Aggressive mimicry

Aggressive mimicry describes predators (or parasites) which share the same characteristics as a harmless species, allowing them to avoid detection by their prey (or host). The mimic may resemble the prey or host itself, or another organism which is either neutral or beneficial to the signal receiver. In this class of mimicry the model may be affected negatively, positively or not at all. Just as parasites can be treated as a form of predator,[44] host-parasite mimicry is treated here as a subclass of aggressive mimicry. The mimic may have a particular significance for duped prey. One such case is spiders, amongst which aggressive mimicry is quite common in both luring prey and stealthily approaching predators.[45] One case is the Golden Orb Weaver (Nephila clavipes), which spins a conspicuous golden colored web in well-lit areas. Experiments show that bees are able to associate the webs with danger when the yellow pigment is not present, as occurs in less well-lit areas where the web is much harder to see. Other colors were also learned and avoided, but bees seemed least able to effectively associate yellow pigmented webs with danger. Yellow is the color of many nectar bearing flowers, however, so perhaps avoiding yellow is not worth while. Another form of mimicry is based not on color but pattern. Species such as Argiope argentata employ prominent patterns in the middle of their webs, such as zigzags. These may reflect ultraviolet light, and mimic the pattern seen in many flowers known as nectar guides. Spiders change their web day to day, which can be explained by bee's ability to remember web patterns. Bees are able to associate a certain pattern with a spatial location, meaning the spider must spin a new pattern regularly or suffer diminishing prey capture.[46] Another case is where males are lured towards what would seem to be a sexually receptive female; the model in this situation being the same species as the dupe. Beginning in the 1960s, James E. Lloyd's investigation of female fireflies of the genus Photuris revealed they emit the same light signals that females of the genus Photinus use as a mating signal.[47] Further research showed male fireflies from several different genera are attracted to these "femmes fatales", and are subsequently captured and eaten. Female signals are based on that received from the male, each female having a repertoire of signals matching the delay and duration of the female of the corresponding species. This mimicry may have evolved from non-mating signals that have become modified for predation.[48] Chlorobalius leucoviridis mimicry of Kobonga oxleyi MENU0:00 Kobonga oxleyi cicada song with reply clicks from a Chlorobalius leucoviridis Chlorobalius leucoviridis mimicry of Pauropsalta sp. MENU0:00 Pauropsalta sp. "Sandstone" song with reply clicks from a Chlorobalius leucoviridis Problems listening to these files? See media help. The Spotted Predatory Katydid (Chlorobalius leucoviridis) is an acoustic aggressive mimic of cicadas. The listrosceline katydid Chlorobalius leucoviridis of inland Australia is capable of attracting male cicadas of the Tribe Cicadettini by imitating the species-specific reply clicks of sexually receptive female cicadas. This example of acoustic aggressive mimicry is similar to the Photuris firefly case in that the predator's mimicry is remarkably versatile playback experiments show that C. leucoviridis is able to attract males of many cicada species, including Cicadettine cicadas from other continents, even though cicada mating signals are species-specific.[49] Some carnivorous plants may also be able to increase their rate of capture through mimicry.[50] Two Bluestreak cleaner wrasse cleaning a Potato grouper, Epinephelus tukula Luring is not a necessary condition however, as the predator will still have a significant advantage by simply not being identified as such. They may resemble a mutualistic symbiont or a species of little relevance to the prey. A case of the latter situation is a species of cleaner fish and its mimic, though in this example the model is greatly disadvantaged by the presence of the mimic. Cleaner fish are the allies of many other species, which allow them to eat their parasites and dead skin. Some allow the cleaner to venture inside their body to hunt these parasites. However, one species of cleaner, the Bluestreak cleaner wrasse (Labroides dimidiatus), is the unknowing model of a mimetic species, the Sabre-toothed blenny (Aspidontus taeniatus). This wrasse, shown to the right cleaning a grouper of the genus Epinephelus, resides in coral reefs in the Indian and the Pacific Oceans, and is recognized by other fishes who then allow it to clean them. Its imposter, a species of blenny, lives in the Indian Ocean and not only looks like it in terms of size and coloration, but even mimics the cleaner's 'dance'. Having fooled its prey into letting its guard down, it then bites it, tearing off a piece of its fin before fleeing the scene. Fish grazed upon in this fashion soon learn to distinguish mimic from model, but because the similarity is close between the two they become much more cautious of the model as well, such that both are affected. Due to victims' ability to discriminate between foe and helper, the blennies have evolved close similarity, right down to the regional level.[51] Another interesting example that does not involve any luring is the Zone-tailed Hawk, which resembles the Turkey Vulture. It flies amongst the vultures, suddenly breaking from the formation and ambushing its prey.[52] Here the hawk's presence is of no evident significance to the vultures, affecting them neither negatively or positively.