According to present knowledge, two seahorse species are recognized in Europe. A third one, immigrated from the Red Sea, occurs in the Eastern Mediterranean. You will find below some information on these three species and how to identify them.
Long snouted seahorse
Hippocampus guttulatus
Size: 10-16 cm (max. 18 cm). From Great Britain to North Africa; all of the Mediterranean.
Photos P. Louisy and P. Francour
ID criteria:
Snout long: 3 to 4 times longer than high.
No marked ridge on top of the head, but a small coronet with 5 knobs (usually not very prominent); horizontal plate in front of coronet.
Often golden or greenish brown, sometimes blackish, light grey, golden yellow or bright pink. Usually white dots or dashes, sometimes organized in wavy lines (but also sometimes invisible or absent). Often (but not always!) skin filaments, sometimes branched, on the head and body (mostly dorsal part).
Size: 9-13 cm (max. 15 cm). From North Sea and the English Channel to West Africa; all of the Mediterranean.
Photos P. Louisy
ID criteria:
Snout short: 2 to 2,5 times longer than high.
Triangular ridge on nape neck.
Often quite uniformly brown, sometimes dark, sometimes very light, occasionally bright yellow. Sometimes with dark dots or dashes, rarely with white speckling; may have a marked marbled pattern. Usually lacking skin filaments (but their presence is not so unusual), body usually not very spiny (but...).