The ruby seadragon (Phyllopteryx dewysea) is a marine fish in the family Syngnathidae, which also includes seahorses. It inhabits the coast of Western Australia. The species was first described in 2015, making it only the third known species of seadragon, and the first to be discovered in 150 years. A specimen found on shore in 2007 was 23.5 cm (9.3 in) long. The team that discovered this species, named the marine fish after its color and they believe it is so red because it inhabits the deeper waters, where red hues are absorbed more efficiently and being red colored can help camouflage.