Short Snouted Seahorse (Hippocampus hippocampus) and the Long Snouted Seahorse (Hippocampus guttulatus)
There are two species of seahorse in UK waters: the short snouted (above left) and the long snouted (above right). They can both grow to a maximum length (or height) of around 15cm and live in shallow, inshore waters amongst seaweeds and seagrass which they cling to with their tails. The main difference between the two species is, unsurprisingly, the snout, although the long snouted seahorse can be further distinguished by the presence of longer spines on the back, just above the dorsal fin. Both species of seahorse can change colour to a limited extent to match their surroundings. Seahorses feed mainly on very small marine crustaceans.
Being mostly a tropical and sub-tropical species neither seahorse species has a wide distribution around the UK. The short snouted sea horse is only found around the English Channel, off the south west coast of England and parts of the southern Irish coast, whereas the long snouted has a wider distribution being found in all of these areas, as well as in parts of Wales and northern Scotland. Seahorses are often taken by predatory fish and have to rely on camouflage to avoid detection as they are poor swimmers, with only their small dorsal fin undulating to provide them with weak forward propulsion. Seahorses have an unusual breeding pattern. Males will fight each other for a mate and once other suitors have been fought off a male and female may breed together for several breeding seasons. The female passes eggs on to the male who then fertilises them within his own body. The eggs grow and hatch within the male who then gives birth to live young when the eggs hatch inside him.
The IUCN (International Union for the Conservation of Nature) does not have enough data on seahorse numbers to make an accurate assessment of their numbers and classes them as Data Deficient. However, there was some good news about seahorse numbers in 2007, when a breeding population of seahorses was found in the River Thames around Southend-on-Sea. This population is still thought to be present and breeding today. However, in much of their UK habitat they are threatened by commercial trawling and recreational use of the sea (such as as the anchors of pleasure vessels tearing up the seabed). For this reason there is much concern over the long term stability of UK seahorse populations.