Common Names

For many, one of the most frustrating things about observing spiders is the fact that most species are not referred to by “common names.”  These easy to remember English names have been given to all bird species, butterfly species, as well as many other creatures familiar to us.

Only a few spiders have been given such names. There is actually an official committee (Committee on Common Names of Arachnids of the American Arachnological Society) that was created to provide standardized English names for species of arachnids of medical or economic importance, or those common enough to be familiar.  Anyone who has given a talk on spiders to a general audience will immediately recognize the value of common names.  Trust me, I’ve given more than my share of programs punctuated by names such as “Parasteatoda tepidariorum” or “Agelenopsis pennsylvanica.”

Most spider species are tiny and inconspicuous. Well over half of the described species in North America north of Mexico never achieve a body length greater than 2 or 3 mm (~1/16 – 1/8 inch).  These little spiders are so difficult to see well that, even if we gave them descriptive English names, the features implicit in the name would be too inconspicuous to notice. They simply wouldn’t be useful, even for experienced naturalists.

But, as the existence of the aforementioned committee implies, some spiders do have useful  English names that are commonly used.  Here are a few examples.

The bowl-and-doily spider is the first spider common name that many of us learned. The phrase bowl-and-doily refers the iconic web of this species.  It does indeed have a bowl shaped sheet web, suspended over a relatively flat lacy sheet web.

the web of a bowl and doily spider

the web of a bowl and doily spider

There is actually more to this web than the obvious bowl and doily. There is also a non-sticky tangle above the bowl.  The purpose of the tangle is to intercept the flight of potential prey. When a hapless fly blunders into the tangle, it is often knocked out of the air and tumbles down to the surface of the bowl.  The vibrations of this motion are detected by the resident spider and she is usually waiting just below the bowl precisely where the fly lands.  In a flash she strikes up through the silk web and envenomates the fly.  This is not a fair contest and the fly is quickly killed and drawn through the bowl to provide a feast for the resident spider. Here is another photo of such a web taken on a particularly dewy morning that reveals the tangle above the bowl.

the web of a bowl and doily spider showing the tangle of threads above the bowl

the web of a bowl and doily spider showing the tangle of threads above the bowl

The resident spider is relatively small.  She is most often found hanging below the web.  Her dark coloration with white bands is actually somewhat cryptic in this situation.

female bowl and doily spider (Frontinella communis) hanging under her bowl ready for action

female bowl and doily spider (Frontinella communis) hanging under her bowl ready for action

For a close-up view, here is an illustration of her from Common Spiders of North America drawn by Steve Buchanan.

female bowl and doily spider (Frontinella communis) illustration by Steve Buchanan

female bowl and doily spider (Frontinella communis) illustration by Steve Buchanan

If you are lucky enough to encounter a courting pair, the male often stands out in contrasting reddish coloration.  The following beautiful photo was made by Sarah Rose.  In this case the red male is closest to us with his potential mate in the back.

A pair of bowl and doily spiders, red male in front, by Sarah J. Rose

A pair of bowl and doily spiders, red male in front, by Sarah J. Rose

So why the quaint name “bowl and doily?”  This is actually a fairly old common name. It dates to a time when finding a bowl of candy sitting on top of a crocheted doily would have been commonplace in your grandmother’s parlor. The name is based on the fancied resemblance of the web to this scene. I staged this “re-creation” below.

"staged" bowl-and-doily meant to evoke domestic history

“staged” bowl-and-doily meant to evoke domestic history

Here is another example of a common name based on a distinctive web.  The filmy dome spider (Neriene radiata).  Her web is usually built in the forest, often in the shady understory.  The web is composed of very fine silk strands and is quite delicate.  It can be difficult to see the web at all.  But when there is enough dew condensation the dome shaped sheet is revealed.

web of a filmy dome spider

web of a filmy dome spider

Here is a more dramatic photo by Alan Knowles. He found the spider on a very dewy morning and photographed it with a flash. You can see (if you look closely) that the spider is resting under her dome near the top at the left side.

Alan Knowles photo (scanned) of a filmy dome spider in her dewy web enhanced by flash

Alan Knowles photo (scanned) of a filmy dome spider in her dewy web enhanced by flash

Here is the illustration from B.J. Kaston’s classic How to Know the Spiders.  It reveals not only the dome but also the tangle of knock-down strands above the web.

illustration of a filmy dome spider's web, from B.J. Kaston's How to Know the Spiders

illustration of a filmy dome spider’s web, from B.J. Kaston’s How to Know the Spiders

The occupant of this beautiful delicate web is another small sheet-weaving species Neriene radiata.  The sharp-eyed reader will notice that the species scientific name has changed since B.J. Kaston’s book was first published (1953, 1972).  Here is a female filmy dome spider hanging in her (invisible) web.

female filmy dome spider (Neriene radiata) hanging in her nearly invisible web, finishing her meal

female filmy dome spider (Neriene radiata) hanging in her nearly invisible web, finishing her meal

And here is another photo made by Sarah J. Rose of a pair sharing a dome.

A pair of filmy dome spiders, male on left, by Sarah J. Rose

A pair of filmy dome spiders, male on left, by Sarah J. Rose

When the pair come together to mate the male reaches out with his palp and transfers sperm into her gonopore on the ventral side (at the top in this pose) of her abdomen.  In this photo you can see the expanded hematodocha at the tip of his palp. The fluid that inflates this bag-like structure is not the semen. It is actually hemolymph fluid (blood) and the pressure from this inflated sac squeezes the actual semen out of its reservoir and into the female.

pair of filmy dome spiders mating, note the expanded hematodocha of the male

pair of filmy dome spiders mating, note the expanded hematodocha of the male

Here is a close up illustration of a female filmy dome spider from Common Spiders of North America.

female filmy dome spider (Neriene radiata) illustration by Steve Buchanan

female filmy dome spider (Neriene radiata) illustration by Steve Buchanan

Here is a third sheet-weaver example of a common name derived from the web structure built by the spider.  This one is called the hammock spider based on a fanciful interpretation of the sagging sheet suspended from branches at the edges.  I’ll include a photo of a web and also a real hammock for comparison, you be the judge.

web of a hammock spider (Pityohyphantes costatus)

web of a hammock spider (Pityohyphantes costatus)

cotton fiber hammock

cotton fiber hammock

The hammock spider is quite a bit larger than either of the others described above. She is a striking spiny-legged spider with a distinctive jagged dark band down the middle of her abdomen. and a dark central mark on the top of her cephalothorax that splits into two lines near the eyes.

hammock spider (Pityohyphantes costatus) female eating a prey item in a retreat under a culvert at the edge of her web

hammock spider (Pityohyphantes costatus) female eating a prey item in a retreat under a culvert at the edge of her web

hammock spider (Pityohyphantes costatus) in her web that has been thoroughly coated with dust motes

hammock spider (Pityohyphantes costatus) in her web that has been thoroughly coated with dust motes

Another close up from Common Spiders of North America.

female hammock spider (Pityohyphantes costatus) illustration by Steve Buchanan

female hammock spider (Pityohyphantes costatus) illustration by Steve Buchanan

Early in the spring (at the time I’m writing this) the hammock spiders are usually hiding in a loose silken retreat under a leaf.  These individuals are often sub-adult (one molt away from maturity).  With the arrival of truly warm days they will construct their webs, perhaps capture a few insects and then molt into the adult.  I’ve captured adult females in Ohio between late May and mid September.  Most of the individuals I encounter in the late autumn, winter, and early spring, are immatures.

My last example of a spider with a common name based on a web is the lattice orbweaver (Araneus thaddeus). This spider is normally hidden from view.  They hide in a tightly folded leaf retreat. The entrance to the retreat is a tubular silken structure with walls that appear a lot like the criss-cross pattern found in lattice work.  In this first photo you can see the orb itself, which is connected to the retreat by a “signal lines” which transmit vibrations to the spider. If she detects that a prey has been captured in the orb, she rushes out to grab a meal.

the orb web of a lattice orbweaver (Araneus thaddeus)

the orb web of a lattice orbweaver (Araneus thaddeus)

The spider is waiting well back in the retreat.

female lattice orbweaver (Araneus thaddeus) finishing a meal in her retreat

female lattice orbweaver (Araneus thaddeus) finishing a meal in her retreat

Here is a shot of the signature “lattice” of the retreat entrance tube.

the lattice-like retreat tube of a lattice orbweaver

the lattice-like retreat tube of a lattice orbweaver

Maybe it takes a bit of imagination, but I can see a resemblance to a garden lattice.

a garden lattice

a garden lattice

Even if you don’t recognize the lattice pattern, you will be rewarded well if you glimpse this beautiful little orbweaver. She is one of the most widespread species in Ohio, but because she doesn’t usually expose herself in the open, she isn’t as familiar as some others.

female lattice orbweaver (Araneus thaddeus) illustration by Steve Buchanan

female lattice orbweaver (Araneus thaddeus) illustration by Steve Buchanan

Sometimes common names are given to a group of very similar, or related, spiders. For example the grass spiders (the 13 species of Agelenopsis, family Agelenidae).  These spiders are familiar because they build webs at the edge of lawns or near trails.  On dewy mornings, condensation makes the webs conspicuous.  The web has an obvious funnel-shaped retreat where the spider is lurking.

photo of grass spider web

web of a grass spider (Agelenopsis) with its funnel-shaped retreat

It is tough to identify which species of grass spider lives in the web, but at least this name gives you a useful handle for your observations.  In this case, the occupant was the most common of the five species of grass spiders found in Ohio, Agelenopsis pennsylvanica. Here is a photo of this species.

an adult female grass spider Agelenopsis pennsylvanica on her web

an adult female grass spider Agelenopsis pennsylvanica on her web

As of this post, there are 80 common names for spiders in Ohio, roughly 12 percent of the 653 species known for our state.


Sources:

Kaston, B.J. 1978. How to Know the Spiders. WCB McGraw-Hill, Boston, 272 pp.

 

Trypoxylon vs. Parasteatoda

If you live in eastern North America there is probably a life-and-death struggle going on near you between the local spiders and a particular wasp.  The wasp is famous for its remarkable mud nests, the beautiful Pipe Organ Mud-dauber Wasp (Trypoxylon politum). This is one of the most frequently encountered predators of spiders in our region.  It builds conspicuous mud nests with a tubular shape that some people think resemble organ pipes (because of their varying length and parallel arrangement).

large array of Trypoxylon nest tubes said to resemble a pipe organ

large array of Trypoxylon nest tubes said to resemble a pipe organ, note the holes (dark) where young wasps have successfully emerged out of their chambers

pipe organ pipes (shown upside down to emphasize the resemblance)

pipe organ pipes (this photo is shown upside down to emphasize the resemblance)

This wasp builds its pipe organ mud tubes to house her family.  The carefully constructed tubes are built of wet mud that she collects from the neighborhood. Each load of mud is added to the tube creating a series of ridges, looking almost like the coils of hand made coil-built pottery.  When dry, the tubes become quite hard and durable.

one old tube with new extension and one fresh Trypoxylon tube

one dry tube with a newer wet extension and one fresh Trypoxylon tube

Trypoxylon female flying to nest with load of wet mud

Trypoxylon female flying to nest with load of wet mud

Trypoxylon female landing at nest with mud

Trypoxylon female landing at nest with mud

Trypoxylon female at nest adding mud to lip

Trypoxylon female at nest adding mud to lip

Here is another series of photos of a female arriving with a mud ball and spreading the mud along the edge of the tube forming a new extension.

Trypoxylon female arrives with mud ball, male attending below

Trypoxylon female arrives with mud ball, male attending below

Trypoxylon politum female adding mud to her tube, male attending below

Trypoxylon politum female adding mud to her tube, male attending below

Trypoxylon politum female adding mud to her tube, male attending below

Trypoxylon politum female adding mud to her tube, male attending below

Trypoxylon politum female adding mud to her tube, male attending below

Trypoxylon politum female adding mud to her tube, male attending below

When a tube is ready, she will fly out and capture a spider. After she captures a spider, she paralyzes it with a sting, then stuffs it into the tube. The spiders aren’t dead, just immobilized.  They are alive and will remain so until they are eaten by the baby wasp (larva).  As she provisions her nest tubes, there is often a second wasp seen hanging around near the entrance.  This is a male Trypoxylon, guarding the female and her nest.  I assume he is likely protecting his mate from other males who might try to mate with her.

male Trypoxylon wasp guarding entrance to tube with female inside

male Trypoxylon wasp guarding entrance to tube with female inside

fresh tube of Trypoxylon wasp with pair present, male visible at entrance

fresh tube of Trypoxylon wasp with pair present, male visible at entrance

When the mother wasp has provided enough zombie spiders as food she will lay an egg on one of the spiders then seal up that section of the tube. The pair of wasps actually mate inside the tube and the male holds the female as she lays the egg.  The female now seals the zombie spider prey and her egg by making a mud partition.  Eventually each tube will have several compartments, each with a supply of paralyzed spiders and wasp eggs.

back view of Trypoxylon nest tubes revealing wasp pupal cases and some spider bodies (at left)

back view of Trypoxylon nest tubes revealing wasp pupal cases and some spider bodies (at left)

The egg will hatch into a larva and begin to devour the paralyzed spider.  As it eats, it grows and molts. The larva looks a bit like a maggot at this stage, munching through one “fresh” paralyzed spider after another and growing.  After eating the entire cache of zombies, the larva will construct a survival capsule called a cocoon and molt into the pupa.  At this stage the little wasp looks like a tightly folded pale mummy sealed in a brownish sarcophagus.

dissected Trypoxylon tube revealing successful emergence

dissected Trypoxylon tube revealing successful emergence

In her article about the variable life history of Trypoxylon politum, Jane Brockmann has published a nice description of the life cycle of these wasps*.  The egg hatches in a couple of days, consumes the prey spiders in about five days, then spins a cocoon (which hardens into a dark brown capsule-shaped pupal case in a few days).  When metamorphosis into a wasp is complete, the young wasp emerges from its pupa and digs its way out of the mud chamber.  According to Brockmann, some of the young wasps emerge about six weeks after pupation, in the same summer.  Others enter a “resting stage” called diapause.  These individuals will spend the winter in the tube and emerge the following spring.

This wasp, aka Trypoxylon is skilled at capturing spiders out of their webs.  Her favorite prey are small orb-weaving spiders.  In the mud nests that I’ve dissected from around my house, the spider victim most often taken is Neoscona arabesca (aka arabesque orbweaver).  Sometimes the wasps also take immature Araneus marmoreus (aka marbled orbweaver) that are about 1/2 grown (roughly the same size as adult N. arabesca).  Perhaps the size is the critical feature that the wasp is using to make her choice.

dissected Trypoxylon tubes revealing dead spider bodies of Neoscona arabesca

dissected Trypoxylon tubes revealing dead spider bodies of Neoscona arabesca

Neoscona arabesca female (in her web)

Neoscona arabesca female (in her web)

So it is clear that this wasp is a real threat to the local spiders.  Imagine my surprise when I noticed one of the wasps (the male) hanging as a prey item in the web of one of the Common House Spiders (Parasteatoda tepidariorum) on the side of our house.

Common house spider with male Trypoxylon wasp prey

Common House Spider with male Trypoxylon wasp prey (also note that some of her spiderlings are emerging from another egg case above)

Somehow it seems like poetic justice to have a spider capture and kill a wasp that specializes in eating other spiders.  It isn’t clear to me that Trypoxylon is capable of capturing Parasteatoda.  The typical prey of Trypoxylon are orb weavers with their flat circular webs.  Thus the orbweaving spiders are exposed to direct attack.  In contrast, the web of Parasteatoda is a complex tangle of nearly invisible threads filling a three-dimensional space.  The spider hangs within this tangle.  For the wasp, it would be very difficult to approach the spider without getting tangled in the web, and potentially being captured. Maybe this is how this spider predator became spider food.  Here is a closeup shot.

Common house spider with male Trypoxylon wasp prey

Common house spider feeding on a male Trypoxylon wasp prey

Remarkable names are the rule in “scientific” terminology.  Sometimes they are used enough by enthusiasts that they become the “common name” for the species.  This is the case for both of these interesting animals.  The Pipe Organ Mud-dauber Wasp (Trypoxylon politum) is often referred to as just “Trypoxylon,” and the Common House Spider (Parasteatoda tepidariorum) is often referred to as Parasteatoda.


Reference:

Brockmann, H. Jane. 2004. Variable life-history and emergence patterns of the pipe-organ mud-daubing wasp, Trypoxylon politum (Hymenoptera: Sphecidae). J. of the Kansas Entomological Soc., 77(4): 503-527.

the enemy of our enemy is our friend

Some of you will know, and possibly be plagued by a newly introduced pest insect, the Brown Marmorated Stink Bug (Halyomorpha halys).  This animal was accidentally introduced in to the United States from Asia in 1998. They are an agricultural pest, and when they mass for overwintering, they can be also be really annoying.  Often hundreds concentrate in and around buildings.  When annoyed they produce a foul smell that probably evolved as a defense against predators.

Brown Marmorated Stink Bug (Halyomorpha halys) crawling along the baseboard.

Brown Marmorated Stink Bug (Halyomorpha halys) crawling along the baseboard.

Today’s blog entry is the story of how having spiders around the house can help. Several of the most common household and yard spiders in Ohio are known to eat Brown Marmorated Stink Bugs. Here are photos of just a few that I’ve caught in the act.

Long-bodied Cellar Spider (Pholcus phalangioides) feasting on a Brown Marmorated Stink bug that it found in our basement.

Long-bodied Cellar Spider (Pholcus phalangioides) feasting on a Brown Marmorated Stink bug that it found in our basement.

Bold Jumper (Phidippus audax) feeding on a Brown Marmorated Stink Bug on our back porch.

Bold Jumper (Phidippus audax) feeding on a Brown Marmorated Stink Bug on our back porch.

Common House Spider (Parasteatoda tepidariorum) with a Brown Marmorated Stink Bug prey found on our back porch this spring.

Common House Spider (Parasteatoda tepidariorum) with a Brown Marmorated Stink Bug prey found on our back porch this spring.

So at least three good reasons to keep those spiders around the house!  It reminds me of the Machiavellian-like statecraft statement “the enemy of our enemy is our friend.”

Spiders in Winter

It is spring as I write this, so I’m a bit behind with this blog entry.  You may have been wondering about where all those spiders that you saw in the autumn went during the winter.  Many of them came to the end of their annual life cycle and died.  The species with this lifestyle have already laid their eggs; the future generation will pass the winter in an egg case.

unknown spider egg case

unknown spider egg case found under the leaf litter

Trachelas tranquillus with her egg case

Trachelas tranquillus with her egg case

Phururotimpus sp? egg case

Phururotimpus sp? egg case

Steatoda triangulosa with egg cases

Steatoda triangulosa with egg cases hidden under a wooden shelf

Philodromus imbecillus female guarding an egg case, also with previous cases (now empty)

Philodromus imbecillus female guarding an egg case, also with previous cases (now empty)

Enoplognatha ovata with her egg case

Enoplognatha ovata with her egg case under a leaf

common house spider (Parasteatoda tepidariorum) with her egg case

common house spider (Parasteatoda tepidariorum) with her egg case

These tiny spiderlings which emerge in the early spring are so small and inconspicuous that we hardly notice them. Other spiders that emerged from eggs laid earlier in the season may survive the winter as immatures or subadults. When they start moving around in the spring they are large enough to be noticeable.

Bold jumper (Phidippus audax) an immature emerging in early spring

Bold jumper (Phidippus audax) an immature emerging in early spring

Leucauge venusta immature

Orchard Orbweaver (Leucauge venusta) immature in early spring

Drassyllus sp? subadult male

Drassyllus sp? subadult male that was found in a shed in early spring

Cheiracanthium mildei subadult male

Yellow Sac Spider (Cheiracanthium mildei) subadult male found indoors in December

The eggs, early-state spiderlings inside the egg case, emerged young spiders, and sometimes overwintering adult spiders often have cryoprotectant compounds in their cells and hemolymph (blood). These compounds either act like anti-freeze (lower the freezing point), or prevent the formation of large ice crystals that would damage cell membranes.

Some species of spiders may live several years and can survive the winter in a retreat or burrow.  Retreats are usually silk cocoons hidden under bark, logs, rocks, or leaf litter.  Very often these are near the ground where temperatures are moderate.  Even under just a few inches of soil and debris, winter temperatures are much milder than above the surface. If there is a layer of snow on the ground, it can act as additional insulation from cold air.  Water and ice are excellent buffers against extreme cold.

A few species can tolerate cold so well that even full-sized adults just find a nook or cranny and freeze in place.  When the weather warms, they thaw and emerge.

Perhaps most remarkably, some spiders are “active” during the winter. They may take advantage of a warm winter day to wander over the snow.  It isn’t clear what they are doing, but very few prey are active, so they may just be dispersing.

Allocosa funerea female

a small wolf spider (Allocosa funerea) female found walking on the snow

Tetragnatha viridis subadult male

a long-jawed orbweaver (Tetragnatha viridis) subadult male found and photographed by David Hughes at Clear Creek Metropark (Fairfield County, Ohio) in late January 2016

The most famous “winter active” spiders are the tiny denizens of the leaf litter. These animals may even molt into mature adults during the winter months.  They take advantage of the relative “warmth” under layers of dead leaves and other debris on the ground. It there is snow cover, so much the better. The epigeal (soil surface) environment is actually quite hospitable to them. In Ohio deciduous forests the leaves that fell during the autumn have been decomposing by the action of fungi and bacteria.  Tiny animals that feed on the decomposing leaves, or on the decomposer organisms, become quite abundant by mid-winter. Other small creatures feed on these, including many species of spiders.

Many of these winter spiders are members of the sheetweaver family (Linyphiidae). They come in a variety of sombre browns and blacks, but quite a large proportion have bright orange coloration.  I’d love to know why orange is such a common color.  Here is a gallery of tiny sheetweavers, none larger than 2.5mm (~1/8 inch) long.  These sheetweavers often find mates and reproduce during the winter.

Origanates rostratus male

Origanates rostratus male

Lepthyphantes leprosus male

Lepthyphantes leprosus male

Hypselistes florens female

Hypselistes florens female

Grammonota inornata female

Grammonota inornata female

Centromerus denticulatus male

Centromerus denticulatus male

Bathyphantes pallidus male

Bathyphantes pallidus male

Gonatium crassipalpum male

Gonatium crassipalpum male

Some of the “larger” sheetweavers of the family Linyphiidae will emerge, build webs, and hunt as soon as the early spring weather permits.  Below is an subadult male Neriene variabilis.  As an adult he will be only about 4 to 4.5 mm (< 1/4 inch) total body length, but this is still twice as large as the dwarf sheetweaver spiders shown above.

Neriene variabilis subadult male

Neriene variabilis subadult male in his web in mid March

In addition to the sheetweavers, there are a number of other small spiders that are active on the ground surface under leaf litter.

immature hahniid, possibly Neoantistea

A tiny immature combtailed spider (Family Hahniidae), possibly Neoantistea that I found in leaf litter in the late autumn.  It was probably disturbed from a tiny web among the leaves.

Phrurotimpus borealis immature

A tiny ground-active spider in the dwarf antmimic family, (Phrurotimpus borealis) immature, found running among the leaves in autumn and winter in Ohio. This may be one of the most common spiders in these situations

Castianeira probably longipalpa immatur

Castianeira probably longipalpa immature posed on a piece of slate for this photo. These spiders have often been found among the leaf litter in Ohio woodlands and forests during winter

One last note about large spiders in winter, sometimes they do come out of hiding.  When the weather is unusually nice they may show up right on the surface.  Late last year I found the beautiful wolf spider, shown in the photo below, out in the tall grass next to a road while I was out “scouting” for an upcoming Christmas Bird Count.  She was presumably hunting. There were other small wolf spiders in the area, great prey for a big one like this.

Rabidosa punctulata adult Female

A wolf spider (Rabidosa punctulata) adult Female, this photo is of her “posed” on a piece of wood but she was found out in the grass in early December 2015.

spidering on Gibraltar Island

For the past few summers I’ve taught a Spider Biology course (EEOB 5210) at The Ohio State University’s F.T. Stone Laboratory on Gibraltar Island in Lake Erie.  The course will be offered again this summer (2016), from July 31 through August 6.  This is a regular Ohio State University course, providing two semester hours of credit for upper division or graduate students. With permission, the course can also be taken as a non-credit workshop for those not currently enrolled at OSU.

Gibraltar Island, Lake Erie, Ohio

Gibraltar Island, Lake Erie, Ohio

main Stone Laboratory building

main Stone Laboratory building

Now is the time to investigate signing up for the course. One reason is that many students can benefit from scholarships that provide partial support for the course costs. These scholarships are supported by the Friends of the Stone Laboratory. The deadline for a scholarship application this year is March 3, 2016.

welcome sign, F.T. Stone Laboratory

welcome sign, F.T. Stone Laboratory

This is an intensive, residential, one week course that introduces spiders and spider research to college students. Past classes have included undergraduates, graduate students, as well as teachers and other interested naturalists.  We all live and breathe spiders for seven days, beginning, after introductions, with an evening spider walk around the grounds of the laboratory on Gibraltar Island on Sunday night. Most of the students have little experience with spiders; but some have been keen spider enthusiasts, even a few academic arachnologists.

Larinioides patagiatus female hanging from a web on the outside of the laboratory building

Larinioides patagiatus female hanging from a web on the outside of the laboratory building

Observing some species of spiders requires a bit of encouragement. One simple method is to gently wiggle a brush in the silk “signal” lines running out from the retreat.  For viewing the tubeweb weaver (Ariadna bicolor) this technique can be very successful. Below you can see her attacking the brush. Eventually we managed to lure one completely out of her tube.

luring a tubweb spider (Ariadna bicolor) from her tube retreat

luring a tubweb spider (Ariadna bicolor) from her tube retreat

eventually she leaves her tube and bites the brush

another Ariadna leaves her tube and bites the brush

Others are found out wandering on the walls of the buildings or other structures. These include the day-active jumping spiders.  Here are a couple of photos of the Zebra Jumper, a common harmless jumper found on Gibraltar Island.

zebra jumper (Salticus scenicus) female

zebra jumper (Salticus scenicus) female

zebra jumper (Salticus scenicus) female

zebra jumper (Salticus scenicus) female

Each day begins with morning lectures followed by afternoon laboratory and field work. During the evenings early in the week, we often convene to search for nocturnal spiders around the island. As the week progresses the students begin to focus on their individual research projects, and much of this work is done in the late afternoon and into the night. Of course, many spiders are nocturnal, so this necessitates field work at that time of day.
Monday’s first afternoon laboratory is an intensive introduction to spider anatomy with way-too-many unfamiliar anatomical terms. By the end of the week, the students all eventually master these, and are conversing in phrases like “median ocular area” and “retromarginal teeth” or “long posterior spinnerets.”

students working in the lab

students working in the lab

Christopher Klemm working with spider identification key

Christopher Klemm working with a spider identification key

The course is an exploration of the biology of spiders (Order Araneae), but I try to create a relaxed informal environment for learning. Topics include functional anatomy, senses and perception, behavior, webs and web-building, identification, classification and relationships, field techniques, and ecology.

Michael Chips installs a pitfall trap as the class looks on

Michael Chips installs a pitfall trap as the class looks on

Sarah Rose checking a pitfall trap

Sarah Rose checking a pitfall trap

collecting spiders from beating sheet

collecting spiders from a beating sheet

Lectures are profusely illustrated with photos and videos of spiders and spider behavior. There is a tradition of an evening “movie night” with silly commercial hits such as the John Goodman classic: Arachnophobia (1990). Even watching this movie can be a spider-nerd challenge. For example: there several different families of spiders represented as one species in the film. It is difficult to identify them from their brief furtive appearance on the big screen.

Arachnophobia publicity photo

Theatrical release poster by John Alvin

Spider identification is a tricky skill to master. We begin in the field “spidering” similar to beginning birding, focus on the large and conspicuous species. The big orbweavers, which are so very common on Gibraltar, such as the Furrow Orbweaver (Larinioides cornutus) and its relative Larinioides patagiatus are among the first ones we find. These big spiders are the “Great Blue Herons” of arachnology.

furrow orbweaver (Larinioides cornutus) female

furrow orbweaver (Larinioides cornutus) female

furrow orbweaver (Larinioides cornutus) female

furrow orbweaver (Larinioides cornutus) female

furrow orbweaver (Larinioides cornutus) male searching for a female

furrow orbweaver (Larinioides cornutus) male searching for a female

We usually see plenty of the abundant introduced “House Sparrow” of spiders, Common House Spider (Parasteatoda tepidariorum).

common house spider (Parasteatoda tepidariorum) with a bug prey item in the corner of the lab

common house spider (Parasteatoda tepidariorum) with a bug prey item in the corner of the lab

Students quickly learn that color and pattern aren’t often useful for spider ID; shape & behavior are better clues. With practice, subtle features like eye-arrangement and spinneret structure are recognizable.  For some groups, a quick look at the “face” can be distinctive.

wolf spider face and jumping spider face

wolf spider face and jumping spider face

Field work in this course includes work around Gibraltar island, as well as a field trip to sites on South Bass Island. We observe, and sometimes collect spiders on these trips. Some of the specimens are incorporated into the individual student collections, others are used in individual projects.

Agelenopsis, the grass spider after being lured out of her retreat

Agelenopsis, the grass spider poses in the open after being lured out of her retreat

One of the first lessons in a course such as this one is that “daddy-long-legs” aren’t spiders at all. They are sort of cousins to spiders, members of another group, the harvestman (Order Opiliones).  Being arachnids, they share many features with spiders, for example they have four pairs of legs.

Harvestman, not a spider, but a related arachnid in the Order Opiliones

Harvestman, not a spider, but a related arachnid in the Order Opiliones

Along the cobbles of the shoreline in the evenings it is often relatively easy to find larger wolf spiders, such as this Pardosa.

wolf spider (Pardosa lapidicina)

wolf spider (Pardosa lapidicina)

immature hammock spider (Pityohyphantes costatus) with a midge prey

immature hammock spider (Pityohyphantes costatus) with a midge prey

The spider below looks similar, but students learn to use a magnifying glass to examine distinctive features such as the high clypeus of Pityohyphantes compared to the low one of Tetragnatha.

Tetragnatha laborious female

Tetragnatha laboriosa female

Some spiders do well in the laboratory and make good captive study subjects. One example is the fishing spider (Dolomedes tenebrosus), below in the field, and then a close up of the same gal feasting on a mayfly in captivity.

fishing spider (Dolomedes tenebrosus)

fishing spider (Dolomedes tenebrosus)

captive fishing spider (Dolomedes tenebrosus) eating a mayfly

captive fishing spider (Dolomedes tenebrosus) eating a mayfly

Some of our finds are common introduced species, such as this female Enoplognatha ovata with her large egg case.

Enoplognatha ovata with her egg case

Enoplognatha ovata with her egg case

Others are quite rare, like this female running crab spider (Philodromus imbecillus) which represented the third locality record for the state when we found it on the field trip along the Jane Coates Wildflower trail.  This site is maintained by the Lake Erie Islands Conservancy.

Philodromus imbecillus female guarding an egg case, also with previous cases (now empty)

Philodromus imbecillus female guarding an egg case, also with previous cases (now empty)

One key component of the course are the individual projects. Each student chooses a topic of interest and investigates it in some detail. They collect data and conduct analysis. At the end of the course each student summarizes their results in a brief presentation to the class. For many students, the individual project is the highlight of the course. It is a chance for them to delve deeply into a particular topic suited to their personal interests. Past topics have included census work around windows on the research building, courtship behavior of jumping spiders, and variation in web structure. One of last year’s students, Zachary Diehl focused on spider heart rates.

from Twineline Fall/Winter 2015 p 17

from Twineline Fall/Winter 2015 p 17

The perennial stars of the course are the often charismatic jumping spiders (family Salticidae). They are the “Blue Jays” of arachnology, conspicuous, colorful, active, and overall fascinating predators.

Sara Klips observing jumping spider behavior as part of her research project

Sara Klips observing jumping spider behavior as part of her research project

jumping spider (Phidippus putnami) female

jumping spider (Phidippus putnami) female

jumping spider (Colonus sylvanus) female

jumping spider (Colonus sylvanus) female

jumping spider (Phidippus clarus) female

jumping spider (Phidippus clarus) female

dimorphic jumper (Maevia inclemens) female

dimorphic jumper (Maevia inclemens) female

By the end of the week students have achieved the goals of this course and will have:

• learned to appreciate the diversity and relationships among spiders
• learned the functional anatomy of spiders
• become proficient in advanced spider identification
• learned to conduct field study of spiders using standard techniques
• learned to recognize and understand common spider behaviors
• experienced the micro and macro habitat preferences of spiders
• designed and conducted a small research project

Here are a few “group portraits” of our last few Spider Biology courses.

class group portraits, clockwise, 2007, 2012, 2013, 2015

class group portraits, clockwise from the upper left, 2007, 2012, 2013, 2015

Naturally, the impact of any summer course at the F.T. Stone Laboratory on Gibraltar is due to the unique learning atmosphere there. The small classes and intense format mix to create a very special experience for all involved.  It doesn’t hurt that the scenery is spectacular.

sunset viewed from Gibraltar Island

sunset viewed from Gibraltar Island

For more details about this course consult the Stone Laboratory course information page. Anyone with a specific question about this course is welcome to contact me directly.