Find research datasets worth reusing

Fig. 2 in The almost invisible league: crypsis and association between minute fishes and shrimps as a possible defence against visually hunting predators

Fig. 2. Three members of the almost invisible league: Priocharax ariel (top centre), Palaemonetes carteri (bottom left), Microphilypnus amazonicus (bottom right) in aquarium under artificial light. Same specimens as in Fig. 1 except for M. amazonicus (17.8 mm SL, INPA 25244).

Fig. 5. A in The almost invisible league: crypsis and association between minute fishes and shrimps as a possible defence against visually hunting predators

Fig. 5. A juvenile Centropomus mexicanus (12.9 mm SL, ZUEC 6171) gorged with eleotrid fish prey, photographed in field aquarium under artificial light.

Fig. 1 in The almost invisible league: crypsis and association between minute fishes and shrimps as a possible defence against visually hunting predators

Fig. 1. The studied igapó habitat in Amazonia (top left) with leaf-litter debris on the bottom; the eleotrid fish Microphilypnus amazonicus camouflaged on a decomposing leaf (17.5 mm SL, INPA 25244, top right), the characid fish Priocharax ariel hovering in the water column close to a dead leaf (14.3 mm SL, INPA 25243, bottom left), and the palaemonid shrimp Palaemonetes carteri crawling on a dead leaf (23. 7 mm TL, INPA 1432, bottom right). The cryptic effect of each species' colour pattern is lessened under artificial light (photographed in aquarium).

Fig. 4. A in The almost invisible league: crypsis and association between minute fishes and shrimps as a possible defence against visually hunting predators

Fig. 4. A larval Eleotris pisonis (8.8 mm SL, ZUEC 6169, left) and a juvenile Eucinostomus melanopterus (11.3 mm SL, ZUEC 5378, right) photographed in field aquarium under artificial light.

opencc-zeroJan 2022View details →

From crypsis to masquerade: ontogeny changes the colour defences of a crab spider hiding as bird droppings

Selection imposed by visually-hunting predators has driven the evolution of colour-based antipredator defence strategies such as crypsis, masquerade, mimicry and aposematism. Individuals of many animals are generally considered to rely on a single type of defence strategy, but individuals of some species use multiple colour-based defences. Many animals switch between colour-based defences against visually-hunting predators during ontogeny. However, why this occurs remains poorly understood. The crab spider Phrynarachne ceylonica is an often-cited example of a bird dropping masquerade. It has recently been demonstrated that P. ceylonica crab spiders gain protection from their predators by being misidentified as bird droppings by their predators. P. ceylonica females show an ontogenetic shift in colour defences: early instars possess a dark and cryptic form, while at later instars and as adults, the spiders resemble bird droppings. We hypothesised that this shift may be driven by differential changes in predation risk of two defence strategies with increasing body size due to ontogeny. We tested this hypothesis by presenting naïve domestic chicks with 3D printed artificial spiders of two different sizes (small, large) and two colours (dark, bird dropping-like), and determined if larger bird dropping-like spiders are more readily found and attacked than cryptic forms by chicks. We found that small cryptic spiders were more difficult to detect than small bird dropping masquerading spiders, but large cryptic spiders were attacked much more quickly and more frequently than large bird dropping masquerading spiders. Increasing predation pressure on larger, cryptic spiders during ontogeny suggests that switching to bird dropping masquerade may be a more effective defence as spiders increase in size. We thus conclude that the ontogenetic shift from crypsis to masquerade is adaptive.

opencc-zeroSep 2022View details →

Selfish herd effects depend on prey crypsis

Determining why some animals form groups while others remain solitary is a longstanding goal in behavioural ecology. Group formation can help mitigate predation risk through a variety of mechanisms, including risk dilution and group vigilance. The 'selfish herd hypothesis' proposes that prey can reduce their risk by minimizing the area around which all points in that area are closer to them than to another conspecific (i.e., by minimising their 'domain of danger'). This hypothesis assumes that an individual's predation risk is proportional to the size of its domain of danger, however, the relationship between risk and proximity to conspecifics may depend on additional factors. Specifically, approaching conspecifics may be costly for prey that rely on crypsis because group formation increases detectability. Using model prey, we experimentally manipulated prey colouration as well as the domain of danger, then tracked their 'survival' under natural field conditions. We found that an individual's predation risk increased with their domain of danger for conspicuous (red) prey, but decreased with the domain of danger in cryptic (green) prey. Our results are consistent with patterns in natural systems and indicate that the relationship between predation risk and domain of danger depends on additional factors like prey colouration.

opencc-zeroAug 2021View details →

Data from: Crypsis in the pelagic realm: evidence from exceptionally preserved fossil fish larvae from the Eocene Stolleklint Clay of Denmark

Marine deposits of earliest Eocene age in northern Jutland, Denmark, are renowned for yielding diverse teleost assemblages that have proved central for enhancing our understanding of the early evolution of many extant actinopterygian clades. In this study, we investigate diminutive larval fish fossils from the Stolleklint Clay, Ølst Formation, that retain multiple soft-tissue features preserved as distinct dark-coloured stains. In order to examine the elemental and molecular composition of these soft parts, we employed a combination of time-of-flight secondary ion mass spectrometry (ToF-SIMS), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Our analyses revealed that the preserved structures contain chemically identifiable eumelanin intimately associated with densely aggregated microbodies that are morphologically consistent with melanosome organelles. Thus, we conclude that the carbonaceous structures represent traces of originally melanized body parts, including the eyes and peritoneum. Comparable pigmentation patterns are seen in many extant teleost larvae that use semi-transparency as a means of camouflage in pelagic environments, to suggest a similar visual appearance of the Stolleklint Clay fish fossils. This in turn suggests that adaptations for concealment and UV-protection had evolved already by the beginning of the Eocene, notably during a time interval characterized by an extreme greenhouse climate, when the global fish fauna become increasingly modern in composition.

opencc-zeroDec 2022View details →

Main body part dominates crypsis in a flower-visiting spider

Camouflage is one of the most common defence strategies. Some crab spiders with uniform colouration have been demonstrated to camouflage on flowers via background matching. However, many more flower-visiting spiders do not have uniform body colour, and whether these species are cryptic on flowers needs more exploration. We investigated this question in a crab spider with a different-coloured abdomen and carapace, Ebrechtella tricuspidata, whose females and juveniles can normally be found on the flower petals of chamomile Matricaria recutita. We conducted predation experiments by using naive chicks as an avian predator of E. tricuspidata, to test whether avian predators could detect E. tricuspidata from flowers or leaves of M. recutita. We found that the probabilities of spiders that were detected and attacked were lower when the spider was on a flower petal than on a leaf, which supported the crypsis of E. tricuspidata. Furthermore, the visual modelling from the perspective of chicks showed that the spider abdomen matched the flower petal in both chromatic and achromatic contrast and was unlikely to be detected by avian predators. Taken together, our results indicate that E. tricuspidata is cryptic on chamomile flowers and has a much lower predation risk than on leaves. Importantly, E. tricuspidata is more representative than the species with uniform colouration. Thus, these findings highlight that camouflage may be widespread in flower-visiting spiders.