Re:Strange behaviour

#4559
Pete Giwojna
Guest

Dear Jake:

Okay, that sounds good. If the head and face of the seahorse retain their normal coloration when the seahorse lightens up or "brightens" in coloration, then he is very likely performing courtship displays for the benefit of the female. If and when the female is receptive towards his advances, you will have an opportunity to witness some fascinating social interactions in the days and weeks ahead, sir.

Researchers have identified and named seven distinct courtship displays seahorses commonly engage in when pairing off to mate, which I have summarized below. These descriptions should give you a better idea of what the mating dance and other courtship displays look like:

1) Brightening
2) Tilting, which leads to Reciprocal Quivering
3) Dancing: Carouseling and the Maypole Dance
4) Parallel Promenade
5) Pouch Displays: Pumping and Ballooning
6) Pointing
7) Copulatory Rise

Brightening, pouch displays, pointing and rising are seen universally throughout the genus Hippocampus, but there is some variation between tropical and temperate species as well as between dwarf varieties and the larger breeds or greater seahorses. Tropical species tend to exhibit more dramatic color changes during courtship while temperate species often rely more on pouch displays. Dwarf seahorses generally do less dancing and more quivering than the larger breeds, whereas many of the greater seahorses dance their tails off but rarely ever shimmy. Courtship is relatively abbreviated in polygamous seahorses and rather protracted in species that bond strongly, often lasting for a period of 3-4 days during initial pair formation. The terminology researchers use to designate these displays may be unfamiliar at first, but experienced seahorse keepers will immediately recognize the behaviors they describe.

Not every pair of courting seahorses will exhibit all of the displays listed below, but ALL seahorses will demonstrate most of these displays during courtship:

Approaching and Brightening.

This is a very basic display that is seen throughout every phase of courtship. When a seahorse that is ready to mate spots a prospective partner, it will move closer to the other seahorse while maintaining a characteristic posture and signal its intentions by changing in coloration (Vincent, 1990). It will hold its body stiffly erect and brighten up as it approaches (Vincent, 1990). If the other seahorse is uninterested, it will either move away or remain unresponsive, retaining its normal color. But if the other seahorse is receptive and is impressed by what it sees, it will allow the newcomer to move within touching distance and indicate its interest by brightening in return. Either sex may initiate courtship by approaching and brightening this way (Vincent, 1990).

Courtship in the wild is ordinarily conducted in the twilight hours of early morning in the wild. Courting begins with the partners approaching and brightening and ends when they move apart and resume their normal drab coloration again. There will be many such bouts of intense courtship over a period of days during the initial pair formation. Captive-bred seahorses often court more or less constantly and frequently continue courting throughout the day rather than confining themselves to the dawn displays typical of their wild conspecifics. This may simply be a response to a predator-free environment in which it is safe to remain bright and conspicuous regardless of the lighting conditions.

Courtship coloration varies from species to species. However, regardless of the colors involved, the head, dorsal surface (i.e., back), and ventral line (keel) of the seahorse normally remain quite dark while the rest of the body becomes lighter and dramatically intensifies in color (Vincent, 1990). Seahorses flaunt their brilliant coloration in order to impress prospective mates and the overall effect of this change is to make the seahorse much more conspicuous (Giwojna, Mar. 2002

As a general rule, tropical seahorses often undergo more pronounced color changes than temperate species, which tend to be more subdued. Dwarf seahorses (Hippocampus zosterae) are not nearly as bright and flashy during courtship than their bigger brethren. These elfin creatures take on a different sort of glow. They sparkle looking as if they have been sprinkled with glitter, as they take on metallic tints, hues and highlights of their natural neutral colors. Tropical seahorse species generally rely on brightening and conspicuous color changes during courtship more than their temperate counterparts, which depend primarily on pouch displays such as Ballooning.

If all goes well during the approaching and brightening phase, the seahorses usually arrange themselves side by side while facing the same direction. The courtship will then proceed to the next stage with the couple looking their most dashing and debonair.

Reciprocal Quivering and Tilting.

In many seahorses, exchanges of quivering punctuate the next phase of courtship (Vincent, 1990). While perched side-by-side on the same hitching post, the partners adopt a characteristic posture and one of them — usually the male — begins to tremble and quaver. Holding its body stiffly erect with its pectoral fins fully extended, anchored firmly in place by its tail, the quivering begins with the fluttering of the dorsal fin and continues as a shudder that passes down its torso and quickly becomes a rapid sideways vibration of its entire body (Vincent, 1990). After a few moments the male will come to an abrupt halt and the quivering will stop as suddenly as began, only to be resumed by his partner a few seconds later. When the female’s trembling grinds to a halt, the male takes the cue and begins a new round of quivering, picking up where she left off. Back and forth, the seahorses take turns trembling and shuddering, and repeated bouts of these amazing gyrations may be exchanged for several minutes at a time (Vincent, 1990). The couple may entwine their tails during these displays of shimmying.

It’s interesting to note that both the tempo and vigor of the quivering are directly dependent on the size of the seahorses. The sideways shimmy becomes a rapid, high frequency vibration in small species like the dwarf seahorse (Hippocampus zosterae), whereas the movement is much slower in large seahorses like Hippocampus erectus, the lined seahorse. This big, buxom species sways back and forth in a stately, dignified manner. Rather than quivering, males of the larger species often merely “Tilt” towards their partners, a gesture which is akin to a polite, prolonged bow. Reciprocal quivering is an early phase of courtship that is quickly replaced by dancelike displays, but Tilting may still occur right through the final stages of courtship.

Tilting often serves as the warm up or precursor to quivering. Tilting typically begins with the male bowing toward the female and then righting himself again. These repetitive bows increase in frequency, transforming Tilting into full-blown displays of Reciprocal Quivering. The greater seahorses rarely progress past the preliminary Tilting phase, which is the more common of these two complementary performances.

Quivering is the least common of the seahorses’ courtship displays. It is seen much more often — or perhaps is just far more obvious — in dwarf seahorses and the smaller species. The larger breeds often skip over this step and get right down to dirty dancing as the male attempts to herd the female and she circles shyly away from him. Or they may simply Tilt or substitute a little slow motion, simultaneous, side-by-side swaying in place of reciprocal quivering, before busting out the real dance moves.

This delightful display is known as reciprocal quivering for obvious reasons. The male in particular appears to be energized — perhaps “stimulated” is a better description — by this activity. Encouraged by his partner’s enthusiastic response, he will eventually begin to rotate his body toward the female as he quivers. She will move away from him at first, maintaining her space, before returning his quiver (Vincent, 1990). He will then follow after her, attempting to close the distance between them while maintaining his grip on their common holdfast (Vincent, 1990). Quivering soon subsides altogether as she continues to move coyly away and they begin to circle around their hitching post in unison. The next phase of courtship has now begun.

Dancing (Carousel or Maypole).

These are the traditional dancelike displays most people associate with seahorses. They are seen in some form in the majority of seahorse species and dancing dominates the early phases of courtship in the greater seahorses (Vincent, 1990), which do much more of this wondrous underwater waltzing than the dwarf breeds.

Seahorses dance side by side and maintain a typical posture throughout these formal displays. They hold their bodies fully erect with perfect posture, tuck their heads, and conduct themselves with great dignity as they proceed, like ballroom dancers arrayed in tuxedos and formal gowns. The result is a graceful undersea ballet in which the partners grasp a common holdfast with their tails and slowly circle around it in full courtship regalia with all the elegance they can muster (Vincent, 1990). The pair stays in perfect unison as they perform this circling dance in all their finery. Their rigid posture and bright colors irresistibly remind anyone who witnesses this display of the pairs of painted ponies and stately steeds that circle ceaselessly around a merry-go-round at the amusement park. Small wonder then that the researchers who first observed this behavior dubbed it “the Carousel dance.”

Sometimes a pair begins carouseling atop a tall hitching post and spiral slowly downward until they reach the bottom again (Vincent, 1990). This lovely variation of the Carousel dance is known as the Maypole dance for obvious reasons. Together these dances play an integral role in pair formation and daily greetings for most tropical seahorses (Vincent, 1990).

Parallel Promenade.

Periodically the prospective partners will interrupt their passionate pas-de-deus long enough to move from one holdfast to another. They do not discontinue their courtship displays when they are on the move, as you might expect. Rather they simply switch from carouseling to a different type of dancing that’s better suited for covering ground. This is a type of highly stylized, side-by-side synchronized swimming known as the Parallel Promenade.

When promenading this way, the graceful movement of the seahorses is best described as prancing. The courting couple maintains precisely the same posture and carry themselves exactly the same way as four-legged horses do when prancing. That is, their bodies are erect with their heads held high, but inclined downwards, so as to keep their chins, errr — their snouts tucked tightly against their necks (Vincent, 1990). The pair swims side by side, facing the same direction, in tight parallel formation as they move from one hitching post to the next (Vincent, 1990). They travel in tandem as if harnessed together as a team. Their tails are often intertwined when they promenade, looking for all the world like a young couple shyly holding hands as they stroll the boardwalk.

Just occasionally, the male Tilts toward the female as they promenade, as if drawn irresistibly toward his partner (Vincent, 1990). If carried far enough, the tilt may become a tremor and then a sideways trembling, and if the female actively cooperates, an impromptu round of reciprocal quivering may result, particularly in miniature species. Eventually the overexcited male will regain his composure, and the promenade will proceed to its intended destination, where more Carousel dancing will ensue.

Like the other dances, promenading is an early stage of courtship seen primarily in large tropical seahorses (Vincent, 1990).

Pumping and Ballooning.

Pumping and Ballooning are pouch display 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.

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.

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.

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

Pointing.

Pointing is the prelude to mating and the transfer of the eggs. The female’s eggs will have been fully hydrated by this time, as indicated by the rounded appearance of her obviously swollen abdomen and the protrusion of her oviduct or genital papilla (Vincent, 1990). At this point, she will be anxious, even desperate, to mate. In order to ensure fertilization, the female must add water to her mature oocytes (egg cells) just prior to mating (Vincent, 1990). A ripe female is committed to mating once she has hydrated her clutch of eggs. She cannot retain the hydrated eggs indefinitely (Vincent, 1990). They can only be retained for approximately 24 hours, before they must be released. She must transfer these eggs to a receptive male within 24 hours of hydration, or lose the entire clutch. Should she be unable to transfer them to a receptive male within that time, she risks becoming egg bound, and her only recourse is to release them into the water column, spilling her eggs onto the substrate. This is an expensive waste of precious bodily resources that must be avoided at all costs. In fact, the whole purpose of the elaborate courtship ritual developed by Hippocampus is to assure that a receptive male is standing by at the crucial moment, ready, willing and eager to accept the eggs.

The ripe female signals her urgency by "Pointing" — rising on the tip of her fully extended tail and stretching vertically towards the surface of the water while raising her upturned head until her snout points straight up (Vincent, 1990). It looks almost as if the female is answering the male’s overtures by nodding her head in assent.

Pointing is an unmistakable sign that the female is ready to rise for the nuptial embrace, which will soon take place in midwater (Vincent, 1990). Pointing thus triggers an immediate response from the male, who typically reacts by Pumping or Tilting (Vincent, 1990). At first there is a stimulus-response relationship between the pointing of the female and the pumping of the male, with one eliciting the other. This helps to coordinate the couple’s courtship, assuring that both partners are fully aroused and physiologically prepared for the transfer of eggs when the moment arrives. There is a direct correlation between the frequency of pointing and pumping and the arousal level of the female and male, and one can easily judge how soon mating will occur by noting the tempo and vigor with which they perform these maneuvers. When mating is imminent, the male often responds not by pumping, but by echoing the female’s Point with one of his own (Vincent, 1990).

If he does not take the hint fast enough, the female will push off the bottom in mid-Point and rise up alone, enticing the male to follow. After a few of these solo rises, the male will eventually get the idea, and prepare to follow her lead. The couple will then rise together for the culmination of their courtship.

Copulatory Rise.

This is the final phase of courtship. It is the climax of the entire affair during which the partners meet in midwater for the transfer of the eggs (Vincent, 1990). The female initiates the rise by pushing up from the bottom in mid-Point and the male immediately follows her lead. They ascend through the water column facing each other, with their heads raised high and their abdomens thrust forward (Vincent, 1990). At this point, the female’s genital papillae or oviduct will be everted and protrude slightly from her vent, and the male’s brood pouch is usually fully inflated (Vincent, 1990). As they ascend, the female often continues to Point and the male may continue to Pump (Vincent, 1990). They will meet at the apex of their rise for the nuptial embrace.

The actual transfer of eggs takes place while the couple is suspended in midwater or slowly descending toward the bottom — a maneuver that is every bit as tricky as it sounds. Coitus is marked by an extremely awkward, fleeting embrace, aptly described as little more than a brief belly-to-belly bumping (Vincent, 1990).

As you can imagine, many difficult and delicate maneuvers are required to bring the pair into proper position for this most improbable merging. The female will attempt to insert her oviduct into the gaping aperture of the male’s inflated brood pouch. An inexperienced pair will often end up misaligned, perhaps at right angles to one another or with one of the partners too high or too low to join. This is very typical of the many false starts and abortive attempts that are ordinarily involved. The frustrated couple will separate to rest on the bottom prior to successive attempts. They may require many such rises before the proper positioning is achieved and the crucial connection is finally made.

The female will eventually succeed, with the full and active cooperation of her mate. He positions himself slightly below his mate, with the aperture of his pouch fully dilated and gaping open, ready to receive her eggs. The female will hover directly over the aperture until she can actually insert her oviduct into the opening at the top of his brood pouch or drop her eggs into the basket while hovering directly above the pouch. Pairs occasionally entwine tails when joined, but more often than not their tails will be stretched back behind them, out of the way.

If she makes a good connection, she will extrude her eggs in one long, sticky string, and the pair will hang together in midwater while the transfer is completed, drifting slowly downward as the eggs surge downward deep inside the pouch (Vincent, 1990). The entire clutch — up to 1600 eggs — is transferred in one brief embrace lasting a mere 5-10 seconds (Vincent, 1990). Sperm stream from the male’s urogenital pore into the pouch opening as the eggs are deposited (Vincent, 1990). The couple separates as they descend, drifting slowly toward the substrate. Exhausted by their efforts, the pair seek out comfortable hitching posts for a well-deserved rest. One almost expects to see them light up cigarettes at this point.

The pregnancy-sustaining changes in the male’s pouch begin the moment the last egg is tucked safely away inside this protective pocket. The male’s pouch deflates, compressing the eggs against the pouch lining in order to facilitate implantation. The male then perches and attempts to settle the eggs properly in his pouch, often undergoing a series of agitated contortions, swaying, twitching, or wagging his tail from side to side, and perhaps stretching as though trying to rearrange the eggs more comfortably (Vincent, 1990). He is dispersing the eggs uniformly throughout his pouch, giving each one the best chance to be fertilized and implant in the septum or wall of the marsupium.

Meanwhile, the female’s belly slims down noticeably as she transfers her eggs. She may lose up to 30% of her body weight after depositing a large clutch of eggs (Vincent, 1990). As a result, her abdominal plates or belly rings will be concave or pinched in for the next couple of days.

This charming courtship ritual and delightful displays are a wonder to behold. The grace and beauty of the courtship dance, with its carousel-like ballet and elegant parallel promenade, the rhythmical swaying and passionate performances of "Pointing" and "Pumping," and the fabulous midwater finale all combine to create an unforgettable spectacle that’s unprecedented in all of nature.

Okay, Jake, that’s the quick rundown on the types of ritual behavior and courtship displays that most seahorses exhibit during pair formation.

It’s good to hear that you have your pH back up into the acceptable range. Be very careful when making any additional adjustments — it’s important not to adjust the pH by more than 0.2 daily, and the more gradually it is adjusted, the better.

Just be patient when you are adjusting the pH and don’t add too much of a product designed to raise the pH too soon. Very often your pH won’t budge at all the first several times that you add such a product according to directions. That’s perfectly normal, so don’t be discouraged if your pH stays at 7.8 in initially even though you’ve added several doses of the product you obtained to raise the pH. Don’t be tempted to add more of it or to add it more often than specified in the instructions. The product must first overcome the natural buffering ability of the saltwater in your aquarium before I can change the pH level significantly. It’s like performing a titration — typically, you add several doses and your pH doesn’t budge at all, but then the very next dose you add may change the pH dramatically. Since you never know when that critical point will be reached, remain patient and continue to carefully add more of the product as directed until the pH does start to change, and then adjust it to the desired level as gradually as possible.

Best of luck with your Asian emperor seahorses (Hippocampus erectus), Jake! Here’s hoping that they continue to thrive and want to produce many broods of healthy young for you.

Happy Trails & Happy Holidays!
Pete Giwojna


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