The Oriental Polybranchia (Polybranchia orientalis) is a tropical species belonging to the family Polybranchidae. This species is known to occur throughout the Indo-Western Pacific region and has been found in Africa, Japan, Hawaii, New Caledonia and in Australia. This species was previously known as Phyllobranchus or Phyllobranchillus orientalis. This species is rather common but is seldom seen due to its algae like appearance that helps it blend in with its surroundings. If this species is disturbed by predators or divers it has the ability to shed its cerata as a defense mechanism. This defense mechanism is known as ‘Autotomy’ and the cerata grow back quickly in just a few days.
This species looks very similar to Polybranchia pallens and Cyerce elegans. This species has a hump in the middle of its back and stalked leaf like cerate on the right-hand side of its body. Members of the Polybranchia genus have fine branching digestive ducts in their leaf like cerata whilst the digestive gland in species reaches only into the basal ceratal stalk.
The Oriental Polybranchia (Polybranchia orientalis) grows to a maximum length of approximately 6cm.