Real world problem solving

Here is a fun looking paper where ants have been set a series of physical problems (path choice, door pushing and barrier avoidance). Perhaps unsurprisingly, ants (as clever critters) as adept at ‘solving’ these real-world challenges.

The pdf is available here: <http://www.ccsenet.org/journal/index.php/ijb/article/view/67868/36990&gt;

Abstract: “Aiming to know the extent of the ants’ cognitive abilities, we set Myrmica ruginodis workers in four problematic situations. We discovered that these ants could walk round a barrier, by foraging and navigating as usual, using known visual cues. They could walk preferentially on smooth substrates instead of rough ones, but did not memorize their choice. This behavior may be due to the easier deposit of pheromones on a smooth substrate. The ants could establish a single way when having only two narrow paths for going in and out of their nest. This was the consequence of the ants’ traffic and of the distinct pheromonal deposits while going in and out of the nest. The oldest ants needing sugar water could push a door for getting such water. They did so by having the audacity to go on walking, whatever the presence of a door. Such a door is not a tool sensu stricto. Future studies will examine if ants can lean new techniques, can use tools and/or can learn using tools.”

Cammaerts, M. C. (2017). Ants’ Ability in Solving Simple Problems. International Journal of Biology, 9(3), 26.

Skylines for navigation

A lovely paper here with some really nice behavioural experiments. Towne et al., have a long history of studying the use of skyline cues for navigation, almost 10 years ago they showed the important connection between the skyline and the compass system of bees. Here they look at the use of skyline cues for navigation, where learnt visual cues are used for setting a familiar direction. Using a small white arena they replicate a familiar skyline using black paint to create a silhouette. Bees are happy to set their direction relative to this artificial skyline even when it indicates a direction perpendicular or opposite to their normal homeward flight direction. Thus we now have good evidence that for bees, as for ants, the skyline is a sufficient source of information for navigation.

Another significant implication of this paper is that we can probe the visual knowledge of bees, that have foraged in natural complex environments, using a small scale and simple (elegant) experimental procedure. This could be a really powerful method.

Towne, W. F., Ritrovato, A. E., Esposto, A., & Brown, D. F. (2017). Honeybees use the skyline in orientation. Journal of Experimental Biology, jeb-160002.

Long-term retention of skyline memories

Ants foragers live short lives but within that they must pack a lot in. Foraging drives navigation skills which require specific types of memory, the memory for panoramic scenes being one such navigational memory. Here, Freas et al., show that ants can remember navigationally useful panoramic scenes for over 5 days, which is longer than their average foraging life.

Freas, C. A., Whyte, C., & Cheng, K. (2017). Skyline retention and retroactive interference in the navigating Australian desert ant, Melophorus bagoti. Journal of Comparative Physiology A, 1-15.

Positional control via optic flow

Some of the most famous bee experiments in navigation and positional control involve bees flying down tunnels. The striped side walls of said tunnels have been used to demonstrate the optic flow input to odometry and the flow speed control of position. However, what happens when the tunnels become wider and walls are further away; Much more like a natural object distribution. Here, Linander et al., show that in wider tunnels, bees use ventral optic flow to control a straight path. This suggests a system where optic flow from different parts of the flow field can be used for the same tasks.

Linander, N., Baird, E. & Dacke, M. J Comp Physiol A (2017). How bumblebees use lateral and ventral optic flow cues for position control in environments of different proximity. doi:10.1007/s00359-017-1173-9

Site fidelity as a universal navigation strategy

Amblypygids (whip spiders) live in complex densely vegetated environments. They forage in near complete darkness using navigational mechanisms that are yet to be elucidated. Although this paper doesn’t clear up the navigational mystery, it does demonstrate an important behavioural property that relates to the constraints that promote certain navigational skills. These invertebrates use shelters as a refuge and in lab experiments they show fidelity to a particular shelter. Site fidelty (and route fidelity) seem to be universal behavioural biases, which presumably, for many organisms,  facilitate the use of universal navigation strategies such as Path Integration and memory of sensory signatures.

Graving, J.M., Bingman, V.P., Hebets, E.A. et al. J Comp Physiol A (2017). doi:10.1007/s00359-017-1169-5

Sensory adaptations for foraging

Abstract: ” Individual differences in response thresholds to task-related stimuli may be one mechanism driving task allocation among social insect workers. These differences may arise at various stages in the nervous system. We investigate variability in the peripheral nervous system as a simple mechanism that can introduce inter-individual differences in sensory information. In this study we describe size-dependent variation of the compound eyes and the antennae in the ant Temnothorax rugatulus. Head width in T. rugatulus varies between 0.4 and 0.7 mm (2.6–3.8 mm body length). But despite this limited range of worker sizes we find sensory array variability. We find that the number of ommatidia and of some, but not all, antennal sensilla types vary with head width.

The antennal array of T. rugatulus displays the full complement of sensillum types observed in other species of ants, although at much lower quantities than other, larger, studied species. In addition, we describe what we believe to be a new type of sensillum in hymenoptera that occurs on the antennae and on all body segments. T. rugatulus has apposition compound eyes with 45–76 facets per eye, depending on head width, with average lens diameters of 16.5 μm, rhabdom diameters of 5.7 μm and inter-ommatidial angles of 16.8°. The optical system of T. rugatulus ommatidia is severely under focussed, but the absolute sensitivity of the eyes is unusually high.

We discuss the functional significance of these findings and the extent to which the variability of sensory arrays may correlate with task allocation.”

Fiorella Ramirez-Esquivel, Nicole E. Leitner, Jochen Zeil, Ajay Narendra, The sensory arrays of the ant, Temnothorax rugatulus, Arthropod Structure & Development, doi.org/10.1016/j.asd.2017.03.005.

What visual computations for robot place recognition?

For many years (over 20 I guess) Ralf Möller and collaborators have been working on visual navigation for robots. This has incorporated bio-inspired navigation algorithms and computational models of ant-like visual systems for navigation using terrestrial visual cues. One of the notable things across many of these papers is that the introduction sections are great resources for roboticists and biologists, acting as they do as mini-reviews detailing the major classes of robotic methods for specific problems. This paper is no exception, the question is: How good are different visual methods at place recognition, a problem for animals and robots alike.

Horst and Möller (2017) Visual Place Recognition for Autonomous Mobile Robots. Robotics 2017, 6(2), 9; doi:10.3390/robotics6020009