Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2014 Jan 6;369(1636):20130034.
doi: 10.1098/rstb.2013.0034. Print 2014.

Looking and homing: how displaced ants decide where to go

Jochen Zeil  1 , Ajay Narendra, Wolfgang Stürzl
Affiliations

Looking and homing: how displaced ants decide where to go

Jochen Zeil et al. Philos Trans R Soc Lond B Biol Sci. .

Abstract

We caught solitary foragers of the Australian Jack Jumper ant, Myrmecia croslandi, and released them in three compass directions at distances of 10 and 15 m from the nest at locations they have never been before. We recorded the head orientation and the movements of ants within a radius of 20 cm from the release point and, in some cases, tracked their subsequent paths with a differential GPS. We find that upon surfacing from their transport vials onto a release platform, most ants move into the home direction after looking around briefly. The ants use a systematic scanning procedure, consisting of saccadic head and body rotations that sweep gaze across the scene with an average angular velocity of 90° s(-1) and intermittent changes in turning direction. By mapping the ants' gaze directions onto the local panorama, we find that neither the ants' gaze nor their decisions to change turning direction are clearly associated with salient or significant features in the scene. Instead, the ants look most frequently in the home direction and start walking fast when doing so. Displaced ants can thus identify home direction with little translation, but exclusively through rotational scanning. We discuss the navigational information content of the ants' habitat and how the insects' behaviour informs us about how they may acquire and retrieve that information.

Keywords: Myrmecia croslandi; ants; scanning behaviour; visual homing.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Experimental area and set-up. Six release stations are shown together with the location of the nest and the nest's foraging tree on an aerial image. The typical foraging corridor for this nest is marked by blue arrows. Square insets on the right show on top the release platform with the central hole to accommodate the transport vials, a compass and a calibration pattern. Bottom inset shows an enlarged image of an ant with red circles indicating the positions on the head and the blue circle the position on the body, the x/y coordinates of which were extracted to determine head and body orientation. Inset on the bottom left shows three example paths of ants on the round release platform with a line indicating head (gaze) orientation pointing into the direction of the dots that mark the position of the front of the head every 40 ms.
Figure 2.
Figure 2.
The dynamics of ant scanning movements. (a) Gaze direction (blue), body axis orientation (red) and bearing (black) relative to the release point with the true nest direction at 0° for a 2 s segment about 3 s after the ant had entered the platform. (b) Head orientation relative to the body longitudinal axis for the same sequence. (c) Time course of the angular velocity of the head relative to the body (green), the longitudinal body axis (red) and the gaze direction (blue) during the same sequence as shown in (a,b). Open arrows mark instances when head movements compensate for body rotations and black arrows mark instances when the head rotation is followed by body rotation. Sampling rate was 200 fps. (d) The relationship between the angular velocity of the body and the angular velocity of the head relative to the body for two example sequences (top row and bottom row). Left panels: scatter diagrams of head angular velocity over body angular velocity showing overall negative correlation. Centre panels: cross-correlation between head and body angular velocities, showing zero lag for the smallest negative correlation coefficient. Right panels: two-dimensional histograms of the centre section of the scatter plots on the left, showing high frequencies of head movements compensating for body rotations (maximal values along the diagonal) and high frequencies of head movements while the body is still (maximal values along vertical at zero body angular velocity).
Figure 3.
Figure 3.
The movements and gaze directions of ants on release platforms. Five examples each of full-vector (a) and zero-vector (b) ant behaviour upon release on 10 m distant platforms. Left columns: ant paths (red lines, FV; black lines, ZV) with nest direction indicated by black arrow, the direction of the path integration vector indicated by red arrow. Centre columns: gaze directions (red lines) and bearings (green lines) relative to the true home direction at 0°. Right columns: walking speed of ants. Note that time runs from bottom to top on the vertical axis. (c) The average time ants spend on the platform at low and high walking speeds. Box plot conventions: lower whisker: 10% quartile; box bottom: first quartile; horizontal line: median; black dot: mean; box top: third quartile; top whisker: 90% quartile. Zero-vector ants (grey boxes) do not spend significantly more time walking slowly compared with the full-vector ants (red boxes). See text for the results of a statistical analysis.
Figure 4.
Figure 4.
(a) Paths of ants on release platforms 10 m from the nest (top row) and 15 m from the nest (bottom row). Black lines, zero-vector ants; red lines, full-vector ants. Nest direction is indicated by black arrow, the direction of the path integration vector (for red paths) is indicated by red arrows. (b) Gaze directions of ants on release platforms. Column 1: normalized frequency histograms of gaze directions relative to the true home direction at 0° of zero-vector ants released at 10 m (top) and at 15 m (bottom) from the nest, when walking slower than 5 cm s−1 (black lines) and faster than 5 cm s−1 (blue filled areas). Columns 2–4: same for full-vector ants, with the direction supplied by the path integrator indicated by red arrows. n indicates the number of releases at the different release stations.
Figure 5.
Figure 5.
Scanning gaze direction and the local panorama at 10 m release stations. Top row shows the nest-oriented panoramic scenes at the north (left), east (centre) and south (right) release stations oriented south, west and north, respectively. Second row shows compound gaze histograms of all zero-vector ants released at the three sites, sorted depending on whether the ants walked slower than 5 cm s−1 (black lines) or faster than 5 cm s−1 (blue filled areas). Histograms show means of individual ant histograms that were normalized to one. Path integration directions are indicated by red arrows. Blue-barred histograms are gaze directions for the whole time each of 17 individual ants spent on the platform, each released at three stations (rows 1–11) or at two stations (rows 12–17). Dashed lines at 0° indicate true nest direction. Red-barred histograms for the 10 m east release station are the gaze directions of five full-vector ants.
Figure 6.
Figure 6.
The panorama and gaze directions during fixation. Images on top show the scene at release locations 15 m north, east and south of the nest both as camera-based images (top row) and as reconstructed model views (second row, scene filtered with 3° of resolution). The nest direction is indicated by a dashed line and home vector directions by red arrow heads. Histograms show gaze directions of individual ants on the release platform for those instances when the angular velocity of gaze changed by less than 50° s−1. Blue, zero-vector ants; red, full-vector ants.
Figure 7.
Figure 7.
The panorama and gaze directions at moments when ants reverse scanning direction. (a) The panoramic scene at the nest facing south (left), west (centre) and north (right) as reconstructed within the three-dimensional model of the area. Bottom row shows the scene filtered with 3° of resolution. (b) Local panoramic views acquired from the panoramic imager (top row images) and as reconstructed in the three-dimensional model (second row images). Yellow and red lines are the rotational image difference functions at these locations relative to the nest views shown in (a). Below images: frequency histograms of gaze directions (red line histograms) at the moment of reversal of scanning direction (see red dots in (c)) at the different release sites. Blue line shows pixel values (from 0 to 255) along horizontal transects through the reconstructed views (indicated by blue dotted lines in second row of panoramas). Reversals were determined over the whole scanning period on platforms. Number of ants given as n, number of reversals as nrev. (c) Examples of gaze directions over time (time running from bottom to top along the vertical axis) at the three release sites. Reversal of scanning directions are marked by red dots.
Figure 8.
Figure 8.
Example paths of ants on the release platform (left column) and after leaving the platform at increasing scales from second to fourth column. Nest direction is indicated by dashed arrows. Red, green and blue colours label ant identity from left to right. Note that the platform paths in the second column are not always contiguous with the GPS paths, because ants often spend some time underneath the platform after moving over its edge. Top row shows three examples each of full-vector (FV) ants, whereas second and bottom row shows three examples each of zero-vector (ZV) ants. Note that all ants, except one (blue path in second row), irrespective of their status and their initial paths on the platform, eventually find their way home (open circles in fourth column panels).
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Land MF, Collett TS. 1975. Visual spatial memory in a hoverfly. J. Comp. Physiol. 100, 59–84. (10.1007/BF00623930) - DOI
    1. Cartwright BA, Collett TS. 1987. Landmark maps for honeybees. Biol. Cybernet. 57, 85–93. (10.1007/BF00318718) - DOI
    1. Vardy A, Möller R. 2005. Biologically plausible visual homing methods based on optical flow techniques. Connect. Sci. 17, 47–89. (10.1080/09540090500140958) - DOI
    1. Zeil J, Boeddeker N, Stürzl W. 2009. Visual homing in insects and robots. In Flying insects and robots (eds Floreano D, Zufferey J-C, Srinivasan MV, Ellington C.), pp. 87–100. Berlin, Germany: Springer.
    1. Zeil J, Hofmann MI, Chahl JS. 2003. Catchment areas of panoramic snapshots in outdoor scenes. J. Opt. Soc. Am. A 20, 450–469. (10.1364/JOSAA.20.000450) - DOI - PubMed

Publication types

LinkOut - more resources