Hi Suman, i am a marine biology student, barnacles are suspension feeders meaning they feed on planktons and detritus(as long as it suspends in the water column), so basically they help i

Suman:

For fossil Barnacles you may start by looking at this link:

http://www.sciencedirect.com/science/article/pii/S0016787814000066

Best

Syed

Controls the plankton standing stock

Just checked to see that my answer is cut. Here's the cont. "Basically they help in cleaning the water by acting as natural filters of the sea, just like oysters do. And just like Andr3

Hi colleage. I think that the most clear and important works about the ecological role of barnacles are the published by J. Connell.

First, you can read: Joseph H. Connell. The influence of interspecific competition and other factors on the distribution of the barnacle Chthamalus stellatus (PDF). Ecology 42(4) (Oct. 1961), 710-723. and furthers.

As you contemplate the "role" the barnacles play, keep in mind that balanid colonies from an important substratum for other organisms.  The irregular surface, with an array of nooks and crannies, forms important habitat for polychaetes, turbellaria, small crustaceans, etc. while the exposed surfaces (especially the empty plates of deceased barnacles) offers habitat for epibionts.  The entirety is an important community that in turn supports predator and prey.  You'll want to check the classic work of Paine and of Connell from the 1960s. 

In trophic level, it is suspension feeder

Hi. Also, keep in mind that barnacle larvae are often extremely abundant in mesozooplankton samples (even more than copepods, at times). During the naupliar phase they can be very voracious preying on different kinds of organisms, so they may have a significant trophic role during naupliar planktonic stages as well.

Thank you so much all of you!!! I do appreciate all the answers.

Dear Suman,

Barnacles are zooplankton as larvae and they are benthic as adults so they serve a role in two different communities in their life time.  As zooplankton they eat Phytoplankton in the water column and they are good for other animals that are in the water column.   When they leave the nauplius stage mentioned above and metamorphose to the cyprid larval stage they are food only as they no longer eat but search for a.place to settle.  After they settle and metamorphose into juveniles and grow into adults they are still filter feeders as they were as nauplius larvae but now they are members of the benthic community where they still consume Phytoplankton but not at the surface until the tide is low and they are food for animals.that go to the bottom or live on the bottom all of the time.  As the tide goes out the water is not as deep and the surface and botom communities meet.  Thanks.

In addition to the contribution of Robert S. Prezant I would like to add that substrate modification by barnacles is especially important in early phases of succession. In the North Sea, new and empty hard substrates may become completely covered by barnacles after an immersion of only a few weeks.