Disruptive coloration and habitat use by seahorses

Abstract

Predation avoidance is a primary factor influencing survival. Therefore, any trait that affects the risk of predation, such as camouflage, is expected to be under selection pressure. Background matching (homochromy) limits habitat use, especially if the habitat is heterogeneous. Another camouflage mechanism is disruptive coloration, which reduces the probability of detection by masking the prey’s body contours. Here we evaluated if disruptive coloration in the longsnout seahorse, Hippocampus reidi, allows habitat use diversification. We analyzed 82 photographs of animals, comparing animal and background color, and registering anchorage substrate (holdfast). We tested whether the presence (disruptive coloration) or absence of bands (plain coloration) predicted occupation of backgrounds of different colors. We also calculated the connectance between seahorse morph and background color or holdfast, as well as whether color morph differed in their preferences for holdfast. Animals with disruptive coloration were more likely to be found in environments with colors different from their own. Furthermore, animals with disruptive coloration occupied more diversified habitats, but as many holdfasts as plain colored animals. Therefore, animals with disruptive coloration were less selective in habitat use than those lacking disruptive color patterns, which agrees with the disruptive coloration hypothesis.

The consistent background color preference highlights the personality in the lined seahorse, Hippocampus erectus

“…Obviously, the hypothesis does not apply to the lined seahorse, because the tested seahorses were the black in body color, and 90.6% of the seahorses showed black color avoidance in the present study. Seahorses, a group of habitat mimicry or crypsis species, can rapidly translate the color that they see in the surroundings and accurately display the color through the skin (Stevens and Merilaita, 2011;Duarte et al, 2019). We inferred that the lined seahorses may adapt themselves to the color in nature or cultured environment, The bold-shy axis of the lined seahorse identified on the basis of personality score by the principal components analysis (PCA) (N = 31).…”

Sphingid caterpillars conspicuous patches do not function as distractive marks or warning against predators

“…Disruptive coloration works to decrease recognition of prey by obstructing the outline (Stevens & Merilaita, 2009 ), whereas distractive marks work to draw attention to the markings instead of the prey's outline (Stevens, Troscianko, et al, 2013 ). A few studies have found support for the disruptive color hypothesis (Cuthill et al, 2005 ; Duarte et al, 2019 ; Stevens et al, 2006 ) and distractive marks (Dimitrova et al, 2009 ; Olofsson et al, 2013 ) in decreasing predation risk. However, Stevens, Graham, et al ( 2008 ) did not find support for the distractive marks hypotheses and empirical testing for the distractive marks hypothesis is lacking.…”