Hippocampus

Forward of the ribs it is a horse, with short hair on head, forelegs and chest and a mane of long, supple fins; its forehooves are webbed fins that fold on the forward stroke and spread on the pull. Behind the rib cage it becomes a fish, tapering 14 feet to a broad, horizontal tail fin, with a dorsal fin on the rump. Its hues are those of seawater, from ivory and aqua through the pale and deep shades of green and blue.

Peaceful by nature, hippocampi fight only when cornered or to protect one of their own or an ally, and usually outswim any threat. They bite by snapping the head out, crunching down and letting go at once, never holding on, and they ram with their heads hard enough to stun or break bones. Dense muscle protects them, and their blood clots fast in water, limiting both weakness and the lure to sharks, which have just a 20% chance of frenzy when a hippocampus is the only one bleeding.

They roam deep water anywhere, in oceans or freshwater lakes, breathing fresh or salt water with ease. They can breathe air but must gulp water often to avoid drying out, and they cannot leave the water. In size, life span and temperament they resemble horses, though far brighter. Wild herds number 2d4: one stallion with 1d4 mares, the rest youngsters of both sexes. A mare lays a single large egg that hatches in six months (twins 1%), and foals grow fast, matching adults within a year and mature within two. Their legends speak of a Great Herd, thousands strong or at least hundreds, wandering the uncharted far seas, which no outsider has ever seen. They graze on seaweed and soft plants, crunching shellfish and coral when they must.

Water-breathing peoples, especially tritons, seem to tame them, but really the two are partners: the hippocampi serve as mounts and allies in exchange for protection. They keep ties with mermen, sea elves and seafaring surface folk as steeds, guides and friends. Shrewd judges of character, they refuse to help evil beings or anyone hostile, yet they aid surface visitors and have rescued countless shipwrecked sailors, though young ones may forget that landfolk need air. They want no treasure and scorn collars, leg bands and similar trinkets, but love foods they cannot find underwater. Eggs bring 1,500 gp and young 2,500 gp, yet anyone a hippocampus once saved may assault a merchant selling them at market and try to free them.