Flight

Check this out. Lots of nice and close up pictures of various insects. Kudos to the photographer!

Today I review a paper not directly related to physics. We were fortunate to have Robert Dudley from Berkeley give the colloquium talk on 11/1/2006 here. Here's one of the works he described.

Yanoviak, S.P., Dudley, R. and M. Kaspari. 2005. "Directed aerial descent in arboreal ants." Nature 433:624-626

This study looked at how tropical arboreal ants were able to control their fall from the mother tree in such a way as to land on the tree trunk before hitting the forest ground. The ants were capable of directing their aerial descent with 80% chance of returning to their mother tree.

This is interesting because these ants must obviously have precise control over their bodies as they fall. In fact, the ability to return to the tree before hitting forest ground is an important survival mechanism. On occasion the ant may accidentally fall from the tree or sometimes purposefully jump to avoid predators; if they hit the forest ground and become lost or removed from the colony, they will not survive.

Dudley and coworkers determined the ants are able to distinguish their trees largely due to contrast in the long white strips of the tree trunk from the green forest background. Thus, it seems that long linear (but not necessarily horizontal!) bright colors on top of a green forest background are important visual cues for the ants to find their way home. Interestingly, the ants fall backwards with their abdomens first. Their eyes are in the rear capable of seeing with nearly 180 degree view. In this particular species, (as Dudley mentioned in his talk) the ants have small structures on their heads that are like tail wings that serve as stabilizers to direct the descent.

It is known that non-winged aerial behaviour existed before winged flight. Thus, it seems likely that wings and thus, flight, evolved from the species that developed abilities to maneuver successfully in air.

The data below simply shows a trace for a directed aerial descent in the Cephalotes atratus L. (Hymenoptera: Formicidae) ant, and also interesting data showing that ants with smaller mass had more maneuverability.

Taken from Nature article.