Re:"Pregnant Male Seahorse"

Pete Giwojna

Dear Blake:

Dear Blake:

I have examined the short video clip of your seahorses and the photograph that you sent me off list carefully and I am unable to draw any firm conclusions from those materials.

I am unable to see the seahorses clearly enough in either the video or the photograph to make an exact identification, sir. To identify seahorses accurately, Blake, you need to key them out according to their meristic counts (i.e., the number of rays in their dorsal fin and pectoral fins and how many tail rings and trunk rings they have) and morphometrics (snout length proportional to the length of the head, etc.). The video and photograph are simply not detailed enough for me to attempt fin ray counts or ring counts.

However, in addition to the meristic counts and morphometrics taxonomists use to distinguish between species, there are certain other key features that are important to consider and easier to apply. For example, the seahorse’s coronet or “crown” is an important identification feature. It consists of a bony projection extending from the top of the seahorse’s head. The size and shape of the coronet are species dependent. It can be low and rounded or tall and elaborate, sometimes exaggerated to ridiculous proportions as in the Japanese species Hippocampus coronatus, in which the coronet may be taller than its head is long. In some seahorses it is almost nonexistent, nothing more than a smooth bony ridge (e.g., Hippocampus capensis and H. fuscus) and in others it is high and prickly, adorned with several distinct tines that give it a crownlike appearance (H. barbouri or H. procerus). Not only are the height and thickness of the coronet and the number of tines or projections on the crown important characters for distinguishing between species, the size and shape of the coronet may also be used to identify individual specimens, for it is said that no two coronets are exactly alike in all their details. Endless variations in the size and shape of the coronet are thought to make this feature as distinctive as human fingerprints.

The degree of spininess is another one of the keys for identifying seahorses. Hard spines form at the joints where the bony plates of the exoskeleton fuse together, adding to the seahorse’s protection by making them all the more unpalatable to predators. The degree of spinal development is extremely variable. They can be long and needle-sharp or short and dull, often being reduced to little more than blunt tabs or rounded knobs (tubercles). Some seahorses are positively bristling with long, thornlike spines, such as the Spiny Seahorse (Hippocampus histrix), the prickly Hippocampus barbouri, or the Hedgehog Seahorse (H. spinosissimus). Others are almost smooth, with rounded bumps rather than full-fledged spines (e.g., H. reidi and H. comes). It is especially important to note the disposition of the eye spines, nose spines, and cheek spines, if any, when distinguishing between species.

Using these other features, Blake, I can tell you that I can see nothing in the video or the photograph to suggest that your seahorses are not Hippocampus reidi. They are smooth bodied seahorses with relatively long snouts, they are relatively slender in the torso rather than robust or thick chested, and they have modest, rounded coronets, which are all features that are consistent with H. reidi (as well as a number of other seahorse species).

Here is a list of the meristic counts and other distinguishing features of H. reidi seahorses in case you can examine the seahorses more closely on your own and therefore determine whether they fall within these norms:

Hippocampus reidi

Meristic Counts:
Rings: 11 trunk rings + 35 tail rings (tail rings vary from 31-39).
Dorsal fin rays: 17 rays (varies from 16-19) spanning 2 trunk rings + 1 tail ring.
Pectoral fin rays: 16 soft rays (varies from 15-17).
Snout length: 2.2 (2.0-2.5) in head length. (The length of the snout fits into the length of the head only about 2 times. In others, this seahorse has a relatively long snout that measures about 1/2 the length of its head.)
Other distinctive characters:
Coronet: often low to medium and rounded, but may be quite large and convoluted (like a crumpled piece of paper).
Spines: none to low, rounded tubercles — this is a smooth-bodied seahorse.
Key Features: broad, almost double cheek and eye spines, a long, thick snout and a narrow, slender body.
Cirri: none.
Adult height: 4-7 inches (9.5-17.5cm).

Color and Pattern:

Background coloration of Hippocampus reidi is often various shades of black or brown, but this species regularly produces some of the most brilliant color morphs I have ever seen. Going from most to least common, these sports include bright yellow, orange, and red individuals. These brightly colored specimens normally retain their vivid base coloration and are much sought after by aquarists. The yellow, orange, and red morphs of H. reidi are typically found living among sponges with matching colors (Kuiter 2000).
The background color is typically covered profusely with dark brown spots, and many specimens have whitish bands or saddles across their dorso-lateral surfaces at regular intervals along their trunk and tail (Lourie, Vincent & Hall 1999). Along with the distinctive dark spots, they are often decorated with numerous tiny white dots along their tails (Lourie, Vincent & Hall 1999). In addition, males often have a prominent keel with a black line on the margin (Bull and Mitchell, 2002, p50).

These are sleek, graceful, well-proportioned animals, considered to be the loveliest of all the seahorses by many hobbyists.

Breeding Season: typically breeds year round in captivity.

Gestation Period: 14-21 days (varies with temperate and diet).

Egg Diameter: 1.2 mm.

Brood Size: very large; often 1000-2000 for large, well-fed adults.
Size at Birth: <1/4" (<6 mm).
Onset of sexual maturity: may be as early as 3-4 months but this is a slow-growing species — reproductive success is often not achieved until the age of 10 months.
Pelagic/Demersal (benthic): fry undergo a prolonged pelagic phase for their first 1-2 months.

Unfortunately, Blake, I cannot say for certain whether or not your stallion is pregnant from the video or the photograph either. He is vigorously bending and flexing his abdomen in the video, which alternately compresses and expands his brood pouch, but it is impossible to say if the seahorse is in labor and experiencing contractions or if he is merely performing pouch displays for the benefit of the female, in an effort to encourage her to mate, since the motions and the contortions that the males perform are identical in both instances.

For example, here’s some more information that discusses the "Pumping" action that males perform as part of their courtship ritual, sir:

<open quote>
Pumping and Ballooning.

Pumping and Ballooning are pouch displays performed to some extent by all male seahorses regardless of species. The energetic display known as "Pumping" is a vital part of the courtship ritual in all seahorse species that have been studied to date. Temperate and tropical seahorses alike, from the smallest pygmy ponies to the largest of the "giant" species, it appears that all male seahorses perform such pouch displays.

Pumping requires a series of coordinated movements. Bending vigorously, the aroused male jackknifes his tail to meet his trunk, thereby compressing his inflated brood pouch in the middle. The male then straightens up again, suddenly snapping back to “attention” so as to relieve the pressure on his severely compressed midsection. This rapid pumping motion has the effect of forcing water in and out of the brood pouch in a manner that is virtually identical to the way the young are expelled at birth (Vincent, 1990).

The strenuous pumping action is the stallion’s way of demonstrating his pouch is empty of eggs and that he is a strong, healthy, vigorous specimen capable of carrying countless eggs (Vincent, 1990). By so doing, he assures the female that he is ready, willing, and able to mate, and that he can successfully carry and deliver her entire brood.

Pumping is one of the final stages of courtship and it indicates the seahorses are really getting serious (Vincent, 1990). If the female is receptive, mating will take place shortly, as soon as the female hydrates her eggs, unless something intervenes in the interim.

Pumping probably serves several important functions simultaneously, making it the courting male’s method of multitasking. It is an important part of pouch preparation and certainly indicates the stallion’s readiness to breed. No doubt Pumping also provides the female with a means of judging the merits of prospective mates. She will generally favor the stud with the greatest stamina and the largest brood pouch

The energetic pumping and ballooning displays also help to prepare the male’s brood pouch for pregnancy. They flush and cleanse out the interior of the marsupium, help increase the blood supply to the lining of the pouch, and expand the elastic pouch to its fullest extent, in order to prepare it to receive a new batch of eggs. This flushing action is also believed to release special chemicals called pheromones and waft them towards the nearby female to stimulate her all the more. A growing body of evidence suggests that pumping males are thus releasing sex hormones that stimulate the female to ripen her eggs in preparation for ovulation, secure in the knowledge that a receptive male will be standing by, ready to receive them.

Courtship in many temperate and subtemperate seahorses is dominated by such pouch displays. In addition to pumping, these cold-water ponies also engage in a different type of pouch display known as “Ballooning.” This is a simple display in which they inflate their brood pouches to the fullest possible extent and parade around in front of the female in all their glory as though trying to impress her with the sheer dimensions of their pouches. The pumped up paramours perform proudly, putting on quite a show for the flirtatious fillies. (All you ladies out there are surely all too familiar with this act. No doubt you attract the same sort of attention and elicit the same type of behavior every summer at muscle beach, where all the macho men pump up their biceps, suck in their guts, and throw out their chests whenever you stroll past.)

Often all the males in the vicinity will compete for the attention of the same female, chasing after her with their pouches fully inflated this way. When all the boys are in full-blown pursuit of a female ripe with eggs, they look like a flotilla of hot air balloons racing to the finish line.

Hippocampus abdominalis, H. breviceps, and H. tuberculatus, in particular, have developed enormous pouches that are all out of proportion to their bodies when fully expanded. Their oversized pouches look like over-inflated balloons ready to burst when these stallions come a courting. Take the tiny Hippocampus breviceps, for example. With its brood pouch expanded to the maximum, a courting male looks like a fuzzy 3-inch pipe cleaner that swallowed a golf ball! Courtship in temperate/subtemperate species generally centers around pouch displays more than color changes, dancing or prancing.

Eventually, the female will respond to repeated bouts of Pumping with a display known as Pointing, thereby signaling her eagerness to rise for the exchange of eggs.
<Close quote>

So I cannot tell you if your videotape shows a male performing vigorous pouch displays and Pumping for the benefit of the nearby female, or whether they indicate that your male is in labor and preparing to deliver a brood of babies. However, I am thinking it was more likely that he is courting the female rather than pregnant, since no babies have been forthcoming and you have not seen the male "Pumping" for several days since…

However, there are a couple of tip offs that indicate mating has occurred that you can use as a rough rule of some in such situations, Blake.

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 noticeably 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.

In other words, Blake, as a first-hand observer, you are in the best position to determine whether or not your stallion may be pregnant or is just actively courting your female in an effort to become pregnant.

Yes, sir, I will be happy to provide you with information regarding how to set up the goldfish bowl kriesel nurseries, including a schematic diagram illustrating how to proceed. And I will send you a lot more information on breeding and rearing in a separate e-mail, which includes a discussion of other types of nursery tanks you can consider as well.

Best wishes with all your fishes, Blake!

Pete Giwojna

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