Posted by: lapazfarm | March 25, 2010

Week 20: Tunicates and the fouling community


Tunicates, despite being extremely simple looking at first appearance, are chordates just like us!  And therefore they are the animal most closely related to us thus far. Hard to believe, eh?

Well, chapter 13 in the Seaside Naturalist will fill you in! Go ahead and read that and then complete the following:

Questions to answer:

  • What is the taxonomyof a tunicate?
  • Why is it placed in this phylum along with dogs, fish, snakes, and humans (among others)?
  • What dramatic changes take place during the tunicate life cycle?
  • Where did the name “tunicate” come from?
  • What are some other names for tunicates?
  • How does the adult tunicate feed itself?
  • How does it reproduce?

And here is a site with a bit  more tunicate info if you are interested:

Make a sketch of tunicate adult anatomy in your notebook and label it.

Look back in your notebook to your sketch of poriferan anatomy. Compare the anatomy of a tunicate to that of a simple sponge. Although superficially similar in appearance, a sponge is little more than a sack of loosely connected cells with a few cells specialized for certain tasks. A tunicate, however has actual tissues and organs, and is therefore much more complex.

Consult your local field guide and see if you can find some tunicates and identify them. If they are under water, can you see the siphons working? If they are exposed (at low tide, perhaps) are their siphons closed tight? Touch them (they will not hurt you) and record your observations as to how they feel to the touch.  Do they squirt you when you touch them??? Be sure to sketch them in your notebook or take photos and put them into your notebook.(And don’t forget to share them here!)

When we were in Key Largo we had great luck looking amongst the mangrove roots for mangrove tunicates. We found tons of them and they were quite beautiful-delicate, colorful and jewel-like in appearnce. This is a strong contrast to the sea pork many folks will be seeing as their only exposure to tunicates. You really should Google image  tunicate photos so you can see the wide variety of forms.

The Fouling Community

What is that????

The fouling community is the group of organisms that in combination conspire to make a sailor’s life difficult. Well, maybe that isn’t their intent, but it sure is the effect!

The fouling community are actually organisms that are found on docks, piers, boats, and any other underwater structure, busily eating away and dragging them down, causing many millions of dollars of damage every year. They typically include tunicates, bryozoans, mollusks, barnacles, polychaetes, sea anemones, hydras, algae of all sorts, bacteria, fungi, and many other organisms.

The thing is, these are the same communities found on natural structures, it’s just that they are called the “fouling community” only when they occur on man-made structures and have the potential to cause damage, or “foul” things up.


Your task in studying the fouling community is to find a dock, piling, boat, buoy,etc that has an easily accessible fouling assemblage, and complete a survey of that community.

By “survey” I mean to make a list of the type of species, and the approximate number of members of each species in the community.You should also make a scale drawing of the assemblage in your notebook. A good way to do this is to measure out a  representative square area  of your community and use graph paper to make the scale drawing. Make notes on what you see as far as behaviors, predation, etc. in order to understand the relationships amongst these organisms. This is a project that should challenge you to make use of all of the identification practice you’ve had so far!

To inspire you, here is a link to a really neat YouTube video that shows fouling communities on various items pulled out of the North Pacific Gyre (remember that???) during a scientific study of the huge trash accumulation in the area:Project Kaisei, barnacle buoy.

In fact, I recommend taking a look at all of  the fascinating Project Kaisei work at their website and their YouTube channel.

Good stuff!!!



  1. These are great T, thanks so much! Violet is working on project week right now, so we’ll tackle this after Easter 🙂

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