A pregnant father who floats around. No, this is not the creation of high-fi science and technology, nature crafted this gentleman, which happens to be the seahorse. This unusual fish, which evolved around 40 million years ago has survived till the present day with ever-so-little change in the structure of its body. Resembling a fusion of numerous animals, its head looks like a horse, its prehensile tail is like that of a monkey, eyes like that of a chameleon and a body armour like that of a locust. This fish has seized the imagination of artists, writers and poets and has found its place in mythology, folklore and superstition. Its biology is just as interesting.
To impregnate a female in the animal world, the males fight with each other. So, in the seahorse world, the females get into a scuffle to win over the rights to impregnate the male, right? Wrong! It is still the males that compete for the females. To impress the females, males pull each other’s tails, drag each other around on the bottom of the seabed, snap at each other with their snouts. Have you heard of giraffes wrestling by using their long, curved necks? The seahorses do something similar but underwater!
Seahorses mate with only one partner and are thus monogamous for the entire breeding season. Before breeding, seahorses court for several days. Researchers believe that this courtship behaviour synchronises the animals’ movements and reproductive states so much so that the male can receive the eggs when the female is fit to shed them. During this period, they may change their colour, swim side-by-side holding tails or gripping the same strand of sea-grass with their tails, and wheel around simultaneously in a ‘predawn dance’, in beautiful romance. Eventually the ‘true courtship dance’ takes place, which lasts for eight hours. During this, the male pumps water through the egg pouch on the stomach, through its trunk that expands and contracts to display that it is empty and forcefully expels water. And they do all this to get pregnant for three weeks. Imagine, not being able to search for food while your female partner can happily move around and have what she desires, and at the end of this, the guys go through 72 hours of labour pain and sapping final contractions to give birth to upto 200 babies. The experience leaves the seahorse drained off colour. After all this, the male starts showing off his pouch, begging to get pregnant again!
When the females’ eggs reach maturity, she and her partner frees themselves from their anchored state and drifts upwards snout-to-snout, spiralling as they rise, as if in a dance of celebration. The female then inserts her tubular organ, called the ovipositor into the male’s brood pouch and deposits hundreds-and-thousands of eggs. The picture looks funny though — the female shrinks while the male swells up. Both animals then fall back into the seagrass bed as the female swims away. The male then releases the sperms directly into seawater, where it fertilises the eggs, nested in the pouch wall, which is then surrounded by a spongy tissue. It does not stop there. The father then supplies the eggs with a kind of hormone that mimics the properties of milk. This hormone is called prolactin. Embedded in the pouch, the eggs are provided with oxygen. The eggs then hatch in the pouch and the salinity of the water is regulated here that prepares the baby seahorses to face the sea.
The bond between the partners is quite strong. The female always comes back for ‘morning greetings’. They interact for about six minutes and relive their ritual courtship dance. This is to flirt with each other apparently to renew the romance and consolidate the relationship! If by chance, one mate dies, it takes weeks to start searching for a new partner. This is because seahorses live in secluded groups and move very little. Let us pledge to protect seagrass beds and conserve a breed of such dedicated fathers.