There are many strange creatures inhabiting earth’s oceans. Sea Horses could be considered among the strangest fish to live in the sea. There are about 46 species of sea horses, and they belong to the genus Hippocampus, a Greek word meaning horse. Their heads and bodies superficially resemble those of horses. Genetic evidence suggests they diverged from pipe fishes between 25 million-30 million years ago. During this time period tectonic processes expanded shallow water habitat favorable for sea horses. They prefer shallow ocean where sea grass can grow. These odd fish use camouflage in sea grass beds to avoid predators and to sneak up on prey. They were probably most abundant during Pleistocene Ice Ages when sea levels dropped, creating extensive sea grass habitat. However, fossils of sea horses are known from just the Miocene and Pliocene. Genetic evidence suggests sea horses originated in the Pacific and colonized the Atlantic during 2 separate expansions.
Sea horses are an evolutionary improvement over pipe fish, though the latter are still extant. Both types of fish suck in tiny animals such as brine shrimp, copepods, and newly hatched fish fry, but the vertical position of sea horses helps them suck in prey from a greater distance than pipe fish can. 3 more traits make sea horses seem unusual. They are armored, they have prehensile tails, and the males get pregnant. During mating females transfer their eggs to the male’s pouch. The males then give birth to up to 2500 live young.
The vertical position of a sea horse allows them to suck in food from a greater distance than their cousins, the pipe fish. They have to eat constantly because their digestive systems are inefficient.
Sea horse life cycle.
Scientists who authored a new study about sea horses captured them in Tampa Bay, Florida for a year during 2022/2023. They found dwarf sea horses were most abundant during the month of October. Sea horses are vulnerable due to the loss of sea grass beds caused by dredging and pollution. They are also a frequent bycatch of shrimp trawlers. Some Chinese cooks make a medicinal soup from sea horses, but reportedly they are flavorless.
References:
Brown, P.; P. Bland, and E. Rov
“Seasonal Population and Ongoing Morphometric Analysis of Wild Dwarf Sea Horses Hippocampus zosterae“
Georgia Journal of Science 82 2024
Teske, P.; M. Cherry, and C. Matthee
“The Evolutionary History of sea horses (Syngnathidae: Hippocampus): Molecular Data Suggests a West Pacific Origin and two invasions of the Atlantic”
Molecular Phylogenetic Evolution 30 (2) 2004
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