Asian Diver (English)
STORIES FROM THE STABLES
As enigmatic as they are charismatic; Dr Richard Smith’s research exposes the private lives of pygmy seahorses
A pair of Pontoh's pygmy seahorses in Sulawesi, Indonesia
I could never have foreseen what fascinating subjects these diminutive fish would make. Setting out to discover the private lives of pygmy seahorses, I embarked on my doctoral research, studying the biology and conservation of pygmy seahorses, based on what we already knew of the larger seahorses.
Male pregnancy had already been confirmed from dead specimens, but their natural behaviours on the coral reefs of Southeast Asia remained a mystery. Ultimately, my notes after a research dive read more like an E.L. James novel than scientific records, but I was able to uncover many of these mysterious animals’ darkest secrets.
You might not expect pygmy seahorses to have distinct personalities, like characters from a soap opera, but after almost 1,000 research dives watching every last detail of these fish’s lives, I can certain attest to their fascinating and sometimes quirky behaviours.
I have already written about the group of Denise’s pygmy seahorses, Tom, Dick, Harry and Josephine, who shared a gorgonian coral on Wakatobi Dive Resort’s House Reef. These four showed us how a life trapped together on a gorgonian can take unexpected turns. Josephine shared her amorous attentions with both Tom and Dick whilst poor Harry bided his time for his chance to carry little pygmies of his own. This little “ménage à quatre” sparked plenty of rivalry between the males, but ultimately Tom and Dick shared parental duties in the group.
You might not expect pygmy seahorses to have distinct personalities, but I can attest to their fascinating and sometimes quirky behaviours
THE “ROYAL” THREESOME
In hindsight it seems most distasteful, but my research dictated that I next turn my attentions to a female-biased ménage à trois. I had already seen that under the circumstances of a male biased sex ratio, the female (in this case, Josephine) was able to produce clutches of eggs just days apart in order to impregnate two males (Tom and Dick). Subsequently, I was intrigued to
find out whether a single male would accept eggs from two females. Luckily, at Wakatobi there is no shortage of pygmies and I soon found a perfect group: Charles, Diana and Camilla.
I spent many hours with the trio, observing and recording their every interaction. I found that Charles and Diana shared a “core area” on one side of the gorgonian. A core area is the term I gave to the area they carried out their social bonding dances, as well as where they mated and slept. They raised several broods together, but all the while Charles was also flirting with Camilla.
Each morning, after dancing with Diana, Charles would leave their core area and swim directly to the other side of gorgonian where Camilla patiently waited in her own core area. Camilla and Charles would carry out the same social bonding dances but they never mated. In the world of pygmy seahorses, it is always best to hedge one’s bets.
Unlike the pugnacious males, the two females eschewed violence and the conflict of the male-biased group wasn’t seen. Tom, Dick and Harry would regularly attempt to strangle each other with their tails, sometimes resulting in three-strong tussles. The females, on the other hand, were indifferent to each other and much more measured in their behaviours.
The tension on a male pygmy seahorse’s comically puckered face immediately prior to giving birth is unforgettable. As the only male in the animal kingdom to truly undergo this otherwise womanly miracle, I can only imagine how he feels.
The birth certainly seems to involve the expected labour pains. On the several occasions I’ve been lucky enough to witness it, numerous contractions have been needed to pop the full brood out. Charles had to crunch back and forth for several minutes to free the last of his fry, before being left with terrible stretch marks!
The newly born miniature seahorses only momentarily saw their father before being swept out to sea. They take this opportunity to float in oceanic currents for a few weeks before finding their own gorgonian on which to settle. After it is found, they need only five days to change from their dark, free-floating colouration to one that matches their new gorgonian home in every detail of both colour and surface texture.
Charles’ chores, however, were only half complete. He swam right back to the expectant Diana, and after a brief courtship dance they mated. Diana’s eggs were fertilised as they passed into his pouch, setting both their minds at rest that no adultery had taken place. The absolute certainty of his fathering all the young explains why seahorse males stand alone amongst all others in their dedication to paternal duties.
Would jealousy be a feature of a male pygmy seahorse’ s behaviour when they were happily partnered?
Broadening my search further, I found another group of pygmies on Wakatobi’s House Reef that comprised of three pairs. This offered the opportunity to investigate how bonded pairs interacted with each other. Would jealously be a feature of a male pygmy seahorse’s behaviour when they were happily partnered? Mapping their home ranges and recording their social interactions, I concluded not.
On a gorgonian as big as a 34-inch LCD screen, individuals spent their entire lives exploring an area in some cases as small as three adjoining Post-it Notes whilst the largest spanned the area of a double page spread in this Big Blue Book. Males generally used less space than females, which is probably due to the difficulty of travelling when inflated with young. When happily settled with a single partner, males appeared to pay no attention to other males, with their home ranges often strongly overlapping and without defended territories.
Denise’s pygmies are more active than you might imagine. Divers usually only stay just long enough to snap a picture, but if you spend a little time watching these tiny fish you’re more than likely to witness them swimming. In all but the strongest currents, they move about every five or six minutes. Hunting for prey to fuel their constant egg production and pregnancy is a fulltime pursuit, so they frequently move to pastures new in search of the miniscule crustaceans that live on the surface of gorgonians.
Although small in stature, pygmy seahorses have not been shortchanged in the character department. Their reputation as the stars of the reef go way beyond the aesthetic, and the more you learn about them, the more you appreciate them. Next time you see some pygmies on the reef, why not take a little time to watch the soap opera unfold before your own eyes.