The Influence of Vertical Aspects in the Background on Camouflage

 

Home

 

 

The majority of research done on the effects of different backgrounds on cuttlefish camouflage looks solely at the horizontal background. Until Barbosa, Litman, and Hanlon conducted their experiment, very little research had been conducted looking at the influence of the vertical background on cuttlefish camouflage. Thus, these scientists tried to determine whether the vertical background had any impact on which body patterns cuttlefish chose to display. They hypothesized that vertical components in the environment would indeed have an effect on the choice of camouflage pattern since cuttlefish are benthic organisms and must deceive predators hunting them from both above and beside them (Barbosa et al., 2008). In this particular research, 2 experiments were conducted. The first was to determine whether the visual background caused a change in camouflage pattern in the cuttlefish. The second was to determine if either a vertical or horizontal background cue alone was more, less, or equally influential in promoting camouflage than a combination of vertical and horizontal cues.

 

Introduction
Camouflage Patterns
Choosing the best camouflage
Vertical Aspects in background
Predator Evasion
Color Blindness
Camouflage in Juveniles
Night Camouflage
Literature Cited
External Links

 

Methods:

In the first experiment, Barbosa, Litman, and Hanlon conducted, they used 8 European cuttlefish (Sepia officinalis) and exposed them to 3 different environments (see Figure 3). One environment was the CheckBlack substrate in which the floor was black and white checkered and the walls were solid black. The second environment was GrayCheck in which the floor was gray and the walls were black and white checkered. The third substrate was the GrayBlack in which the floor was gray and the walls were black. The response of the cuttlefish was observed, photos were taken (see Figure 5), and the average disruptive scores were determined and graphed (see Figure 6). In the second experiment, 9 European cuttlefish were exposed to 4 different environments (see Figure 4). The first substrate was the CheckCheck in which both the floor and walls were checkered. The second was the BrownCheck in which the floor was solid brown and the walls were checkered. The third substrate was CheckBrown in which the floor was checkered and the walls were solid brown. The final environment was BrownBrown in which both the floor and walls were solid brown. The response of the 9 cuttlefish was observed, photos were taken (see Figure 7) and the average disruptive scores were determined and graphed (see Figure 8).

methods1

Figure 3. Reproduced with permission from Dr. Hanlon. The three different substrates the cuttlefish were exposed to in Experiment 1 (Barbosa et al., 2008).

methods2

Figure 4. Reproduced with permission from Dr. Hanlon. The four different substrates the cuttlefish were exposed to in Experiment 2 (Barbosa et al., 2008).

 

The Results:

They found that high contrast, non-uniform backgrounds are responded to with priority over uniform backgrounds (see Figures 5 and 6). They also found that there were distinct differences in the response to checkered walls, floor, and the combination of both (see Figures 7 and 8). This suggests that cuttlefish do incorporate both vertical and horizontal cues to help them display the most appropriate camouflage pattern (Barbosa et al., 2008).

 

exp1pics

Figure 5. Reproduced with permission from Dr. Hanlon. Camouflage patterns displayed by Sepia officinalis on the 3 different backgrounds in Experiment 1. These images qualitatively show that the cuttlefish displayed a disruptive pattern when exposed to a checkered stimuli on either the floor or wall. When no checkered background was present, the cuttlefish displayed a uniform camouflage pattern. These results suggest that cuttlefish respond more strongly to a high-contrast non-uniform background, such as a checkerboard, than a uniform background (Barbosa et al., 2008).

graphexp1

Figure 6. Reproduced with permission from Dr. Hanlon. Disruptive score of Sepia officinalis on the 3 different backgrounds in Experiment 1. This graph shows the average disruptive scores the cuttlefish displayed on either CheckBlack, GrayCheck, or GrayBlack backgrounds. The disruptive score is simply the degree to which the cuttlefish displayed disruptive patterning. The cuttlefish strongly displayed disruptive patterning when they experienced checkered stimuli in either the horizontal or vertical environment. Thus, this shows that cuttlefish do respond to vertical visual stimuli in their environment. Furthermore, the cuttlefish had a very low disruptive score on the uniform GrayBlack background, showing that cuttlefish respond more strongly to the checkered backgrounds (Barbosa et al., 2008).

 

resultphotos

Figure 7. Reproduced with permission from Dr. Hanlon. Camouflage patterns displayed by Sepia officinalis on the 4 different backgrounds in Experiment 2. These images qualitatively show that the cuttlefish displayed a disruptive pattern when the checkered background was on either the wall (BrownCheck), floor (CheckBrown), or both (CheckCheck). A uniform pattern was displayed on the brown wall/brown floor (BrownBrown) environment. These images show that the strongest disruptive pattern was displayed on the checkered wall and floor background. (Barbosa et al., 2008).

verticalgraph

Figure 8. Reproduced with permission from Dr. Hanlon. Disruptive score of cuttlefish on varying backgrounds. This graph shows the average disruptive scores the cuttlefish displayed on the 4 different backgrounds they were placed on. This graph shows that the highest disruptive score was obtained when the cuttlefish were placed in the checkered wall/checkered floor environment. The cuttlefish still displayed the disruptive pattern rather strongly when only the wall was checkered, thus suggesting that vertical aspects in the cuttlefish's environment do have an impact on their choice of patterning. When the cuttlefish were placed on a uniform brown background, it barely displayed disruptive patterning, showing that cuttlefish respond more strongly to a high-contrast non-uniform background, such as a checkerboard, than a uniform background (Barbosa et al., 2008).

 

 

 

 

Hot Topics in Animal Physiology
Davidson College Home