This week’s What’s on the van? comes from Malgosia Nowak-Kemp, Collections Manager in the Museum’s Zoological Collections.
Although called a “seahorse”, it is of course a fish and its name Hippocampus comes from the Greek “hippo” meaning a horse and “kampus” meaning a “sea monster”. But it certainly does not look like a monster. Seahorses live in tropical or temperate seas where the water is shallow, with plenty of plants, reefs or mangroves. Different species are of different sizes, ranging from tiny ones measuring less than 2 cm to much bigger ones reaching about 36 cm. They are quite unlike any other fish as they swim upright with the head high up and the tail below and not like other fishes that swim in a horizontal position.
Their body also lacks the typical covering of a fish –the fish scales, but has special plates that are arranged in rings and covered by skin. The number of rings is most helpful in the identification of the 50 or so species of Hippocampus.
The seahorses are famous for the male carrying the fertilised eggs in a special body pocket, or pouch. Laying and fertilising the eggs is preceded by a courtship where the male and female swim together and engage in a courtship dance, after which the male becomes responsible for the care and protection of their brood. When the young are ready, a process similar to giving birth takes place. The male contracts the muscles and thus expels the young fish into the water. Although most of the seahorses release a large number of young, less than 1% survive and the urgent need for protection of most species is now recognised by marine conservation bodies.