Salticidae: Jumping spiders

Salticidae is the largest spider family of the world, and easily the most charismatic. Their large frontal eyes and visually driven behaviour makes them instantly likeable. They are mostly diurnal and have a preference for sunny, warm habitats, which means it is not so well represented in the UK. There are just 36 species, most of them in the south and many very locally distributed. Jumping spiders are also easily recognisable for their eye pattern: four eyes facing forward, the central two much larger than the others. Jumping spiders move in a distinctive way, with sudden runs forward and frequent stops, when they orient their cephalothorax ostensibly to look around. They jump very well, and do to do so in a controlled way (unlike grasshoppers and fleas, which can jump longer distances), always securing a drag line just before each jump. Silk is used as safety lines and also to weave a sac for resting.

Visual spiders
Jumping spiders are the arthropods with the best visual sense. Their large anteromedian eyes are responsible for their visual acuity, while the remaining six eyes act as motion detectors. The lens of the eye is part of the cuticle and is fixed, but the eye tube orientation is controlled by six pairs of muscles. They have an additional internal lens in their eyes, which together with the detailed configuration of the retina makes them work like miniature telephoto lenses. Their acute visual sense is used during hunting, to locate prey often at remarkable distances. They can approach prey taking a detour, instead that on a straight line, and when they are close to the prey they stalk it before jumping on it. They can also use a sit-and-wait strategy, constantly scanning the environment visually.

A male Salticus scenicus with a house fly prey.

Female Salticus scenicus with prey, probably an aphid.

Semaphore courtship
Salticids have colour vision, even in the ultraviolet. This explains why some species are so strikingly colourful - often with iridescent scales or cuticle. Males have often more colourful palps, front legs, chelicers and the area around the eyes, and these features are used during courtship. They use a combination of visual and auditory cues (drumming) during courtship, which can incude chelicer opening, abdomen drumming and palp waving, often in a mesmerising, balletic routine, which the females watch attentively. I really recommend watching the fantastic collection of videos of the Australian Peacock spiders by Jurgen Otto, which have taken spider courtship to its most dazzling extremes. The stripped black and white Salticus scenicus or Zebra Spider, is widespread in the UK. In this species the most obvious difference between males and females is the size of the chelicers, which are massive in the males, and are used for sparring (watch this short clip of two males sizing each other up), but their courtship is not the most complex. The males raise their front legs and open and close the chelicers in front of the female, but they also chase females into their retreats, where mating often happens.

Male Salticus scenicus. Note the long black chelicers with the palps over them (look at the female on the top shot for comparison).

Synanthropic species
The tiny Pseudeuophrys lanigera seems to have a preference for buildings and roofs. I have found it inside my office and lab a few times, and once on my house wall. It is probably very under-recorded due to its small size (5 mm).   

 

Female Pseudeuophrys lanigera.

Pseudeuophrys lanigera, note the white palps and moustache, red markings around its eyes and dark shiny front legs

Another human-associated salticid in the UK is Hasanius adansoni. A tropical species in origin that has expanded across the world to occupy buildings in warmer areas or heated glasshouses in cooler climes. In the UK, there are records from the early 1900s, and it has been found in Kew Gardens, the Eden Project, and the Royal Botanical Garden at Edinburgh, amongst other places. In Edinburgh, it is likely there has been a colony for over a hundred years. The following photos were taken in a garden in Mallorca. Males and females are strikingly different, the male is darker with white stripes at the front of the abdomen and palps. red 'goggles' and black front legs. The female is very pale, with a yellow face.

Male Hasarius adansoni.

Female Hasarius adansoni.

Ant mimicry
Three genera are very convincing ant mimics, moving and looking like ants. Myrmarachne has a raised front of the cephalothorax, which gives an impression of the ant's head. Some have constrictions in the abdomen and the colour patterns further disguise the presence of eight legs. The ant mimics are quite scarce and local here where they reach the limits of their distribution, but are much more numerous in the tropics.

Fearsome stripy jumper

Given the current rainy weather, I was pleasantly surprised to find this male Zebra Spider, Salticus scenicus, on my conservatory wall, inside. Zebra spiders have a bare black body, with white scales and some brown scales on the abdomen. They are warmth-lovers, coming out of their hiding places on clear days, often on walls after they have been heated by the sun. Salticus males have huge chelicerae for their size (a tiny 5 mm!), and they can be seen moving their palps over their black chelicerae as they move about. The chelicerae are opened in a display to rival males, and, if the contest escalates both males will face each other and lock their opened chelicerae together in a sparring match, as shown on this video in Arkive featuring a fight:

A top view of the male Salticus scenicus

Another male showing more brown (photo 20/04/11). The angle allows to see the long fangs folded underneath. Relative to its size, I think they are longer than in Dysdera.

 Despite their tiny size, Salticus make fearsome hunters. A few years back I surprised this male with a fly larger than him.

Male Salticus scenicus with fly (13/05/2009)

Female on 30/04/2011

Do you recognise this female? She is featured in the Bugblog banner. You can see her smaller chelicerae and white palps. Often females have beautifully marked black and white abdomens which give this spider its English name.

Office jumping spider

I watched this tiny jumping spider this morning crawling up my office wall. It must have been 4 mm in size. It carried its dark front pair of legs pointing forward, which gave it a crab like appearance, but its lovely face with large, front facing middle pair of eyes were unmistakable as a jumping spider. It was a male Pseudeuophrys lanigera, a synanthropic species, that is, often found in or around houses.
 The species originates from Southern Europe, and has spread throughout Europe during the last century. In the UK is also expanding north.
 Males have a striking combination of a red face mask, a white moustache, white palps, and robust, black front legs, females are a bit more subdued, and their front pair of legs is annulated as the others.

the male on top view

female (9/04/11)

same female on windowsill (9/04/11)

Hey, baby!

 Under the holly, on the leaf litter, wolf spiders (possibly Pardosa amentata) bask in the sun. Most females carry bulging egg sacs under their abdomens, while trying to find the best position to get warm. Several males move about, approaching a female with tentative steps, then tiptoeing, vibrating their front legs and black palps, and moving his palps alternating one up, the other down, as soon as he is very close (photo above).

The male from the top photo, gets a bit closer. This female is carrying an egg sac and snaps at him. 

He quickly retreats and starts stalking the next female... 

This one does not have an egg sac. Will he be lucky this time?

No, rejected again. A short moment of rest with the male and two females basking nearby

A female with a very large egg sac. The spiderlings must be close to emerge.

UPDATE 6/12/11: a little video taken on the day of one of the courting males:

Fascinating jumping spiders

We had a very warm day today - for April - the sun hit the brick walls and this is something that brings jumping spiders out. I spot one on the wall, quite high up, she moves in a typical jerkily fashion on to a wooden plank and I take a few shots with my arms outstretched and a poor view of the LCD display, but I am happy when manage a few focused front shots (above). I think this is Salticus cingulatus, a close relative of the zebra jumping spider, Salticus scenicus. Jumping spiders, or salticidae - the family latin name - are the largest spider family, with 5,000 species. They have a highly acute visual sense, with their large and forward facing antero-median being responsible for the visual acuity, and the remaining 6 eyes - with the posterior pair facing almost backwards - acting as motion detectors. Although the external lenses are fixed, the internal eye tube can move to precisely look towards an object. Some species have been shown to have colour and UV vision (tetrachromatic vision) and correspondingly, jumping spiders include some of the most colourful spiders. Their mating rituals are mesmerising: they include synchronic front leg movements, abdomen vibrations and percussion, yes, percussion! They remind me of flamenco dancers with their tap shoes and castanets. Something that cannot be imagined and have to be seen:


I often come across feeding jumping spiders. Then they are preoccupied and they are much easier to approach. This male S. scenicus had caught a fly and came to inspect me, before returning to its oversized prey.

The following one, a tiny, possibly immature specimen still poorly marked, was preying on an aphid in my conservatory bougainvillea.

Jumping spider are extremely agile and their hunting has been compared to a cat stalking its prey. First the spider moves its "head" fixing its eyes on the potential prey, then the abdomen is aligned and then the spider moves slowly towards prey. When the prey is within jumping distance, the spider ties a line of silk to the substrate and pounces on the prey. Surprisingly, jumping spiders can detour when jumping, and approach does not need to be in a straight line, with the spider losing sight of prey in occasions, suggesting remarkable planning for a tiny invertebrate. Salticids show a range of predatory strategies from extreme sit-and-wait species which only move to jump into passing prey to specialist ant predators, to cleptoparasitic species, which specialise in robbing spider webs or deceptive prey-mimics, who imitate the movement of prey that has fallen on a web to lure the spider out and the eating the spiders themselves. There is even a herbivorous jumping spider, the just so named Bagheera kiplingii, from Mexico, which exploits an ant-acacia mutualism, mainly  feeding on specialised leaf tips produced by the acacia for its mutualistic ant, and nectar, complementing its diet with a few ant larvae. What amazing animals they are.

References
Richman, David B., & Jackson, Robert R. (1992). A review of the ethology of jumping spiders Bulletin of the British Arachnological Society, 9 (2), 33-37

Meehan CJ, Olson EJ, Reudink MW, Kyser TK, & Curry RL (2009). Herbivory in a spider through exploitation of an ant-plant mutualism. Current biology : CB, 19 (19) PMID: 19825348