The common seadragon or weedy seadragon (Phyllopteryx taeniolatus) is a marine fish related to the seahorses. Adult common seadragons are a reddish colour, with yellow and purple markings; they have small leaf-like appendages that resemble kelp fronds providing camouflage and a number of short spines for protection. Males have narrower bodies and are darker than females. Seadragons have a long dorsal fin along the back and small pectoral fins on either side of the neck, which provide balance. Common seadragons can reach 45 cm (18 in) in length.