Small organisms living in the ocean that have stages of life cycles sometimes have a planktonic stage. When this planktonic form is a drifter covered in cilia, what could be all the possible uses of the cilia to this form (bearing in mind that they are drifters and thus can not swim very long on their own)?
Hi Dominique
Yes they are not effective swimmers, but then they use their cilia to sweep food right into the mouth (suspension feeders) and for movement (swimming, ineffective though!).
Best
Dola
Ok... feeding acceptable... Then what would we think when we consider larval forms that are ciliated and have nutritional supplies? I understand they swim to some extent, but is there more to it than meets the eye?
Could be... but before that you may please look into some classical text books in zoology. I loved the book called 'Invertebrates' by Barrington and there are several others.
I have read through and it is this which fascinates me. More than morphology, do you have any info on behavioral zoology?
There is a book called 'Instinctive living' by TH Savory; then there is 'Studies in Invertebrate Behaviour' by Stewart Martin Evans; then there is another called 'Invertebrate Learning' by Abramson. And again 'Invertebrates' by Barrington is my favorite.
Cilia could also be used as a sensory system, to feel movement in the water around them. and also for defense, depending on the size of the predator.
Why do you think, that they are so ineffective swimmers? At least swimming is needed to get to the current...and to get out of it, for settlement. For many animals swimming by cilia is a must simply to stay floating-veligers for example. And yes, cillia are used as a sensory system, mainly for searching for appropriate place for settlement.
Dear Domonique,
In the attached paper I discussed potential uses of cilia by the sponge larva with "purposes" other than effective displacement.
Dear Domonique,
Please, check the attached file to see how sponge larvae can use their cilia for several functions.
Dominique:
When you are drifting with the currents, food may become depleted locally. A bacteria can rely on diffusion to replenish its surroundings but a larger organism cannot. It thus needs to move around within its drifting current mass to find a new patch with more food. Other small organisms use turbulence to do that, or let themselves sink a little changing their internal density. But everybody larger than a bacteria in the pelagic milieu needs to move relative to its surroundings to find a more concentrated patch of food (a cow cannot stay in one place and wait for the grass to grow back; it needs to move!). This information is found in general textbooks such as Barnes' marine ecology, an in other texts on low Reynolds number organisms living in fluid media.
Sven
Hi, Dominique,
There is a classic text with great discussions of the multiple topics involved. It is Air and Water: The Biology and Physics of Life's Media, by Mark W. Denny (Princeton Univ. Press, 1993), ISBN 0-691-08734-2. Cheers, Vince
Ciliated larvae swim fast enough to affect their vertical position significantly. This in turn allows them to in effect sample the horizontal currents of different water layers and thus affect their horizontal position. Many of the larvae also feed on phytoplankton using the beating of their cilia.
@ Simon: It is an interesting thing in relation to the work that I'm doing that larvae feed on phytoplankton in the currents... Because benthic larvae can be carried for such long distances due to enhanced survival! Nature's conveyor belt... :-)
Dear Sven,
Your description of it all makes me feel like i'm in the ocean myself! I understand these movements and yes, I see how it is possible as I have seen them moving to and fro under the microscope in search of food once the supplies are dry. They are quite fast at their own size scale which is a point I need to clarify... Survival of the fittest is something I'm interested in and it seems to me that if they can feed as they move along in the current that they could probably survive quite a long ride!
Dominique.
Dear Sven,
Viscosity was something that I was working on about a year ago with relation to copepod movement and how it affected energy consumption during diel vertical migration. Also there was a confusion regarding the variation of viscosity with depth in the ocean and its significance for organisms at low Reynolds numbers.
Dominique.
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