A few of the Common at BLP

The following notes are specific to BLP, but also be useful throughout coastal California. The best beginning book on spiders is Spiders and their kin by a Harvard professor and his wife, Herbert and Lorna Levi. The book is in the library and is available at the bookstore. The notes below often refer to that book by page number. These notes were slightly rewritten by Greg de Nevers from an earlier version by Mary Anne Saddler and Ann Christensen. They were further slightly modified by David Herlocker and subsequently modified by Gwen Heistand.

GENERALITIES. Male spiders are generally smaller than females, and often more cryptic. Females have bigger (full of ). Mature males have a pair of enlarged palps that look like boxing gloves in front of their face, females never do. Virtually every web you see has a spider on or near it. Look for them! They often hide where a radial strut attaches to a near the top of the web. There are no records (specimens) of brown recluse spiders from the Bay Area.

ORB WEAVERS. Orb weavers (a – Araneidae – with many genera) are the classic spiders, like Charlotte, making a wagon-wheel shaped web. They are the most numerous and diverse group of spiders. With a life span of one or less, they emerge from their sacs in spring as tiny spiderlings. They balloon away from their birthplace, grow through the summer, and lay eggs in the fall. Orb weavers are the only spiders known to write in English. There are many small, fascinating orb weavers at BLP. A few large, glamorous ones are described here.

Garden Spiders ( , pg. 68). There are two common garden spiders at ACR, the banded garden spider, (=silver garden spider, = ), and the golden garden spider (= yellow and black garden spider, = ). Garden spiders hang -down in the center of their orb webs, which have a vertical zigzag of extra woven in (the stabilimentum). The stabilimentum got its name from the theory that it provided extra support for the web. Now it’s thought that the range of light it reflects may attract (prey). Spend a little time looking at the web, and you can see that it is not precisely vertical, rather slightly tilted from vertical. This is so that when the spider drops, she can drop straight down and not get tangled in her own web. When a victim is caught in the web she speedily wraps it in silk and then inserts her fangs to kill it.

The males are smaller, and can be seen in webs of their own, or on the outskirts of the female’s web. The male courts the female by plucking web strands in specific patterns. Essentially, he plays her a tactile “tune.” As many as seven males have been seen simultaneously in the web of one female. Many of us have learned that females kill and eat their mates once transfer is complete. It turns out there’s something a little more dramatic going on in the sex life of our beloved yellow and black garden spider, Argiope aurantica. During spider sex male spiders insert sperm into the females using their sequentially, one after the other. When the male A. aurantica uses his second palp, he “suffers irreversible seizure,” becoming completely motionless, his heart stopping altogether within 15 minutes. “The dead male’s inflated palp remains wedged inside the female. This prevents her from again, and gives his sperm crucial minutes to fertilize her eggs. The female cannot pull the male out for at least 15-25 minutes. Other males try hard to pull the dead male out, but often fail.” So he is turning himself into a copulatory plug or as the article says a living-soon-to-be- dead “chastity belt.” Pretty wild! The female will eventually eat her mate; however she is not responsible for his death.

1 This sliver banded garden spider (A. trifasciata) makes an egg case that has a flat top. The top when viewed from above often looks like a piece of leaf caught in the vegetation. The yellow and black garden Banded Garden Spider spider (A. aurantia) constructs a pear-shaped egg sac that turns a wonderful brown as it ages. Golden Garden Spider

The construction of the egg case is really an amazing feat. Argiope aurantia constructs her egg sac while hanging downwards from her web. She lays a series of cross lines attached at several points to create a scaffold. Then she lays down yellowish threads to form a rectangular roof, and on this she spins a thick tuft of fluffy yellowish silk. Into this “feather bed” she spins a firmer sheet of dark brown silk and she lays her eggs upwards against this brown silk. The egg mass looks like a hanging yellow spherical ball. A. aurantia then spins a thin, tough covering that joins the brown silk disk. Around the whole mass (eggs, their covering, and the rectangular roof) she spins a fluffy covering, and over this padding a finer covering of silk that eventually dries, hardens, and turns a brownish . (To summarize: 6 different sheets, tufts or covers, making three envelopes!).

Pumpkin Spider or Shamrock Spider (genus , pg. 57). Araneus is a large genus of often-colorful spiders, which make a retreat off of the orb itself. The pumpkin spider (Araneus trifolium) builds a retreat off of the orb, a cup-shaped structure, opening down. She uses a separate radial line as a signal line, through which she can feel the vibrations of moving prey. Pumpkin spiders are usually orange, with white lines or bands on the legs. (Interestingly enough, the same on the east coast is greenish and often referred to as the shamrock spider. We occasionally find greenish ones her as well.) In late fall she lays her eggs in a case of fluffy, white silk which darkens as it ages. There can be as many as 2,000 eggs in a single case.

Debris spider (genus , pg. 63). Cyclosa is an orb weaver who makes a very finely meshed web. She sits in the center, but is wonderfully camouflaged in a vertical line of debris she weaves into the web. The debris consists of plant material, as well as dry prey items. (This debris line is also referred to as a stabilimentum.) The of our most common debris spider is distinctive, being conical leading to its name, Cyclosa conicum. (There are four species of Cyclosa in the Bay Area.) When she is ready to lay eggs they are added to the line of debris, much like the labyrinth spider below.

Labyrinth Spider or Condo Spider (genus , pg. 64). The labyrinth spider is one of the most prominent orb weavers at BLP. The webs of different individuals are often built in close proximity, even sharing support strands. Could these spiders be called semi-colonial? Large Ceanothus bushes may have as many as twenty labyrinth webs, each branch opening supporting one or more spiders. The web is distinctive, consisting of a typical orb, plus a tangle of irregular, dry strands above or to the side of the orb. The spider sits hidden in a retreat in the center of the tangle, with a line to the orb hub to sense prey. The retreat is usually made of a leaf rolled conically, open end down. The spider will shake the web to make her prey move in to locate it. Condo spiders enclose their eggs in a sac that has the shape of a double convex lens (lenticular egg sacs). The first egg sac is formed near the entrance of the retreat and the others are placed successively in a 2 line below the first one and fastened to a strong cord of silk. There are usually 5-6 cocoons with about 30 eggs in each. The cord supporting the egg sac is stretched between two branches and is strengthened with additional draglines. The egg sacs can survive winter storms and will be held securely in place after all traces of the web have disappeared. (Although, some accounts say that the young spider hatchlings use the messy web portion as a nursery.)

Long-jawed Spider, or Stream Spider, or Marsh Spider (genus , pg. 71). The most prominent spider in marshy areas, and around the edges of ponds and streams is the long- jawed spider. She sits with six legs extended parallel to her body, often on a grass blade or reed. She holds on with her short third pair of legs, and blends into the vegetation. Her web is often horizontal or close to it, rather than the typical near-vertical orientation and is missing the central hub. The male has special spurs on his . When courting, the male and female approach each other with jaws agape. Their front legs come in contact with each other and male pushes female’s legs apart and employs the special spurs on his jaws to lock into opposing spurs in her jaws … keeping her jaws out of commission and facilitating non-fatal sperm transfer. The trouble often comes when he leaps backwards to safety. This leap is not always successful.

Zygiella (genus , pg. 61). Zygiella webs are distinctive not for what they have, but for what they lack. The spider omits the spiral, sticky threads from one or two inter-strut as she weaves her web, giving the impression of a pie with a slice or two eaten. The strut through this section is the signal line to the spider in her retreat. During mating the male plucks the signal line to attract the female out of her retreat. This spider is not native to North American, but to Europe.

All of the above mentioned spiders are members of the family Araneidae, the orb weavers. The following spiders are representative of some of the diversity of spiders in the world.

Badumna (). The spider making messy webs on the sides of all the buildings at BLP is an introduced spider from Australia, . The Desidae is a family of cribellate silk spinners, so the webbing looks smoky and grey. The web is like an orb, but less organized and with large, loopy mesh. The messy webs of Badmuna have almost a lattice-like quality.

3 Triangle Spider (Family , genus , pg. 115). The triangle spider makes a distinctive web, of which she is a part. It consists of only a few segments of web forming a triangle (4 rays and 10 or more lines). The spider attaches a thread to some solid object and a tension thread to the apex of the web. She is a living part of her web! When she feels prey she releases the tension thread and the web collapses on the prey, ensnaring it. (Other accounts say that she will take up slack in the tension web, pulling it taught. When the spider releases it, she never completely lets go. From what I have read, both of these things occur.) An additional point is that her web is sticky not by virtue of glue, as with most other spiders, but is composed of specialized, “hackled threads” (cribellate silk) which are sticky because of their structure. As if this were not enough, the triangle spider is a member of the only family of spiders known to lack glands. Look for triangle spiders in redwood trees under the heronry.

Sheetweb spiders, and Bowl-and-doily Spiders (Family Liniphiidae, pg. 46). On a foggy day everywhere you look in the grass and foliage are the platform webs of sheetweb spiders. These are simple, horizontal structures, often of two layers. The spider hangs upside down under the topmost layer awaiting prey, which she pulls through the web to capture. A variation on this theme is the bowl-and-doily spider ( pyramidalis), whose snare consists of a cuplike structure (concave up) above a sheetweb. The spider sits on the underside of the cup. Another spider, trigonum, is a kleptoparasite of bowl & doily spiders that feeds on their food – and occasionally on the spider itself. In the summer months, A. trigonum may inhabit up to 20% of bowl and doily webs, where it has caused death or departure by the host. Not as common at BLP, but very prominent at Bouverie is the , whose sheetweb is an inverted cup (concave down) with the spider underneath at the apex of the dome. The filmy dome spider is a riparian beast, and the further from the creek you go the fewer you see, and the smaller each individual is.

Funnel Web Spiders (Family , pg. 72). Funnel web spiders weave messy webs of dry (non- sticky) silk that contains a funnel on the margin. The funnel is open at both ends, allowing the spider to attack or retreat, and in which the spider awaits prey and eats them. The flat, horizontal layers of dry silk

4 don’t so much capture prey, as confuse them, allowing the agile funnel web spider to rush out and pounce. These webs have been used as canvases to paint on, and as band-aids to stop bleeding.

Comb-footed Spiders (Family ): Black Widow or Western Widow (Family Theridiidae, hesperus, pgs. 17 & 42). The only dangerously poisonous spider in northern California is perhaps the best known spider in our area, at least by reputation. The is rare at BLP, preferring dryer, hotter, interior climates. Bouverie would be a more likely place to seek them. Surprisingly, they are common under boards on Kent Island! The webs are remarkable, consisting of a tangle, with a number of vertical taught lines to the ground. Prey is snared when they bump the loosely attached taught lines and are whipped up into the tangle! Arachnologists refer to this type of web (an irregular tangle) as a cobweb. You will often find a spider that looks very much like the Western Widow that is actually a False Widow, ( grossa).

Another theridiid, that you are more likely to see, is the House Spider, or Domestic Spider (Achaeranea tepidariorum, pg. 40). She sits in the corners of your house (and the OVC) and eats the house you are studying. She spins many of the cobwebs you clean out. The house spider is often confused with the cellar spider (below). House spiders spin brownish, pear shaped egg cases, which they hang in their webs. They run or drop when threatened, rather than vibrating like the cellar spider.

Cellar Spider (family , phalangioides, pg. 33). Cellar spiders, along with house spiders (above) are the most common cobweb weavers in the corners of your house. They can be distinguished from house spiders by two behaviors: they carry their whitish egg cases in their jaws, and they do such rapid pushups when disturbed that they appear to vibrate in circles in their web.

Their webs mostly identify the previous spiders, more than their bodies. The following spiders are hunting spiders and do not make webs to capture prey! They do use silk for other reasons, however.

Wolf Spiders (Family Lycosidae, pg. 82). This is the most common and best known spider at BLP. One often sees them running in the grass, especially in moist areas and near ponds and streams. They run just as well on the surface film of water! This is the cheetah of the spider world, running down prey by speed, rather than stealth. Most spiders which do not spin webs to capture prey have well-developed eyes. Wolf spiders have four big eyes, which are easily seen in a captured individual. The females are commonly seen dragging their egg cases, which they attach to their . The egg cases, originally white, quickly become a dingy gray and look like a third body segment. The babies are incapable of opening the egg case, mom has to open it to release them. Later she carries her newly hatched offspring on her back, one of the few examples of maternal care among spiders.

5 Jumping spiders (Family Salticidae, pg. 98). If wolf spiders are the cheetahs of the spider world, jumping spiders are the leopards. With eyes so large they can resolve an image up to a foot away, jumping spiders stalk prey, then jump 10-20 times their body length to capture it! These are very hairy spiders, with multi-colored on all body parts. When cornered they turn to follow their tormentor visually, spinning in whatever direction is necessary. Males court females with complex visual displays, using the colorful front legs as flags. The front legs are also used to warn off other males, and one can elicit a wonderful show of aggressiveness from a male with a mirror. The female weaves a retreat in which she lays eggs, rests, and molts.

Crab Spiders (Family , pg. 94). Crab spiders are colorful, but not hairy spiders, which look and move like crabs. They scuttle sideways and backward in ways so reminiscent of crabs it is remarkable. They are often found hiding in or under flowers, which they often match in color, and where they ambush their prey. This group of spiders has taken cryptic coloration and to the max. There is a species that is the spitting image of poop – hence it’s name, the bird dung crab spider. The venom of crab spiders is so fast acting that and honeybees, upon which they commonly feed, are unable to sting before being subdued. In many crab spiders, the male is so much smaller than the female – he can crawl under her and mate without any danger. However, some male crab spiders wrap silk around the female’s head and legs and tie her to the surface to ensure a safe getaway after sperm transfer.

Mygalomorph Spiders: The following three spiders are primitive relicts of the spider of the dinosaur era. They are mygalomorphs, or members of the group that includes , turret spiders, trapdoor spiders, and bird-eating spiders. Mygalomorphs have fangs which open up and down. That is, they operate parallel to the midline of their body, not perpendicular to it as in all of the previous, advanced spiders whose jaws open sideways (perpendicular to the midline of the body). This group of spiders has 2 pairs of book which distinguishes it from all but one group of the “true spiders” or Araneomorphs. Mygalomorphs also have long, segmented, spinnerets, which trail out behind their body visibly. Their eyesight is not great and often relies on the male stroking and caressing the female. Mygalomorphs are long-lived (females 8-20 , males 3-7 years!).

Aggressive False . ( longitarsus, Family , pg. 24). This local “tarantula” is perhaps the biggest spider at ACR. It is seldom seen, but is responsible for most of the open on the road up Bourne Ridge. Unlike most burrowing mygalomorphs, Calisoga doesn’t line its with silk. The males wander in the fall looking for females and often end up in people’s 6 homes. The venom is potent (about like a sting, Greg tried it). The threat display consists of rearing up on its hind four legs, raising and spreading the front four, and baring the fangs. The display turns your stomach upside down. True tarantulas (Family Theriphosidae) are common in hot, dry areas of the East Bay, like Mt. Diablo, and Henry Coe State Park. Reports of tarantulas on Mt. Tamalpais refer to Calisoga. There are no records of “true” tarantulas from Marin County. American tarantulas defend themselves against predators by scratching off fine abdominal hairs which are hollow and venom filled and irritate the nasal linings of like coyotes, foxes, and skunks.

Turret Spider (Family Atypidae). This is perhaps the most loved spider at BLP, although few people have ever seen one. The turret spider lives in a burrow in the soil, which it extends vertically above ground by weaving a tube or chimney. The opening can generally be used as a collapsible collar. The turrets are stiffened silk connected to a long burrow. Douglas fir needles, dirt, leaves, and twigs are incorporated into the turret and act as triplines. The spider will sit at the edge at dusk awaiting victims. They can wait six months without eating, and may shed their skin to get smaller if need be! Males have one long process on their chelicerae to hold the females jaws open while mating. The turrets are best seen on the Harwell Nature Trail, Zumies Loop in the Doug fir forest, and on the Olive Hyde Trail on the slope of Volunteer Canyon.

Trap Door Spider (Family ? Genus?). For me trap door spiders (pg. 23) are the most charismatic of all. They are rare, difficult to find, and incredible to think about. They occur in small numbers on many of the mossy or clay banks (old road cuts) at BLP. Look for them on the Olive Hyde trail just south of Picher Canyon, on the mossy bank just south of the Clem Miller overlook, and in the forest along Zumie’s Loop and the Griffin trail. Until we dig one up and look at the animal we don’t know the identity of this beast! They have a comb-like rake of spines on the margins of their chelicerae that they use to dig. They waterproof their walls using saliva and earth and then apply a silken lining. As the spider grows, it enlarges it burrow. (Spider will lift trapdoor or gnaw thru and assault the spider in its burrow.) One of the most common trap door spiders in Coastal California is californicum, the California trapdoor spider: The cork shaped, thin doors of these spiders are camouflaged with dirt and leaves woven in, making the opening to the burrows difficult to see. Search for the "D" shaped outline of the burrow in a flat area along a road cut or in short grass. Better yet, take flashlight at night to areas where you have seen signs of them and you will sometimes find the open doors and protruding legs of the waiting spiders. The spider will usually fight to keep the burrow closed. Eggs and young are kept in the bottoms of the one inch diameter burrows and the young disperse during the fall rainy season, building burrows near the female's entrance.

Harvestman (Order , family Phalangiidae, pg. 132). Harvestmen are not spiders at all, but related . Harvestmen have eight legs, but only one body segment (unlike spiders, which have two). Harvestmen have no silk glands or spinnerets, hold their bodies close to the ground when moving, and have two minute eyes raised up on a turret, like a cyclops! They are omnivorous, and must drink nightly, often from dew. They are nocturnal, and often cluster in great numbers in the burrows of other animals during the day.

7 Spider of Common Spiders Mentioned Above:

Domain: Eukaryota Kingdom: Animalia Phylum: Arthropoda : (sometimes a subphylum) Subclass: Arachnida (sometimes a class) Order: Aranae

Mygalomorph Spiders Theraphisidae (Tarantulas) go to Mt. Diablo (Bird eating spiders) go to South America Dipluridae Aggressive False Tarantula (Calisoga longitarsus) Trapdoor Spiders Atypidae Turret Spiders (Purseweb Spiders)

Araneomorph Spiders Uloboridae Triangle spider (Hyptiotes sp.) : Sheet Web Weavers Bowl & Doily Spider Filmy Dome Spider Agelenidae: Funnel Web Spiders Desidae (spiders that make messy webs on outside of houses) Badmuna sp. (From Australia) Theridiidae: Comb-footed Spiders Black Widow or Western Widow () False Widow () House Spider ( tepidariorum) Pholcidae: Cellar Spiders () Araneidae: Orb Weavers Pumpkin Spider (Araneus trifolium) Yellow & Black Garden Spider (Argiope aurantia) Silver banded Garden Spider (Argiope trifasciata) Debris Spider (Cyclosa sp.) Labyrinth or Condo Spider (Metepeira sp.) Long-Jawed Spider (Tetragnatha sp.) Zygiella Lycosidae : Wolf Spiders Salticidae: Jumping Spiders Thomisidae: Crab Spiders 8 INTERNAL of a SPIDER

9 EXTERNAL ANATOMY of a SPIDER

10