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I went to Goleta Beach today to pick up some kelp for my science lesson this week. I found some really neat holdfast at the end of a mass of kelp! I cut it off to take that home. I have attached a few photos of it. Could either of you tell me more about it? It makes sense that the holdfast would be on the ocean floor. But I wonder about the shells attached. Do either of you know what kind of sea creature that this type of shell is from? These shells are also all over the beach. Is it typical for shelled sea animals to be underneath the holdfast of kelp? I'm interested in doing an inquiry type lesson with my class (for social studies) in addition to my science lesson, but I'd like to know more about what I found. This structure is very interesting!
Question Date: 2008-05-27
Answer 1:

OK , Kelp I know, but I am out of my depth here and the pictures do not tell me what I need to know - It almost looks like the hold fast has a set of tube worms as the flat plate-like structure and then there are some clams attached. In addition, there are some blue-grey bits that look like pieces of the Pliocene Sisquoc Formation. I can say that, once a kelp has a hold fast in place, indeed marine invertebrates will settle on it as a sold place of attachment, but I do not recognize the flat plate like structure.

Best to you

Answer 2:

Yes, holdfasts are commonly attached to other organisms.There are also many organisms that live in and erode holdfasts. Some actually bore into the holdfast but others are just nestlers, living in spaces made by other organisms. The clam in the pic is such a nestler. Holdfasts are rich habitats and excellent for class studies.


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