Understanding Spiders

When it comes to attracting a mate it can sometimes seem like an uphill struggle for a lot of species. And for a lot of ecologist it can rapidly become a life time’s worth of work understanding all the subtle cues and hints that animals send each other. Understanding an animal’s courtship can sometimes be the difference of survival or extinction, if humans are ever needed to intervene in a captive breeding programme and don’t understand certain things that an animal needs, well you get the issues that we have had with breeding the Panda bear, we have only just recently learned of improved mating when given a choice of partners.

Unlike Panda’s, spider’s sex lives are, for the most part, not headline news. However with being put under increasing threat of extinction and the valuable role they play in the world’s ecosystem it wouldn’t hurt to know basic reproductive information about them. This paired with most spiders, if females rebut the male’s forwardness it usually ends with a good meal for her, and a researcher wondering what happened in the courtship attempt to lead to this. A trio of researchers, 2 from the university of California and 1 from the New South Wales University have found with Peacock spiders prefer a multi-modal courtship from their potential mates.

MalePeacockSpider Jurgen Otto

Male Australia peacock spider Maratus volans, courtship display.

In their paper the Female preference for multi-modal courtship: multiple signals are important for male mating success in peacock spiders. published in the Proceedings of the Royal Society B, Madeline Girad, Damin Elias and Micheal Kasumovic looked into the peacock jumping spider Maratus volans,  courtship preferences and how this may have lead to the extreme levels of ornamentation you find on male peacock spiders.

Scientists have known for a while that males have used in ornamentation, such as colourations, and appendages, in the past to attract females, as well as what we would consider ‘dances’.  Until now it has not been clear is how the females choose between the suitors or if it is sole judged on the visual or tactile display of the animal. And with Maratus volans being such a visual based animal it was always assumed it was solely based on the visual display that the male showed.

Jumping_spider_vision_David_Hill

Visual field of a jumping spider, David Hill.

 

Maratus volans has a high level of ornamentation and it has been known to scientist for a while that they have used this to attract females. Males possess a large and colourful ‘tail’ that is able to expand and spread like a peacock, they also have colouration on their legs. These colourations paired with a unique vibration based dance, unique as it differs between members of the same species, are what the male spiders use to impress the female.

With 64 male/female pairs put in ‘courtship arenas’ where they were able to engage in courting whilst being filmed, the aim to see if it was possible to figure out how each female decided whether to mate with the partner or not. It must be said that in the experiment that the females were not often impressed with what the males had to offer, with some females simply turning away to simply eating the offending party.

Overall the scientists found that the females liked only 16 of the courtship dances, but by comparing the success rates, they were able to determine that the average was, the way the male looked was twice as important as how he danced. Despite finding this out they concluded that sexual selection ultimately came down to the combination of both the visual and vibratory displays that the males performed.

 

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A Behavioral entomologist. I love the little things that are often overlooked.

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