind and quite poor swimmers. The amount of time it takes for the young hippocampus to fully develop its senses and swimming strength are dependent on how well they are fed, but when fed normally, rarely takes longer than a few months' time. The hippocampus will typically grow at a somewhat steady rate until they are about 4 years of age, and they become sexually mature when their growth has mostly stopped. They live usually about 30 years. Females rarely have more than three litters in their lifetime, and wild hippocampi mate for life, though domesticated hippocampi have largely lost this trait.

Ecology and Habitats

Some type of hippocampi are native to almost any deep body of water, salt or fresh. It is rare to find them in shallower shores (though they have been known to better survive stranding than whales and dolphins because of their more sturdy forelimbs). Freshwater hippocampi are typically known to be smaller than saltwater ones, and deep sea hippocampi are known to glow and/or be completely blind.

Dietary Needs and Habits

Hippocampi are omnivorous, their diet typically consisting of seaweed, plankton, and small fish. Wild hippocampi can be active hunters, and herds will often take on much larger prey than the domesticated hippocampi typically eat. Depending on the type, some species will guard the carcass of their kill and use it as a temporary home base until its bones have been completely stripped, while others will harvest as much as they can, then return home to feed their young. It is rare for food sources in the ocean to keep easily, so food storage is relatively uncommon.

Additional Information

Social Structure

Domestic hippocampi largely have not been observed to form any particular type of special social structure, though they display quite the capacity to form loyal relationships with one another. The wild hippocampi, however, rely on a more definite command structure, thanks to their more active hunting life. Usually the strongest male of the herd will be treated as general leader and protector of the herd, while 1-3 females are kept in rotation for the caring of the young. The head of the herd is sometimes challenged by younger males who are part of the herd, and these occasionally result in death matches, but it is not common for males to sabotage or kick out the younger males of the herd. On occasion, two leaders will emerge in a herd, one who leads the hunt, one who protects the herd. This case is fairly rare, and largely occurs when one hippocampus turns out to be a better strategic hunter despite not being the strongest, and this being the case, the hunt leader can also sometimes be female.


Hippocampi have been domesticated for so long, that it is rare for it to be attempted to tame wild hippocampi. It is extremely difficult to tame a wild hippocampus, as it usually requires one be isolated from the herd. If found as a baby, it is relatively easy, but with a fully grown adult found by itself in the wild, the mer in question would need to genuinely establish a relationship of trust to even begin the process, and even after "taming," it is not unlikely for the hippocampus to grow dissatisfied with a new lifestyle and return to a herd life.

Uses, Products & Exploitation

Hippocampi are used as almost anything in mer society, but most commonly as beasts of burden, methods of transportation, and sometimes as almost hunting dogs. Depending on the nature of the society, some can be used to guard specific items or people as well, but can also be eventually consumed.

Average Intelligence

Hippocampi, both wild and domesticated, are known to be extremely intelligent and easily taught (though not necessarily obedient). They do not understand speech, but appear to be acute judges of character and readers of body language. The wild hippocampi are known to be better problem solvers, however.

Perception and Sensory Capabilities

Mers would not consider hippocampi to have special senses, but their vision and hearing even in deep, murky waters is exceptional. They do not, however, have much of a sense of smell, though they do have regular nares (fish nostrils). The wild kind have retained their excellent sense of smell and have slightly larger nares, that can work even when they are immobile by pumping water through.

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