Re:how long is thier pregnancy/mustangs

#4823
Pete Giwojna
Guest

Dear Kathy:

There are a couple of tip offs that indicate mating has occurred you should keep in mind.

First of all, when a female ripens a clutch of eggs in preparation for mating, her lower abdomen becomes noticeably swollen, particularly around the area of the vent. When she subsequently mates and passes her eggs along to the male, she may then lose up to 30% of her body weight as a result. So if you notice that one of your females has slimmed down dramatically at the same time one of the male’s pouches has become enlarged, that could be an indication of a successful egg transfer.

The other rule of thumb to keep in mind is that if a stallion’s pouch remains enlarged for more than three days in a row, there is a good chance that an egg transfer may have taken place rather than that the male is simply showing off for the females by pumping up his brood pouch and inflating it with water.

The gestation period for Mustangs (Hippocampus erectus) can be anywhere from 14-30 days, depending on water temperature and a number of other factors, but an average gestation of around 2-3 weeks at around 75°F is fairly typical.

It’s very difficult to judge how far along a pregnancy may be simply from the outward appearance and behavior of the male, Kathy. He will give some clear indications when he is experiencing labor pains and birth is imminent, as discussed below, but other than that there won’t be much warning.

Gravid males do behave somewhat differently; as their pregnancy progresses, they are less mobile and become real home bodies, since they cannot expose their developing brood to any unnecessary risks. They tend to hole up and may even go into hiding; they may go off to feed and miss a meal or two or fail to show up at the feeding station now and then.

Here are some other indications to look for that indicate mating has occurred and that the pregnancy is progressing normally:

Indications of Pregnancy.

If you witness the copulatory rise and exchange of eggs there is no doubt that mating has occurred and, knowing the date of conception, you can confidently begin the countdown toward the maternal male’s delivery date. Knowing approximately how long the gestation period will be allows plenty of time to prepare nursery tanks, set up a battery of brine shrimp hatcheries, and culture rotifers and ‘pods for the insatiable fry.

But what if you missed the big moment? How do you proceed if you missed the actual mating and transfer of eggs, and you’re not sure if you will soon be dealing with a gravid male and hordes of hungry newborns?

There are no aquatic obstetricians, underwater ultrasounds, blood tests or over-the-counter pregnancy tests to perform, and I shudder to think how one might go about collecting a urine specimen to dip! No worries. Fortunately, there are subtle signs and suggestions that indicate a pregnancy is underway. There are number of changes in the parents’ appearance and behavior to look for. For instance, the male and female will still continue to flirt, but the nature of their displays will change from full-blown courtship to regular greeting rituals.

After mating, in subsequent days the couple will continue to change colors and brighten up when in close proximity and dance together in an abbreviated version of courtship known as the Morning Greeting or Daily Greeting. The pair exhibits the same basic behaviors and maneuvers as when they were courting with one big difference — the male never "pumps" and the female does not "point."

In addition, as the pregnancy progresses, the male’s pouch darkens due to the proliferation of epithelial and connective tissue and the placenta-like changes taking place in the wall of the marsupium, and the pouch gradually swells and expands according to the number of young developing within. The latter is not always a reliable indicator, however. Inexperienced couples often spill eggs during the exchange and a male’s first few broods are often inordinately small. The brood pouch of a male that is carrying only a few fetal fry is hardly any larger than normal, and hobbyists have often been surprised by unexpected births under such circumstances.

On the other hand, an experienced male carrying a large brood can be easily distinguished by his obviously expanding pouch. These mature breeders may carry broods numbering over 1600 fetal fry, depending of course on the species. A stallion incubating hundreds of fry will have an enormously distended pouch by the time his due date approaches.

Gravid males often become increasingly reclusive and secretive as their pregnancy advances. When the onset of labor and birth is imminent, the male will begin to shows signs of distress and his respiration rate will increase to 70-80 beats per minute. The fully developed young become very active and shake loose into the lumen of the pouch shortly before delivery. In some cases, the writhing of the young can be detected through the stretched membrane of the pouch, which causes the male considerable discomfort. He may become restless and agitated as a result, swimming slowly to and fro and pacing back and forth like, well — an expectant father. The fry are usually born in the early morning hours between midnight and dawn, arriving all at once or in multiple batches 24 hours apart.

So if you happen to miss the exchange of eggs, watch closely for the following indications that mating has occurred:

(1) A change in the physical appearance of the parents. The gravid male’s pouch will change from a light opaque color to a dark brown due to the elaboration of the internal structures and thickening of the walls of the pouch. It will enlarge steadily over the next few weeks as the young grow and develop, and the aperture will change from fully dilated to a tightly closed vertical slit. The female’s trunk will change from rotund, full with ripe eggs, to noticeably shrunken and pinched in immediately after the exchange of eggs.

(2) A change in the seahorses’ courtship displays. The pair will continue to flirt and dance and brighten in coloration as part of their Daily Greetings, but the male will no longer pump (no pouch displays) and neither the female nor the male will point. The pair will make no more copulatory rises.

(3) A change in the behavior of the male. He may become increasingly shy and reclusive. Gravid males may go off their feed as the delivery date approaches, missing meals or even going into hiding. When birth is imminent, he will become agitated and distressed and his respiration will increase markedly.

When you notice these telltale signs of pregnancy, it’s time to kick your brine shrimp hatchery into high gear and start some microalgae and rotifer cultures brewing, Kathy. In the case of Mustangs, the newborns will be large enough to eat newly hatched brine shrimp (Artemia nauplii) right from birth, so you can often do without the rotifers, which are so important for newborn Hippocampus reidi and H. ingens, for example.

Delivery Day

The brood pouch enfolds, protects, aerates, osmoregulates, and nourishes the developing embryos as the male undergoes a true pregnancy (Vincent, 1990). The volume of the pouch normally increases dramatically as the pregnancy progresses. A male that is carrying a significant number of young becomes very rotund so that only a very thin layer of epithelium and connective tissue separates the interior of the pouch from the outside world by the time birth is imminent (Vincent, 1990).

The fully developed young emerge from their individual compartments and shake loose into the lumen of the pouch prior to birth (Vincent, 1990). They become very active toward the end of the pregnancy and can sometimes be seen wriggling about through the membrane of the swollen brood pouch at this time. This appears to be every bit as uncomfortable as it sounds, since expecting males become agitated and distressed as the big moment approaches. They experience definite labor pains when birth is imminent, evident as a series of powerful contractions, and soon begin pumping in time with these birth spasms in order to forcibly eject the fry from their pouches. Labor usually begins well after dark in the early morning hours (Vincent, 1990). The distraught male may pump and thrust vigorously for hours before finally ejecting the first of the newborns (Vincent, 1990). The fry are expelled singly or in ones and twos at first, but are soon spewing forth in bunches and bursts of a half dozen or more.

Delivering a large brood this way is hard work, and the exhausted male will pause periodically to recover from his exertions, gathering his strength until he is caught in the throes of another round of contractions. In some cases, it takes 2-3 days for the entire brood to be delivered in this manner.

No matter how often I see a male giving birth, it never ceases to amaze me. Watching the fry erupt into existence that way is an incredible sight. They are perfect miniature replicas of their parents, able to fend for themselves from the first. It seems a brutal beginning, a ruthlessly rude awakening, to be violently thrust into the world in such an abrupt fashion, but the newborns hit the water swimming without missing a stroke. It’s a thrill to be witnessing such a miracle of nature and always leaves me awed and exhilarated!

If you want to catch the big event, this is what Carol Cozzi-Schmarr at Ocean Rider recommends in that regard:

"In my experience, I have seen that 90% of the time the male seahorse will give birth right at the crack of dawn. For example, in one section of our hatchery we have over 50 pairs of seahorses. On any given morning if you show up just before dawn, you will witness at least 5 males giving birth at exactly the same time which is right at dawn. It is spectacular!! So, I would bet that if you set your alarm to 1 hour before sunrise you just might get lucky!! But of course, you will have to ask Mr. seahorse to be sure!!!"
Aloha, Carol

Best of luck with your Mustangs, Kathy! There certainly demonstrating a healthy interest in courtship and mating, so if your male is not already pregnant, it sounds like it will be only a matter of time before they produce their first batch of babies.

If you contact me off list ([email protected]), I will be happy to provide you with some detailed suggestions for raising newborn Mustangs, Kathy!

Happy Trails!
Pete Giwojna


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