I'm not sure if you are asking for an actual family name (which I would have to look up - Hippocampidae??) or whether you are just asking in general terms where seahorses fit into the animal kingdom. You'd be surprised how many people don't know that. In fact, some people think that seahorses are invertebrates. Actually, seahorses are bony fishes, right up there with bass, cod and flounders. Their closest relatives are the pipefishes, which are also very interesting to observe. I have seen seahorses on the south shore of Cape Cod on two occasions, both times in association with floating mats of Sargassum weed which had drifted north from the Caribbean in the Gulf Stream, then blown into shallow water. We get quite a few tropical visitors showing up on the south shore of Cape Cod during the summer months, from that same source. Portuguese man of war are one such non-native species that sometimes appears. Pipefishes are quite common here in summer, but seahorses are only occasional visitors. Regards, Paul M.