Seahorse Serenade: The Dance of Underwater Love
Printed in Hobe Sound Magazine, March 2024
By Jill Griffin, Ph.D., Executive Director, Hobe Sound Nature Center
(in cooperation with the Nathaniel P. Reed Hobe Sound National Wildlife Refuge)
Picture a creature so mythical, it seems to have emerged from an underwater fairy tale, drifting elegantly through the ocean, and you’ve just conjured up a seahorse. These tiny marine wonders have captured the human imagination for centuries, symbolizing good luck, persistence, and peace. From their monkey-like prehensile tails, to their horse-like heads and chameleon-like eyes, seahorses are the ocean’s perfect Frankenstein creation. Given their awkward swimming skills and unusual, upright posture, they spend most of their time anchored to seagrass blades and algae by their tails, suspended in time and perfectly blended into their surroundings. Seahorses exhibit stealth ambush hunting skills that would make a great white shark jealous, bear specialized body armor that has mystified physicists for decades, and oh, one more thing – the males have assumed the burdens of pregnancy!
Though some male fishes provide considerable care to their young in the form of egg incubation, aeration, and protection, seahorses are the “Super Dads” of the sea. In fact, seahorses and their close relatives, the sea dragons, are the only male animals on the planet that get pregnant and give birth to their young. The brood pouch on their belly acts much like a womb, providing oxygen and nutrients to the developing embryos, as well as regulating temperature and salinity. When fully developed, the males eject anywhere from 3 to over 1000 “small fries” into the water column, at which point they are on their own.
The love story that leads up to the birth is equally as fascinating! Seahorses are monogamous, and, in preparation to mate, they engage in a dramatic and enchanting underwater dance that persists for several days. It often begins with the male and female holding each other’s tails and eventually evolves into a fascinating waltz, in which they mirror each other’s movements, twirling and gliding in harmony for hours. Yet, the beauty of this dance goes beyond its elegance. Its purpose is to strengthen the pair’s bond and synchronize their reproductive cycles. When the moment of glory arrives, the female merges bellies with the male and deposits her eggs into his brood pouch. Though her reproductive duties are now officially complete, the bond they created while dancing motivates the female to conduct daily visits with her mate to check in and say hello. Yet, why, over evolutionary time, have male seahorses assumed this energetically costly yet critical role? The first theory is that, by fertilizing and carrying their brood inside a pouch, the males ensure they are the sole father of each developing embryo, eliminating any chance that another male’s sperm can fertilize his lady’s eggs. The second theory rests on the fact that less than 0.5% of the small fries survive to adulthood. Scientists speculate that this necessitated the release of females from the burden of carrying their young, allowing them, instead, to start developing new eggs immediately, effectively speeding up the reproductive cycle to ensure species survival.
The Sunshine State is home to three species of seahorses. Given their preference for dense seagrass habitats, they are important sentinels of ecosystem health. Seagrass ecosystems in Florida have experienced widespread, dramatic declines since the late 1980s, resulting in shrinking seahorse populations, exacerbated by the overharvesting of seahorses for the aquarium trade. However, not all hope is lost, thanks to efforts to improve water quality, revive seagrass beds, and restore estuary ecosystems. In fact, last summer, 6-year-old camper Mia and I carefully glided our dip nets along the seagrass floor of the Indian River Lagoon and both squealed with delight when we noticed a tiny seahorse tucked into the bottom of my net. I told her that these magical creatures have much to teach us about the fragility of aquatic life, and by saving seahorses, we preserve a little bit of magic in our oceans. So, we ceremoniously held hands, closed our eyes, and wished our lilliputian creature good luck as we gently returned her to the warm waters from which she emerged.