Analucia Hi, I think the raphe, regardless of type, does not limit or stimulates the life form of diatoms. I do not know your project and perhaps the question would be channeled from some other angle, but the approach looks attractive and if you are interested we could continue or expand the discussion. Greetings, Rosaluz

thank you for your answer, I was curious to this topic because I read in a paper, I would like to discuss this topic the weekend, thank for help me =) Greetings, Analucía

The raphe structure is a channel in the valve of some diatom and is associated with gliding motility. Centric diatoms do not have a raphe, only certain pennate forms. A raphe may appear on only one valve of the frustule or more commonly on both. Epipelic diatom are generally biraphid and are capable of very controlled migration in the surface of the sediment they colonise, many papers describe this locomotion. Round, in his book on the alage is a very useful source.

Thanks you Mr. David Paterson

Hi Analucia

"Do diatoms that have raphe pertain only to plankton?"

Raphid diatoms are found both in water coulmn (& surface) as well as on (& in) the sediments. They are, however, specialized in making gliding movements over any substratum with the help of their raphe & associated structures. On the other hand the centric ones are better adapted when it is the question of floating around. Therefore, raphid diatoms are more abundant in/ on sediments & other substratum based media than that of the centric ones which are specialized in floating around.

The second part of your question is not clear to me. Can you elaborate?

Best

Dola

thanks you so much for your answer Dola, now I understand it, about my second question I thought that the raphe had many shapes depending of substrate where they living.

Hi Analucia

Raphid diatoms can be segregated into groups based on the the situation & shape of the raphe, like, monoraphids, eunotids, naviculoides, nitzchoids and so on.

Best

Dola

Interesting!!! Thank you very much!!