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Ant Homing Ability Is Not Diminished When Traveling Backwards.

Ardin PB, Mangan M, Webb B - Front Behav Neurosci (2016)

Bottom Line: It is possible that ants use initial or intermittent retinotopic alignment, coupled with some other direction stabilizing cue that they can utilize when moving backward.However, though most ants dragging prey would occasionally look toward the nest, we observed that their heading direction was not noticeably improved afterwards.We assume ants must use comparison of current and stored images for corrections of their path, but suggest they are either able to chose the appropriate visual memory for comparison using an additional mechanism; or can make such comparisons without retinotopic alignment.

View Article: PubMed Central - PubMed

Affiliation: Insect Robotics Lab, School of Informatics, University of Edinburgh Edinburgh, UK.

ABSTRACT
Ants are known to be capable of homing to their nest after displacement to a novel location. This is widely assumed to involve some form of retinotopic matching between their current view and previously experienced views. One simple algorithm proposed to explain this behavior is continuous retinotopic alignment, in which the ant constantly adjusts its heading by rotating to minimize the pixel-wise difference of its current view from all views stored while facing the nest. However, ants with large prey items will often drag them home while facing backwards. We tested whether displaced ants (Myrmecia croslandi) dragging prey could still home despite experiencing an inverted view of their surroundings under these conditions. Ants moving backwards with food took similarly direct paths to the nest as ants moving forward without food, demonstrating that continuous retinotopic alignment is not a critical component of homing. It is possible that ants use initial or intermittent retinotopic alignment, coupled with some other direction stabilizing cue that they can utilize when moving backward. However, though most ants dragging prey would occasionally look toward the nest, we observed that their heading direction was not noticeably improved afterwards. We assume ants must use comparison of current and stored images for corrections of their path, but suggest they are either able to chose the appropriate visual memory for comparison using an additional mechanism; or can make such comparisons without retinotopic alignment.

No MeSH data available.


Related in: MedlinePlus

Ant homing. (A) Recorded ant paths, with head-tail orientation shown via color-coding for ants without food (top) and ants carrying prey (middle and bottom), and (B) mean vectors for each path for direction of movement and head-tail orientation. The mean direction for ants with or without food is almost identical (no food: mean 0.92 ± 56.40 degrees; with food (mixed orientations): mean 1.50 ± 68.94 degrees; with food (facing away from the nest): mean 1.80 ± 61.72 degrees) but the head-tail orientation is strikingly different (no food: mean 2.11 ± 47.32 degrees; with food (mixed orientations): mean 72.62 ± 131.88 degrees; with food (facing away from the nest): mean −177.59 ± 66.17 degrees). Below each path is shown the percentage of time the ant was moving backwards.
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Figure 2: Ant homing. (A) Recorded ant paths, with head-tail orientation shown via color-coding for ants without food (top) and ants carrying prey (middle and bottom), and (B) mean vectors for each path for direction of movement and head-tail orientation. The mean direction for ants with or without food is almost identical (no food: mean 0.92 ± 56.40 degrees; with food (mixed orientations): mean 1.50 ± 68.94 degrees; with food (facing away from the nest): mean 1.80 ± 61.72 degrees) but the head-tail orientation is strikingly different (no food: mean 2.11 ± 47.32 degrees; with food (mixed orientations): mean 72.62 ± 131.88 degrees; with food (facing away from the nest): mean −177.59 ± 66.17 degrees). Below each path is shown the percentage of time the ant was moving backwards.

Mentions: All 20 displaced ants returned directly to the nest irrespective of whether they were carrying food or not (Figure 2A). Although the ants had some path integration information, indicating the nest lay either north or south, there was no consistent deviation in their initial headings corresponding to this vector direction (Supplementary Material 1).


Ant Homing Ability Is Not Diminished When Traveling Backwards.

Ardin PB, Mangan M, Webb B - Front Behav Neurosci (2016)

Ant homing. (A) Recorded ant paths, with head-tail orientation shown via color-coding for ants without food (top) and ants carrying prey (middle and bottom), and (B) mean vectors for each path for direction of movement and head-tail orientation. The mean direction for ants with or without food is almost identical (no food: mean 0.92 ± 56.40 degrees; with food (mixed orientations): mean 1.50 ± 68.94 degrees; with food (facing away from the nest): mean 1.80 ± 61.72 degrees) but the head-tail orientation is strikingly different (no food: mean 2.11 ± 47.32 degrees; with food (mixed orientations): mean 72.62 ± 131.88 degrees; with food (facing away from the nest): mean −177.59 ± 66.17 degrees). Below each path is shown the percentage of time the ant was moving backwards.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4829585&req=5

Figure 2: Ant homing. (A) Recorded ant paths, with head-tail orientation shown via color-coding for ants without food (top) and ants carrying prey (middle and bottom), and (B) mean vectors for each path for direction of movement and head-tail orientation. The mean direction for ants with or without food is almost identical (no food: mean 0.92 ± 56.40 degrees; with food (mixed orientations): mean 1.50 ± 68.94 degrees; with food (facing away from the nest): mean 1.80 ± 61.72 degrees) but the head-tail orientation is strikingly different (no food: mean 2.11 ± 47.32 degrees; with food (mixed orientations): mean 72.62 ± 131.88 degrees; with food (facing away from the nest): mean −177.59 ± 66.17 degrees). Below each path is shown the percentage of time the ant was moving backwards.
Mentions: All 20 displaced ants returned directly to the nest irrespective of whether they were carrying food or not (Figure 2A). Although the ants had some path integration information, indicating the nest lay either north or south, there was no consistent deviation in their initial headings corresponding to this vector direction (Supplementary Material 1).

Bottom Line: It is possible that ants use initial or intermittent retinotopic alignment, coupled with some other direction stabilizing cue that they can utilize when moving backward.However, though most ants dragging prey would occasionally look toward the nest, we observed that their heading direction was not noticeably improved afterwards.We assume ants must use comparison of current and stored images for corrections of their path, but suggest they are either able to chose the appropriate visual memory for comparison using an additional mechanism; or can make such comparisons without retinotopic alignment.

View Article: PubMed Central - PubMed

Affiliation: Insect Robotics Lab, School of Informatics, University of Edinburgh Edinburgh, UK.

ABSTRACT
Ants are known to be capable of homing to their nest after displacement to a novel location. This is widely assumed to involve some form of retinotopic matching between their current view and previously experienced views. One simple algorithm proposed to explain this behavior is continuous retinotopic alignment, in which the ant constantly adjusts its heading by rotating to minimize the pixel-wise difference of its current view from all views stored while facing the nest. However, ants with large prey items will often drag them home while facing backwards. We tested whether displaced ants (Myrmecia croslandi) dragging prey could still home despite experiencing an inverted view of their surroundings under these conditions. Ants moving backwards with food took similarly direct paths to the nest as ants moving forward without food, demonstrating that continuous retinotopic alignment is not a critical component of homing. It is possible that ants use initial or intermittent retinotopic alignment, coupled with some other direction stabilizing cue that they can utilize when moving backward. However, though most ants dragging prey would occasionally look toward the nest, we observed that their heading direction was not noticeably improved afterwards. We assume ants must use comparison of current and stored images for corrections of their path, but suggest they are either able to chose the appropriate visual memory for comparison using an additional mechanism; or can make such comparisons without retinotopic alignment.

No MeSH data available.


Related in: MedlinePlus