An educational resource dedicated mainly to the photography
and diversity of marine life that can be found in coastal waters
and intertidal areas of Great Britain and Ireland by David Fenwick.

A-P-H-O-T-O Wildlife Stock Image Library
Polycera quadrilineata (O.F. Müller, 1776) feeding behaviour on Wakame, Undaria pinnatifida.
Polycera quadrilineata
looking for Membranipora
- on Undaria pinnatifida 1

Polycera quadrilineata
looking for Membranipora
- on Undaria pinnatifida 2

Polycera quadrilineata
shot holed Wakame
- Electra zooids left alone 1

Polycera quadrilineata
shot holed Wakame
- Electra zooids left alone 2

Polycera quadrilineata
feeding on Wakame
- shot holed algae 1

Bryozoan / Sea mat
Membranipora membranacea
- round juvenile colony 1

On weed washing algae to look for nudibranchs at Newlyn Marina, 21.05.17, a large number of Wakame, Undaria pinnatifida, plants were found that had been extensively shot holed. A frond and pieces of fronds were taken away for examination.

On examining the material, the material was found to have two species of bryozoans, sea mats, growing on it, Electra pilosa and Membranipora membranacea, the latter being the food of the sea slug Polycera quadrilineata, which was found in the samples that were examined.

Small round juvenile Membranipora membranacea colonies were observed on the Wakame, as were the more starry shaped colonies of Electra pilosa. The only evidence of feeding was that zooids of Electra pilosa had been left exposed and had not been devoured. This suggests only Membranipora membranacea was being targeted and eaten, and by Polycera quadrilineata past and present.

What is unusual is that on the brown algae Laminaria, Polycera quadrilineata grazes the dorsal surface of the zooids of Membranipora membranacea. On Wakame, Polycera quadrilineata has learned to feed on the ventral surface of Membranipora membranacea by clearing the algae, which leads to the shot holing once the bryozoan has been devoured.

Wakame, Undaria pinnatifida, is a serious non-native invasive species that was relatively recently appeared. The feeding behaviour of Polycera quadrilineata is either new or adapted. Polycera quadrilineata may also use light to detect colonies of bryozoa on the underside of Wakame fronds.

Polycera quadrilineata feeding behaviour Membranipora membranacea Wakame Undaria pinnatifida Sea Slug Nudibranch Images
The main objective of this website is in furthering environmental awareness and education through the medium of photography. To increase awareness and access to the wildlife of the region and help
people find and identify it. Sometimes the difference between species is obvious but many species can only be determined by observing microscopic characteristics that are specific to any one species.