# behav: mechanics of fire ant rafts as an active self-healing membrane

<< The unique ability of fire ants to form a raft to survive flooding rain has enchanted biologists as well as researchers in other disciplines. (..) a three-dimensional aggregation of fire ants exhibits viscoelasticity with respect to external compression and shearing among numerous unusual mechanical properties. >>️

AA << study the ant raft in its natural form, i.e., composing no more than two layers. This allowed to focus on the cracks that are unique to membranes and see how their patterns are influenced by the fact that these ants are mobile and can self-repair the damage to keep their raft from disintegration. >>️

They << show that vertical and horizontal shaking can also prompt fire ants to aggregate.  (..)  the pull force expedites the alignment of fire ants, in analogy to the effect of an electric field on liquid crystal polymers. >>️

<< One major finding is that the raft can exhibit zero Poisson's ratio without resorting to specific geometry structures. This is enabled by the active recruitment of ants from the top layer to the bottom layer to keep the raft from disintegrating. >>️

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Chung-Hao Chen, Ting-Heng Hsieh, et al. Formation and mechanics of fire ant rafts as an active self-healing membrane. Phys. Rev. E 109, 014607. Jan 9, 2024. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.014607

David Ehrenstein. Material Properties of Fire-Ant Rafts. Physics 17, s5. Jan 9. 2024. 

https://physics.aps.org/articles/v17/s5

Also:  raft   https://flashontrack.blogspot.com/search?q=raft  

zattera (quasi-stochastic poetry) https://inkpi.blogspot.com/2005/04/1864-onda-di-liberazione.html  

randa (quasi-stochastic poetry) https://inkpi.blogspot.com/search?q=randa

Also: behav, behavior, in  https://www.inkgmr.net/kwrds.html

Keywords behavior, behaviour, ant, raft, self-healing

# behav: backward walking, navigational uncertainties (among Cataglyphis velox)

<< Current opinion in insect navigation assumes that animals need to align with the goal direction to recognise familiar views and approach it. Yet, ants sometimes drag heavy food items backward to the nest and it is still unclear to what extent they rely on visual memories while doing so. >>

<< ants do indeed recognise and use the learnt visual scenery to guide their path while walking backward. In addition, the results show that backward homing ants estimate their directional certainty by combining visual familiarity with other cues such as their path integrator and the time spent backward. >>

Sebastian Schwarz, Leo Clement, et al.  How do backward walking ants (Cataglyphis velox) cope with navigational uncertainty? doi: 10.1101/2019.12.16.877704. Dec 17, 2019.

https://www.biorxiv.org/content/10.1101/2019.12.16.877704v1