Translated material
"Here I am, here I am turning into an ant!"
Spiders are dangerous predators and at the same time the desired booty for birds, amphibians, reptiles and slower spiders. The spider is defenseless in front of the predator. That he can only run away or hide. Is it ants! In size, they do not exceed small spiders, while biting, spraying with ant and even help, if necessary, cause. Therefore, there are relatively few people who want to enjoy ants and many mimic under them. Among the imitators are about 200 species of spiders from the genus Myrmarachne family of Salticidae (spiders-sloping). These are daytime animals, free hunters.
The usual spider outwardly does not look like an ant. Mirmararane acquired an ant “figure” - an elongated body and a thin waist (Fig. 1). However, they have two typically spider signs that you can’t hide anywhere: eight legs instead of six ant and lack of antennas. Fortunately, the disadvantages of appearance are compensated by the correct behavior. You can go for an ant if you walk like him. After all, many of us distinguish friends from gait. It is possible that the predator reacts to this sign.
Mimicry of Spiders Myrmarachne has been studying the associate professor of New Zealand University Kenterbury Ksimen Nelson (Ximena J. Nelson). Together with her colleagues, she compared the quantitative characteristics of the movement of the four types of Mirmarakhn ( M. aurea, M. Lupata, M. Rubra, M. Smaragdina ) and ants, which apparently became an object for imitation, as well as five types of slide spiders that do not mimic (hereinafter for the shortness of “ordinary spiders”). Scientists analyzed the frequency of stops, the speed of turning and the manner of their implementation: in place or in movement [1]. It turned out that ants and Mirmararane when walking stop less often, and the turns are performed quickly on the go. Ordinary spiders are more often interrupted by running, turning more slowly, stop after turning. Then the researchers created a three -dimensional image of Mirmararane, which moved either in an ant manner, or as a regular spider. This cartoon was shown on the screen to the predatory spiders of the Sandalodes Bipenicillantus , which do not mimic and hunt other spiders. If the figure on the screen moved like an ant, the predator was not interested in her little, while he rushed at the image running with an ordinary spider trot. Therefore, you cannot deceive one antwain -like appearance. To achieve success, it is necessary to move like an ant.
The details of the Mirmararakhn gait were interested in the specialists of the University of Cornell (USA) under the leadership of Professor Ronald R. Hoy (Ronald R. Hoy). They worked with M. Formicaria spiders, the working ants of the genus Formica and representatives of three types of ordinary horses - Salticus Scenicus , Sitticus SP. and Phidippus audax [2]. First, scientists studied the gait of animals step by step, for which they photographed it on a video camera at a speed of more than a thousand frames per minute, and then looked at low speed. This method allows you to make out the details invisible to an ordinary eye.
It turned out that ordinary spiders are trot on their eight legs. Ants run to six, but when walking, they regularly lower the antennas, touching the earth with them. M. Formicaria walk on eight legs, shaking the abdomen, like ants, but sometimes they suddenly stop and raise the front legs, like antennas (Fig. 2). The stop lasts a tenth of a second, you can see it only with slow shooting, and it creates the illusion that we have a creature with six legs and a couple of antennas.
Will these tricks deceive a real predator? To do this, the researchers removed three cartoons on which the black silhouette of an ant, M. Formicaria or the usual spider-slide runs around the white field (side view), and showed them to the predatory spider P. Audax, a great lover of small arthroopol. If the spider believed that prey was running in front of him, then he tried to grab the image [3].
It rushed at 75% of ordinary spiders, but only 15–25% M. Formicaria and ants. Deceived.
Researchers note that many spiders walk on six legs, using the front pair as specialized antennomic structures. These are flagella frines ( Amblypygi ), burning telphones (Thelyphonida) and hayfields Opiliones. And even representatives of other detachments can cost six limbs if they lose a couple in a fight with a predator. Nevertheless, Mirmarakhran walks at eight. They could not switch to six -time, did not have time or did not consider it necessary, because their gait already misleads the predators? This is yet to be found out by scientists.
You have to pay for any acquisition. For their resemblance to the ants of Mirmarakhran, they paid the loss of abilities that facilitate the hunt. During the experiment, the researchers have never seen Mirmarakhran jump. Apparently, they really forgot how to do it. They do not rush to prey from afar, like other horses, and are forced to grab it, creeping almost closely. And it’s easier to look for the victim, moving in a straight line, and not writing out the sinusoid. In addition, absolute protection does not exist. There are many predators who successfully go to the ants, and the spiders that imitate the ants also fall into the circle of their attention. It is possible that birds with their sharp vision are not amenable to the deception of mimicry - this also has to be checked. But the advantages provided by mimicry obviously outweigh all the inconvenience.
While the spiders spent so much effort to become like the ants, there are insects that strive to resemble spiders-scacuers [4]. This is a moth Brenthia coronigera, which, when sits, takes a spider pose: lifts the front wings, and turns the rear, showing the spots similar to the eyes of the spider, and the strips resembling spider legs (Fig. 3). Moving along the flower, it bounces like a spider-slide. Not only a person, but also predatory spiders manage to deceive these butterflies in spider skin. The skin, by the way, is extremely important. If you erase the spots from her, eat, and no jumps will help.
Natalia Reznik
1. Nelson XJ, Card A. Locomotory Mimicry in Ant-Like Spiders // Behav. ECOL., 2016, 27, 700–707, DOI: 10.1093/beheco/ARV218.
2. Shamble PS, Hoy RR, COHEN I., Beatus T. Walking Like An Ant: A Quantitate and Experimental Approach to Understanding Locomotor Mimping Spider Myrmarachne Formicaria // Proc. R. SOC. B, 2017, 284: 20170308, DOI: 10.1098/RSPB 2017.0308.
4. Wang My., Vasas V., Chittka L., Yen SH. Sheep in Wolf's Clothing: Multicomponent Traits Enhance the Success of Mimicry in Spider-Mimicking Moths // Animal. Behavior., 2017, 127, 219–224, DOI: 10.1016/J.ANBEHAV.2017.03.020.