A seahorse is any of 46 species of tiny marine fish in the genus Hippocampus. Having a neck and head similar to a horse, seahorses also feature an upright posture, segmented bony armor, and a curled prehensile tail.
Seahorses are chiefly found in shallow temperate and tropical saltwater worldwide, from about 45°S to 45°N. They exist in sheltered areas such as estuaries, seagrass beds, mangroves, and coral reefs. Four species are located in Pacific waters from North to South America. In the Atlantic, Seahorses range from Uruguay to Nova Scotia. Colonies of Seahorses have also been observed in European waters such as the clean Thames Estuary.
Seahorses range in size from 5⁄8 to 14 in (1.5 to 35.5 cm). They are named (as mentioned above) for their equine features, with long-snouted heads and bent necks and a distinctive tail and trunk. Although they are relatively bony fish, they do not have any scales; but instead, thin skin extended over a series of bony plates organized in rings throughout their bodies. Each species has a specific number of rings. The covering of bony plates also guards them against predators, and because of this outer skeleton, they don’t have ribs. Seahorses tend to swim upright, thrusting themselves using the adorable dorsal fin, another feature not shared by their close pipefish relatives, which tend to swim horizontally. Razorfish are the only other known fish that can swim vertically. The pectoral fins, situated on either side of the head right behind their eyes, are utilized for steering. They lack the caudal fin characteristic of fishes. Their prehensile tail is formed of square-like rings that they can unlock only in the most intense conditions. They are adept at camouflage and can reabsorb and grow spiny appendages depending on their environment.
Evolution and the fossil record
The known anatomical evidence, supported by biological, molecular, and genetic data, confirms that seahorses are highly mutated (naturally) pipefish. The seahorses’ fossil record, however, is very sparse. The best-studied and best-known fossils are specimens of Hippocampus guttulatus, from the Marecchia River Formation of Rimini Region, Italy, recording back to the Lower Pliocene, about 3-3.5 million years ago. The oldest known seahorse fossils are of two pipefish-like species, H. slovenicus and H. sarmaticus, from the coprolitic range of Tunjice Hills, a middle Miocene lagerstätte in Slovenia recording back about 13 million years.
Modern Molecular dating finds that seahorses and pipefish diverged during the Late Oligocene. This has led to the consideration that seahorses evolved in response to a large region of shallow water, newly created resulting from tectonic events.
The male seahorse is outfitted with a ventral pouch. When mating, the female seahorse puts up to 1,200-1,500 eggs in the male’s pouch. The male takes the eggs for 12 to 48 days until the seahorses appear thoroughly developed but rather small. The young are then carefully released into the water, and the male often mates again within days or even hours during the breeding season.
Seahorses use their adorable long snouts to consume their food. However, they are relatively slow to consume their food and have elementary digestive systems that lack a stomach, so they must constantly eat to stay alive. Seahorses are not really good swimmers, and for this reason, they need to anchor themselves to coral, seaweed, or anything else that will land the seahorse in place. They do this by using their delicate prehensile tails to pick their object of choice. Seahorses feed on simple small crustaceans floating in the water or randomly crawling on the bottom. With excellent camouflage, seahorses ambush small prey that flows within striking range, waiting and sitting until an optimal moment. Mysid shrimp and other tiny crustaceans are known favorites, but some seahorses have been seen eating different kinds of invertebrates and larval fish.