Have you ever watched seahorses courting? Most people know that seahorses break the conventional rules in breeding, in that the male carries and births the fry. There are some animal species in which the male plays a larger role in protecting the young, such as male penguins who go without eating for months in order to keep their egg incubated and warm. But this unique role reversal in actual pregnancy seems limited to members of the Syngnathidae family of fish, water bugs and toads. While this fascinates many and sets seahorses apart from other fish and animals, the seahorses' behavior before the pregnancy is also intriguing and entertaining. In fact, to an inexperienced observer or new keeper, some of the behaviors can even seem frightening!
I was extremely worried the first time I watched all of the color instantly vanish from my beloved seahorses. I was sure there must be something wrong when they began oddly bending sideways at the “waist” to head butt each other. Frantically, I called my mentor and breeder friends begging for help, assuming that this was a symptom of illness. They tried not to laugh at me and explained that this was the start of the odd, yet fascinating courting behavior of seahorses. Many articles cover the male pregnancy itself, but I have not seen many that describe the process they go through in picking a partner. After a few years of breeding seahorses myself, I am quite used to the way seahorses interact with each other, and thought I would share some of my observations. You can look through some of my pictures and read my observations by clicking HERE.
As a change of pace from the normal educational articles, I wanted to try to something different with this subject. So, the following is my attempt at humor in comparing seahorse courting behaviors to movies clips that depict humans acting in similar fashions. My observations of these behaviors are limited to the seahorse species’ I have personally kept and bred, so other seahorses might not act in the same ways. Many times in fact, my seahorses do not fit the theories scientists have suggested about seahorse breeding behavior. So, I am merely sharing personal observations (not scientific in any way), but I would bet after reading this you will begin to notice these things in your own seahorses. Keep in mind this is mostly satire, with enough truth to be worth reading.
The "how" and "when" of sexing a seahorse!
Seahorses reach sexual maturity between 4-6 months of age, at which time a male forms a pouch in the area between anal fin and tail, and a female's ovipositor becomes more pronounce. The ovipositor is the female organ that she uses to release eggs into the opening of a male's pouch. According to an analysis published in Molecular Biology and Evolution, the male pouch "provides protection, gas exchange, osmoregulation, and limited nutrient provisioning to developing embryos". Once a seahorse has developed his or her reproductive parts, it becomes easier to determine whether it is male or female by looking for a pouch.
Sexing younger seahorses can still be difficult, because some male seahorses refuse to be labeled, or for whatever reason, do not visibly grow their pouch until much later. These males, referred to as "late bloomers" can develop a pouch as late as 9 months old.
Prior to these physical changes, the seahorses in a species all look very similar and do not behave much differently from one another. However, the moment a dark spot forms between the tail and anal fin indicating that a pouch is growing, the behaviors between the sexes begin to change also. For lack of better term, they seem to “hit puberty”.
All of a sudden, the males do a lot more wrestling with each other and begin to notice and want to impress females. The term “displaying” is used to describe the way a male will stick his chest out, making him seem to stand a bit taller, and literally pose in front of other seahorses.
The picture above shows a "late blooming" hybrid. On the left, a picture of a female ovipositor up close. On the right, a young male displaying.
Interestingly, the sex of the other seahorses does not seem to make much difference in displaying, as the male just appears to want all others to behold his greatness. This reminds me a lot of a couple human men I know, but that’s a different story.
Boys will be boys?
Another interesting male behavior that begins around the same time that they notice the “ladies” is “nonchalant displaying” (I made this one up, but it fits). The male will position himself right in front of a female, turn his back to her, get into his displaying stance, and then pretend he does not know she is there. This is extremely amusing to watch from the outside, but I do wish I could somehow know what these fascinating fish are thinking. Based on their expressions, I could certainly make a few educated guesses! The following clip shows my male Hippocampus reidi nonchalantly displaying for his female, who looks like she is quite egg filled. (You’ll have to excuse my silly commentary).
When a male is not pretending to ignore his conquest, he will become aggressively attentive. Many times, I have observed a male flushing and ballooning his pouch right in a female's face. Flushing describes the male bending at the midsection, pulling water into his pouch, and then straightening up quickly to release the water.....in the same way as he will release fry during labor. Ballooning is even more comical, as the male literally inflates his pouch to it's largest size, which resembles blowing up a balloon so much it became the title of the action. These forms of displaying are normal, but the insistent way the male will continue to move right in front of the female, as if saying "this is a nice pouch isn't it???" very much reminds me of the inappropriate pictures many human males will send to ladies who never requested them. (I debated, but decided that doing a comparison video of this might get me put in jail....so we'll settle for a picture :))
The females' behaviors also changes around this time. Whether it is in response to the males’ new attitudes or due to their own maturing process, I cannot be sure. However, in most of the females I have raised, they go from rambunctious young seahorses, to more subdued and observant adults. Watching their slower, more deliberate movements in comparison to that of the males reminds me of watching a cat and mouse interaction. While the males swim around displaying and showing off their adult physique, the females seem less interested in other seahorses and will literally seem to try to avoid an aggressive male. Yet, within a few days, she will look round and egg filled. At first I wondered if maybe the female seahorse's own body betrayed her? Why would she seem so uninterested, yet make eggs? According to Seahorse.com, "there is a growing body of evidence that suggests pumping males are releasing sex hormones that stimulate the female to ripen her eggs in preparation for ovulation". Now this I can believe! Maybe it really is a game of manipulation.....or maybe I should really stop pretending that seahorses have the ability to feel emotions the way humans do? Ah well, this would be a much less funny article without the comparisons, so let us continue!
Even if I do not see the beginning of the courting process, I can always tell when a female has eggs. Aside from the obvious fact that she gets more round in the stomach, the males act as if they can smell her “condition” through the water. The moment I turn the lights on, the males enter into “get the girl with the eggs” mode, and it becomes almost more important than food to them.
For a very long time scientists believed that seahorses were monogamous. The first studies on seahorses portrayed lovers who would never take another mate if they lost their partner, rocking the world with this tale of forever romance. Indeed, some species do stay with their original partners, at least through a breeding season. However, I think that the studies got a few details wrong. First, I have personally seen my largest male carry the fry of 5 different females. While this may be directly related to the confined space, more competition and more candidates within my aquarium, the bottom line is that I have seen my seahorses switch partners multiple times. They will often return to the same mate for a period of time, but I believe that is more out of convenience than anything else. My thoughts are that the courting behaviors and rituals that continue throughout the pregnancy, such as the male displaying and daily dances cause the female to make more eggs at the exact time that the male will have given birth and be ready to receive the new batch. They also will be more familiar with the other’s movements and abilities, which might just be a bad thing, depending on how they performed? I’ve certainly regretted a few partners, so why couldn’t seahorses?
The belief that male seahorses will prefer the largest female seahorse, reasoning that the larger females will make a larger amount of healthier eggs, might be true initially. But the males continue competing over ALL females, no matter what connections were made prior. The “bond” described by scientists as forming between a “pair” does not stop every male in the tank from trying to steal the eggs anyways. They act as if they will do anything to get those eggs, and are not above snipping at other males, using their size to bully competitors and coerce the female into submission, and even going so far as to attempt to slide in and literally steal the eggs at the last moment. Maybe I just have very rude seahorses, but none of my pairs’ have the romantic times described in national geographic.
As a female starts looking more round in the stomach area, she seems to completely change her mind and attitude for a second time. She begins looking for the chosen male every day (and typically must roll her eyes when she finds him nonchalantly displaying). Once he acknowledges her, they spend some time swimming with locked tails or practicing for the exchange by dancing together. The male continues to use the same forms of displaying to show the female how wise she was to choose such a beast of a seahorse.
After anywhere from a few hours to a few days, the female's “I’m not interested” attitude changes for a third time, turning into a quite demanding insistence that her male take the eggs! The second common belief that I disagree with based on observation of my own seahorses is that the male chooses his female mate. The male’s more aggressive role in pushing for reproduction and male competition in general might determine who "gets the girl" initially, but if the female did not make the eggs, there would be no fry for the male to carry. So much emphasis is placed on the male fertilizing and carrying the eggs, that most people forget that the female has no easy task in making the eggs. The eggs take up 1/3 of the female's body weight and require a lot of her nutrition. After releasing the eggs, a female will look as if she hasn't eaten for week, which might be somewhat true if she is giving up most of it to make eggs. I do not know the exact scientific process the female must go through to make her eggs, but I have many female seahorses who do not eat very much, get darker in color, and stay hidden for a day or so before an egg exchange. If I had to guess, I would say that making eggs is a bigger deal than we imagine.
So, all of the macho male behavior is likely an effort to convince her just to make the eggs, in addition to who will best carry them. In the end, it seems to me that it is the female who will choose a worthy male out of all competitors, make eggs for him, and then give them to him alone. This theory is supported by the many times that I have seen a female choose to expel the eggs versus give them to a male that she did not choose. In the following video, the female sits nodding to her chosen male to begin their dance, but he has already taken the eggs from another. Instead of giving her eggs to another male, she spilled them on the floor, and did not make any more for quite some time.
I might read too much into these behaviors, but I also have a lot of fun with my under the sea soap opera. Either way, after the female is filled with eggs, the cat and mouse game comes full circle. The female will act extremely different in how she responds to her mate and will appear to be the more aggressive partner. Personally, I think that the reason for all of the male’s ballooning, flushing and displaying is that the female still makes all final decisions and reserves the right to say “no”. Once she has made her choice however, she depends on the male to do the difficult work of nourishing the fry until birth.
"Us against the world"?
When the female is ready to give the male her eggs, she will give him the nod. The nod is exactly as it sounds: the female points her snout toward the surface, telling the male that his time has come to be a father. In addition to other male interruptions, the seahorse pair must also line up perfectly to complete the exchange. With no arms to steady themselves and flow causing ripples in their attempt to connect, the two will begin to swim around each other in a circular pattern, using the move to pull themselves into perfect alignment with each other as they spin towards the surface. If they do not connect perfectly, and the female's ovipositor is not positioned precisely at the opening of the male's pouch, the eggs will end up on the floor instead of becoming fry.
After many practice runs, if the male and female make their connection, the eggs are released into the male’s pouch. As they enter the pouch, the eggs are fertilized by the male’s sperm. Over the next 14-30 days, the male regulates the temperature and salinity of the water surrounding the eggs, provides nutrition to the growing embryos and protects them as they become tiny new seahorses.
To any potential breeder, enthusiastic keeper or even curious hobbyist: Do not despair if the seahorses miss their mark on their first attempt at reproduction, spilling eggs onto the floor instead. The seahorses just need more practice! They will amaze you with their ability to line up perfectly in less time each try. The fry will seem bigger and more healthy as the seahorses breed more also. After a few pregnancies, the females will get larger in size themselves and begin creating more eggs. The male’s pouch will become more flexible and he will get better at providing nourishment to the eggs. No keeper should feel badly if their pairs’ first attempt at reproduction is not perfect, as the parents must practice to make perfect little offspring. Instead, enjoy this awesome display of behaviors that begs the question “are you sure they do not think like humans?”
I’ll show you what happens next in a follow up article, but I want to hear your opinions! Do you think the male or female gets to choose their partner? Do your seahorses always choose the same partner? Have you noticed any of these behaviors in your seahorses? Do you want more information and articles about raising fry?
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