May 3, 2014 | 5
This is my second post in a week featuring spiders doing undeniably adorable things – dancing and cartwheels. It’s as if spiders know they have a reputation problem and have launched some kind of secret PR campaign to highlight their cuter, less-likely-to-give-you-skin-rot members. But then a bunch of ‘yellow sac spiders’ (cuteness diminishing) invaded a Mazda factory in the States, forcing the company to recall 40,000 cars (cuteness diminished). When a Mazda spokesman was asked by the New York Times why he thought the spiders were so attracted to the cars, he said, “Don’t ask me, I’m terrified of the damn things.” Right on, Spokesman. I hear you.
If only jumping spiders could invade cars in plague proportions instead. They’re so loveable. It’d almost be a selling point to have those big, puppy dog eyes looking up at you from the dashboard. And if peacock jumping spiders got involved, it’d probably be the one thing that convinces me to get my license.
And now new species of peacock jumping spider has been discovered in Western Australia. Named Maratus pardus, the species is just 4.5 mm long, and belongs to the only genus of spiders in the world known to have flexible abdomen flaps that can be raised right up behind their heads. Decorated with incredibly bright and varied colour patterns in the males, these appendages are unique to each species, and play a crucial role in their elaborate courtship displays.
The male M. pardus’s colour pattern features a background of light blue or blue-green iridescent scales with an arrangement of 14 to 18 spots of red-orange or orange scales in the centre. These spots are flanked by a series of light yellow scales that form distinct borders along the sides of the abdomen flap.
Spotted by David Knowles, who runs a company in Perth, Western Australia that educates the public about invertebrates and biosurvey called Spineless Wonders, 20 years ago, the species has been formally described in the journal Peckhamia by Sydney-based biologist Jurgen Otto and the journal’s editor, David Hill. The unique spotty pattern on the male’s abdomen flap, plus its slinky, cat-like movements, prompted the pair to name it after the leopard – ‘pardus’ comes from the Ancient Greek word for ‘leopard’.
“It is the only species with such distinct spots on the back, and therefore can be easily distinguished from other peacock spiders, quite beautiful I think,” says Otto. “The cat-like behaviour is not unique to this species, and in fact is shared by all jumping spiders. They very slowly approach their prey and then pounce on them.”
Having examined 30 specimens, including males, females, and juveniles, Otto and Hill have identified the equally beautiful Maratus volans as the species’ closest relative. According to their records, M. pardus is now known from the subcoastal swamplands of Cape Le Grand National Park, about 630 km south-east of Perth, and from an unspecified area near Ravensthorpe, some 540 km south-east of Perth.
Like the other 27 known species of peacock spider – all of which are endemic to Australia – M. pardus males and females participate in an elaborate courtship ritual that involves the brightly coloured males showing off their abdomen flaps for an extended period of time as they raise their legs in the air and move around the female. The whole time, they never take their eyes off their potential mate, on the one hand to show their commitment, on the other to watch for signs of an attack. Like many spiders, female peacock spiders are quite happy to attack an unwanted suitor if she’s feeling harassed.
“Obviously you have to get a female to make the male display,” says Otto of the filming process, “but when a female is introduced and the male becomes aware of her presence, the response of the male is quite quick. Then it depends on the female’s reactions what happens next. In most instances, the females I find are already gravid [pregnant] and they do not want to mate. So, as I have shown in the video, they will either escape from the male, attack him, or they lift up their opisthosoma [posterior] and walk away from him. Sometimes the males still keep pursuing them (god knows why), [but] sometimes they get the message.”
Peacock spiders might be the only spiders in the world to wield expandable abdomen flaps, but that doesn’t stop the rest of the jumping spider family (Salticidae) from participating in their own complex courtship rituals. Researchers from the Elias Lab at the University of California, Berkeley have been investigating the courtship dance of a species of North American jumping spider in the genus Habronattus, the males of which emit a noise that sounds just like a revving motorbike to attract the females.
“All peacock spiders produce sound during their display, and the visual part is only one component, but we are unable to hear it,” says Otto. “Species in the genus Saitis also lift up their third pair of legs during courtship, but they lack flaps. Obviously with the big eyes that jumping spiders in general have, courtship is a lot more visual than perhaps in other spiders that rely more on touch.”
If a male’s courtship dance is well received and a pair successfully mates, the female will lay a clutch of 5 to 13 eggs inside a silken sac, where they will be incubated for two weeks. It takes another two weeks for the hatched young to develop and grow inside the egg sac, and their mother will stay to protect them, neither of them eating or drinking anything at all. After this, the young will molt and leave the egg sac, growing to adulthood in the course of several months.
Having collected a number of adult male and female M. pardus individuals from Cape Le Grand, Otto managed to raise a number of juveniles too. You can see the size difference in this image:
They might look like a happy family, but all is not what it seems. “I have made them jump onto the same stick and then quickly got a picture,” says Otto. “They would not usually sit that close together and it was not easy to get them sit still for very long. I only did that so I could capture them in one picture and show the size difference. In fact, they are probably at risk to be eaten by their mother, but whether that happens I don’t know. You will find a picture [on my Flickr site] where mom Maratus sp. 3 pounced on the young. At first I thought the young is gone, but after what seemed like a couple of seconds she released him/her. I was very surprised by that. Obviously something told her that she should not eat it.”
Otto has recorded a bunch of incredible peacock spider courtship displays, and they’re all available on his YouTube channel. His Flickr gallery is also well worth a visit, and features several as yet undescribed species of peacock spider.