I am trying to make a simplified model of the movement of meiofaunal animals in marine sediments.
Depending on their mode of movement, meiofauna can be classified as either "interstitial" (i.e. they move through sediment particles) or "burrowing" (i.e. they displace particles to move).
The organisms I am interested in, the kinorhynchs, move by anchoring an eversible introvert armoured with hook-like structures (scalids) in the sediment and actively pulling on them. That means that the locomotion of these animals mainly relies on the resistance offered by the sediment matrix in response to the force exerted by the scalids. Thus, it should be possible to make a study of momentum or quantity of movement with the weight of these organisms and the weight of the sediment through which they move. This could help us better understand how these animals move and how they are distributed according to the granulometry of the sediment.
However, this "model" becomes more complicated in fine sediments. It is relatively acceptable to assume that the resistance offered by coarse sediments, such as sand or gravel, is primarily due to the weight of the particles, and other minor forces exerting extra resistance can be neglected (for the purposes of this model). However, in fine sediments the resistance to displacement is (possibly) not exerted only by the weight of the particles, but is much greater than the sum of the weights of the grains due to other elements such as electrostatic forces between particles (and possibly others).
My questions are:
1. Are these assumptions correct?
2. Is there any way to calculate the resistance of fine sediments to the movement of these animals comparable to the resistance exerted by sandy sediments due to the weight of their particles?
Comments, suggestions or related literature are welcome.
Thank you very much,
Alberto.
The resistance to movement of fine sediments, such as silt or clay, can be calculated using empirical formulas like the Shields equation, which considers factors such as sediment size, density, and critical shear stress. Laboratory tests, such as direct shear tests, can provide more precise measurements under controlled conditions, enhancing the accuracy of calculations.