There is an animal in St. Joseph Bay that holds a Guinness World Record. It’s a fish.

By Tom Baird

There is an animal in St. Joseph Bay that holds a Guinness World Record. It’s a fish.

When most people think of a fish, what pops into their heads is something like a bass or a tuna or a goldfish or maybe a mullet. Usually one imagines a sort of tubular, streamlined animal with fins that moves seemingly without effort through the water. But fish come in many forms and with a myriad of adaptations. Sea Robins “walk” along the bottom on their pectoral fins and flounders are flattened with the eyes on one side of the body as adults. Both are adaptations to life on the bottom. There are fish with poisonous spines and fish with lures on their heads. Yet, one of the most extremely adapted fish types are the seahorses for they hardly fit our image of a fish at all.

Seahorses are bony fish belonging to the Super Class Osteichthyes, as do most fishes. Seahorses are also ray-finned fish having webbing between the spines of their fins, however they are not strong swimmers and are found in relatively calm and sheltered waters like grass flats, estuaries, and bays. As a group, they are also restricted in their distribution to tropical and temperate seas. If seahorses prefer seagrass beds in semi-tropical shallow bays, then it is no surprise that we have them in St. Joseph Bay.

According to researchers, there are two species of seahorses found in St. Joseph Bay. They are the Lined Seahorse, Hippocampus erectus, and the Dwarf Seahorse, Hippocampus zosterae. Like their relatives the pipefish, both are well camouflaged in seagrasses. Like all seahorses, both species swim by undulations of their dorsal fins (the fin on the top of most fish) and use their pectoral fins to steer. Seahorses lack a caudal or tail fin. Instead the body tapers to a prehensile tail like a monkey. They use these tails to cling to the blades of turtle grass or to algae or soft corals. There they lie in wait and take in any small morsels of plankton or organic material that drift by on the current.

Overall, seahorses do not attain a large size. One species grows to a little over a foot (the big-belly seahorse or pot-bellied seahorse, Hippocampus abdominalis), but most are smaller at about a half inch to a few inches in length. There are even pygmy seahorse species that grow to no more than a half an inch and have only started to be described in the past fifteen years. Our Dwarf Seahorse only grows to a length of an inch maximum. Our other common seahorse species, the Lined Seahorse, can grow up to nearly six inches, but is rarely found that large in the bay.

Besides their shape and being well camouflaged, the most unusual aspect of seahorses is that the males get pregnant. Well, sort of. After an elaborate courtship display, that includes swimming with their tails intertwined, like holding hands, a male and female seahorse will release from the sea grass and drift upward and face each other. Belly to belly, the female will transfer her eggs to a brood pouch on the male’s abdomen. The eggs become embedded in the tissues inside the brood pouch and the male even supplies them with hormones. The fertilized eggs then grow and develop into baby seahorses inside the brood pouch of the male. The female even comes to visit the male daily during this period. After two to four weeks, the eggs have developed into tiny seahorses. The male will then arch his back and forcibly expel them into the water column. Depending on the species and environmental conditions, on average a 100 to a 1000 little seahorses are produced with each pregnancy. Protecting the developing young inside a parent’s body obviously has survival advantages.

The tiny seahorses immediately begin to feed and grow, yet their chances for long term survival are slim. Being weak swimmers, the can easily be carried away by currents to unfavorable habitats. Seahorses in general are far from immune to predation. Everything from sea turtles to larger fish, sea birds, crabs and humans consume seahorses. Prepared seahorses can be purchased on wooden skewers at Chinese street stalls. A great many seahorses are harvested for components in traditional Chinese remedies. Besides being taken for food by other sea creatures and humans, sea horses are also collected for the aquarium trade. Under the right conditions and with appropriate food, our little Dwarf Seahorse and Lined Seahorse do well in marine aquaria.

Despite these threats, the biggest threat to seahorse populations comes from habitat destruction and pollution. Seahorse populations have declined in U.S. waters over the last ten years, and worldwide there is little data on the size of seahorse populations. The protection of the sea grass beds in St. Joseph Bay is critical to sustaining the seahorse populations there. 

You can easily find seahorses in the bay by gently lifting out a large clump of drift algae and placing it in a bucket or plastic tub. Myriad creatures will come out including the occasional seahorse. They are also collected in seine nets and can be seen by careful observation of the grass blades while snorkeling. After observing, please gently and carefully return the little seahorses back into the bay. These are highly adapted and specialized fish and it would be a shame for them to disappear in our waters.

So which fish found in St. Joseph Bay is a Guinness Record holder? The Dwarf Seahorse holds the record as the slowest swimming fish in the world. Makes you kind of proud doesn’t it?

Tom Baird has been a fisheries biologist, high school and community college teacher (oceanography and microbiology), director of a science and environmental center, teacher of science and principal in Pinellas County as well as an educational consultant. He retired from the Florida Department of Education and he and his wife divide their time between Tallahassee and Cape San Blas.