Showing posts with label Salticidae. Show all posts
Showing posts with label Salticidae. Show all posts

Wednesday, June 11, 2014

"If you wish to live and thrive, let a spider run alive."

The origin of this saying is a bit of a mystery. Is it an Old English nursery rhyme? An American Quaker saying? At least it contains more than a grain of truth (where would the world's ecosystems – and we – be without spiders?), and it's certainly better than the bit of folk nonsense – "Step on a spider and it will rain." One thing for sure, there are plenty of spiders running alive – in the grass, on leaves, on trees, under stones and on the water – almost anywhere you care to look.

The wonder is that spiders aren't noticed more often. True, some have lifestyles that require cryptic colors but many arachnids literally glitter and shine and are as dazzling as any butterfly or flower. Like this female Tutelina similis, for example. The photos simply cannot do justice to this spider, it's body, a whole 5 mm in length, is iridescent but the cephalothorax under the right lighting is a shimmering lilac color. Tutelina similis differs from the closely related Tutelina elegans in not having a white band around the abdomen.



Two tiny male spiders, about 3 mm in length, were in the vicinity of the female. Sure enough there was a connection – they were indeed male Tutelina similis (a male Tutelina elegans would sport black tufts of hair on its first tibia) and no doubt prospective suitors for her hand in marriage, metaphorically speaking, all eight of them ... and him with only seven ...



A male Habronattus decorus ... the name is certainly apropos, how does irridescent pearl grey and glittering rose sound for a color scheme? Again, the image doesn't convey how striking this spider is in reality . All of this is packed into a mere 5 mm ... yes, Jumping Spiders definitely take first prize for appearance and color.


Doing its best to imitate a bit of dead plant debris or a dry seed, Acanthepeira spp makes up in funky form what it lacks in cool colors. This Orbweaver is only about 5 mm long making it very easy to overlook, which of course is the idea from a predator/prey point of view.



Much like the origin of the saying in the title of this post, the identity of this ant-mimicking male arachnid is a mystery ...


... as were, until recently, the names of the following two spiders. But today, whilst researching the enigmatic ant-mimick I identified this male by stumbling across it whilst searching for something else – it's a Two-banded Antmimic (Castianeira cingulata). "Stumbling across" is used in a figurative and not literal sense, the spider is only about 6 mm long.



This pretty girl with the yummy name of Candystripe Spider (Enoplognatha ovata) was also IDed by random find (of the same blog!) on the 'net. Too bad she prefers to hide out in the shadows instead of showing off her colors.




Beautifully patterned in black and white, Neriene radiata, the Filmy Dome Spider, also prefers shady places. It's a male (note the enlarged palps) and it looks like he's molted recently because there's an exuviae in his web (look near the bottom of the first photograph).



It's easy to dismiss spiders and think of them, if not with outright fear and revulsion, as drab and uninteresting creepy-crawlies beneath our notice. Hopefully these photographs and the images elsewhere in this blog have shattered that illusion and illustrated the diversity of color, form, and the fascinating lifestlyes of spiders. They've been "running alive" for a cool 300 million years, that's a lot of time to be sifted though the sieve of natural selection and find their place in the tangled web of life on earth, and it's an ongoing process ...

Thursday, May 15, 2014

Salticid Snapshots

Saltation – from Latin, saltus, meaning "leap", and since jumping spiders lack extensor muscles at their leg joints they accomplish their amazing leaps by suddenly increasing the blood pressure to their fourth pair of legs. The precision of their predatory pounces is guided by their large AME – Anterior Median Eyes – the acuity of which are ten times better than the huge compound eyes of a dragonfly.

This pretty little female spider goes by the name of Marpissa formosa. She was found on the doorframe of a car and had probably been hitchhiking there for the past hour, hanging on for dear life. The reflective paint made a poor background, as did some red granite, but she obligingly jumped up and posed on my hand.




Male spiders are often much smaller than females; that's not the case here, both sexes were about 10 mm give or take. But they certainly are colored and patterned differently, and without a field guide or seeing a mating pair of spiders one would never guess that the male Marpissa formosa in the next two pictures is the same species as the female above.




Phidippus princeps (from Latin, meaning "first, chief, sovereign") is also roughly 10 mm long but much more robust. The salticid habit of always turning to face danger with those AME makes it difficult to acquire shots from different angles. In this case it presents this male's field marks quite nicely – white scaling on the palps, white fringes on the legs and blue-green chelicerae. The abdomen can vary between individuals and instars and isn't reliable for identifying this spider.

Like its cousin Phidippus audax a.k.a. the Bold Jumper this spider was totally fearless. He leaped at the camera, jumped on my hand (but of course didn't bite), and his last leap took him ... in my shoe? inside the leg of my pants? or he missed me and went into hiding? ... I'm not sure which.




A couple of Phidippus princeps females – again, there's not much difference in size between the sexes, but even so the females tend to be more robust than males. A good rule of thumb for sexing arthropods in general is "Eggs are bigger than sperm." In addition the males carry their sperm packets in specially modified pedipalps, the profile of which is unique to each species. The palps of females are unmodified, bristly and resemble short legs.



Phidippus princeps is as big as our local jumping spiders get, but the Regal Jumper (Phidippus regius) can attain a length of about 20 mm – large enough to tackle more than the standard menu of insects and other arthropods.


At the other extreme in terms of size is the diminutive Peppered Jumper (Pelegrina galathea). Attaining a length of only about 3 mm this mating pair of spiders was at the limit of the camera's macro.



The pair separated amicably after mating. The female fled the scene immediately but the male hung around for a minute and I was able to get a few photos for future reference.





A male Eris militaris a.k.a. Bronze Lake Jumper looks superficially similar to male Peppered Jumper, but it lacks the strong annulations on the legs, the branched white markings on the cephalothorax and the spots near the tip of the abdomen. In addition the Bronze Lake Jumper is about twice the length of the Peppered Jumper.


The vision of this small arthropod is amazing in proportion to its size. The male recognized a female of his species from a good 30 cm away and started signaling to her by wagging his abdomen and waving his modified front legs, making her aware of his intentions from a relatively safe distance. A necessary prelude to mating, because with their hair-trigger killer instincts jumping spiders will tackle anything that moves and looks small enough to overpower and eat.


The female is a few millimeters longer than the male and much heftier. She did have dinner on her mind, albeit a midge rather than her prospective mate, wasn't receptive to his advances, and no mating took place. So although the markings are correct for an Eris militaris female there are other jumper look-alikes and it's not possible to conclusively say these two spiders were the same species.




The attractive spider in the next group of photos is a female Dimorphic Jumper (Maevia inclemens), she's about 8 mm long.



This looked like a dramatic opportunity to acquire a dramatic shot of the spider catching dinner but it turned out to be something better. The spider homed in on the ant and started to leap but then aborted it, and when I looked at the image on the computer screen I saw why. It looks like the ant was threatening to (or maybe did) spray formic acid or some other nsty chemical at the spider.


Male Dimorphic Jumpers are two to three millimeters smaller than the females. Its small size combined with cryptic markings made this one almost impossible to see against the background of lichen encrusted stone. The males come in two color forms, here's an image of the other variation at BugGuide.Net.



Always look twice – I jumped to the conclusion that these itsy-bisty mottled brown spiders, only about 3 mm in length, were the immature instars of a species I was already familiar with, perhaps Salticus scenicus.


Not so ... one of the spiders became agitated at my presence and waved its palps around, whereupon it became obvious that this was a fully mature male.


Sometimes immigrant species die out because conditions simply aren't right for them in their new habitat. They may – like the ubiquitous primate Homo sapiens – find themselves in an favorable environment with a plentitude of food and lacking the limiting factor of predation, overpopulate their habitat and outcompete the native species, in which case they get bad press and have epithets like "invasive" hurled at them. Or, like the Asian Jumping Spider (Sitticus fasciger), they can blend into the background, fit right in, and live their little lives, doing what spiders do best ...



"If it is not small enough to eat nor large enough to eat you, and doesn't put up a squawk about it, mate with it." ~ (David L. Jameson, Systematic Zoology, 1955) ... that pretty much sums up the lifestyle of jumping spiders, and the rest of nature as well.

Saturday, August 21, 2010

Spider Snapshots

Several species of jumping spiders (family Salticidae) are extant in our area. The spider in the following four images is a female Bold Jumper (Phidippus audax), about 15 to 20 mm long. The three white (less frequently red, or orange as in this specimen) spots on the abdomen and iridescent blue-green chelicerae are typical field marks. Juveniles often sport orange spots.

Bold Jumpers come by their name honestly as they have been known to leap at photographers who have approached too closely. This spider was obviously feeling threatened by my presence.


There isn't enough detail in the next two images to determine if this is Eris flava or Eris militaris. For anyone interested here's a link to more information at BugGuide.Net. (EDIT: one year later, and lot more research ... I now believe this jumper is more likely genus Pelegrina).

I'm not sure as to the identity of the less vividly marked jumping spider in the next two images.


No collection of jumping spider images would be complete without the including photos of the ubiquitous Zebra Jumper (Salticus scenicus).


Sparking up the color scheme a bit: a female Black and Yellow Garden Spider (Argiope aurantiae) that has nabbed a paper wasp.

The following image is out of focus because the spider is shaking its web, and by no small amount, the spider was displaced by about two inches. I've observed this reaction in other orb weavers if they are approached too closely for their comfort. Is the purpose of this to make the spider a more difficult target for a potential predator?


Six-spotted Fishing Spiders (Dolomedes triton) are common along the north shore of Stoco Lake. The female in the image below is about 20 mm long. In the complex tangled web of life even large predators are not invulnerable; a smaller immature spider of this species has been captured by the Blue Black Spider Wasp (Anoplius sp.) in Life's a Beach.

As a rule Fishing Spiders are found on the shoreline or floating water plants. This is the first time I've seen one was making a web in the vegetation a few feet off the ground. The spider assumed this posture whenever I brought the camera up close.


Many species of Hymenoptera are parasites of spiders, but when I turned over a stepping stone in the garden I chanced across a scene where the tables were turned and found a Wolf Spider (Lycosa sp.) with an unlucky ant in its grasp.


Gardens host a variety of spider species; the spiders are attracted to the insects nectaring on the flowers. A Ground Crab Spider, probably Xysticus sp., assumes its characteristic ambush pose on an iris leaf.