The nemertean worm Nemertopsis quadripunctatus is a common associate of C. mitella in Hong Kong, and is found in the mantle cavity of the barnacle.

The worm can reach 8cm in length but is only 1mm wide.

It feeds on the brooded eggs of the barnacle which are housed in the mantle cavity, and may also feed on material filtered by the barnacle.


An animal that has reproductive organs of both males and females of the species, and can act as ‘male’ or ‘female’ in the reproductive process.


First stage larvae of crustaceans.


Tiny water dwelling plants.

Lower eulittoral zone

An area of shoreline that ranges from the high water mark to areas that are permanently submerged.


Permanently attached and not free to move.