It’s interesting that some of your youngsters are beginning to develop cirri. Although they are a highly variable trait, Hippocampus erectus (i.e., Mustangs and Sunburst) is one of the species in which these extravagant appendages are not uncommon. Those hair-like growths on the head and neck of some of the youngsters are known as dermal cirri, and are an attractive adornment possessed by certain seahorses. Dermal cirri are fleshy tabs or branching outgrowths of the skin that serve to break up the seahorse’s outline and allow it blend into its weedy habitat all the better, a sort of natural camouflage. Unlike spines, cirri are not permanent structures in most cases. Up to a certain age at least, seahorses appear to be capable of growing or shedding these fleshy filaments as the occasion demands in order to better suit their surroundings. For example, specimens that are rafting in clumps of Sargassum are apt to have well-developed cirri, giving them an appropriately shaggy appearance, while a seahorse inhabiting the mudflats of an estuary will be smooth skinned. Cirri grow most commonly on the head and neck region and are more common in juveniles than adults.
It’s a shame seahorses with well-developed cirri like some of your juvies aren’t more commonplace because they can be quite breathtaking. A heavy growth of cirri can transform an ordinary specimen into a real show horse, making them appear as if they were adorned with a fancy mane or wearing an Indian war bonnet. A seahorse with extravagant, well-developed cirri can indeed be very exotic looking, but sometimes it has the opposite effect, lending them a comical appearance instead. I’ve seen shaggy specimens that looked like they were having a bad hair day, sporting a Mohawk or spike hairdo. Voila — a punk-rock pony, going through its rebellious teenage phase! Either way, they dress up the seahorses and give them a little extra pizzazz, and that’s what makes seahorse keeping so much fun!
By all means, please do keep us updated from time to time on the progress of your juveniles as they grow and mature, Tammy! Here’s hoping that the move into more spacious grow-out tanks goes smoothly and all of the youngsters tolerate the transfer very well.