2009. The Journal of Arachnology 37:306–311
Construction and function of the web of Tidarren sisyphoides (Araneae: Theridiidae)
Ruth Madrigal-Brenes and Gilbert Barrantes: Escuela de Biologı́a, Universidad de Costa Rica, Ciudad Universitaria
Rodrigo Facio, San José, Costa Rica. E-mail: ruthymad@gmail.com
Abstract. In this paper, we describe the construction and function of the double sheet and tangle web of Tidarren
sisyphoides (Walckenaer 1842). Web construction includes several stages: construction of the scaffolding that serves to
support the rest of the web; filling in the dome-shaped and horizontal sheets; and construction of the upper tangle. During
construction of the scaffolding, the spider descends by a pre-existing thread to the substrate, moves a few centimeters and
attaches the dragline, then she ascends by the new thread, doubling the line or attaching it to another thread. The spider
fills in the sheet while walking in an irregular pattern under the sheet, and attaching her dragline using either one or both
legs IV simultaneously to hold pre-existing sheet lines against her spinnerets. During scaffolding construction and filling in
the dome-shaped sheet, the spider returns frequently to the retreat, apparently using the same threads near the retreat each
time. Threads of both the dome-shaped sheet and the horizontal sheet have small drops of viscid material. The dome-
shaped sheet and upper tangle comprise the functional trap of the web, while the horizontal sheet apparently plays only a
little role in prey capture.
Keywords: Web-building behavior, aerial sheet web, web function, viscid threads
Web designs in Theridiidae are strikingly variable (Szlep 1965, suspended in the tangle at the peak of the dome, opening onto
1966; Lamoral 1968; Eberhard 1972, 1981, 1991; Agnarsson the underside of the dome (Eberhard et al. 2008a). Web
2004, 2005, 2006; Eberhard et al. 2008a), and similar designs construction behavior has never been described in Tidarren. The
have evolved independently in different genera, and in different only report of construction of an aerial sheet web is for
species within a genus (Darchen & Ledoux 1978; Eberhard 1991; Achaearanea tesselata (Keyserling 1884) (Jörger & Eberhard
Japyassú & Jotta 2005; Barrantes & Weng 2006a, 2007; Jörger & 2006). This study describes the web construction behavior of T.
Eberhard 2006; Eberhard et al. 2008a). The broad disparity in sisyphoides, and the function of the areas of its web.
theridiid webs is possibly the result of their great flexibility in
microhabitat use, their ability to adjust web design to different METHODS
physical spaces, prey types, and prey availability (Turnbull 1964; We observed web construction behavior of 15 adult female
Eberhard 1990a; Agnarsson & Coddington 2007; Jörger & T. sisyphoides indoors in wire cubes 30 cm on a side, hanging
Eberhard 2006; Eberhard et al. 2008b), and their response to 2 m above the floor from a thin fishing line. The cubes had a
parasitism and predation pressures (Blackledge et al. 2003; wire along each of the diagonals at the top, and one along one
Agnarsson 2004; Barrantes et al. 2008). of the diagonals at the bottom. We collected the spiders with
Webs of theridiid spiders are sometimes described as an their retreats on the campus of the Universidad de Costa Rica,
irregular, three-dimensional structure (Foelix 1996). However, San Jose province (9u549N, 84u039W), Costa Rica. We hung
their webs range from those that are extremely simplified as in each retreat individually from the intersection of the two
Phoroncidia studo Levi (Eberhard 1981), with a web consisting diagonal wires at the top, using silk threads (4–5 cm long) of
of a single sticky line, to extremely complex, three-dimensional the same web. Two spiders did not use the retreats and
webs with aerial sheets, as in Achaearanea disparata Denis constructed webs without them.
1965 (Darchen & Ledoux 1978) and Tidarren sisyphoides We photographed twelve webs each day for several days
(Eberhard et al. 2008a). Despite the diverse array of web (digital camera Olympus SP-510UZ), until each web was
designs and the convergence in some of these designs, the completed. Webs were sprayed with water just before
detailed descriptions of the web-building behavior have begun photographing them to create a better contrast of silk threads
to reveal some patterns in the typical behavior used to against the cubes’ backgrounds. We video recorded the
manipulate lines and in the sequence of lines laid (Benjamin & complete construction of three additional webs using a Sony
Zschokke 2003; Jörger & Eberhard 2006; Eberhard et al. digital camera DCR-HC 96. Recording distance from the
2008b). Knowledge of how three-dimensional webs of spider was intentionally changed during web construction to
theridiids are built is generally fragmentary (Szlep 1965, have either the entire cube in view or close-ups of different
1966; Lamoral 1968; Benjamin & Zschokke 2003), and limited construction behaviors. We searched for sticky droplets on
to only a few genera. threads in five webs from the field. Thread samples from
All webs described for species within the derived genus sheets were collected on slides framed with strips of double-
Tidarren are tangles with aerial sheets (Agnarsson 2004; sided adhesive tape, and density of viscid globules was
Benjamin & Zschokke 2003; Eberhard et al. 2008a). Those of measured following Barrantes & Weng (2006b). We photo-
T. sisyphoides (Walckenaer 1842) (Benjamin & Zschokke 2003) graphed viscid globules present in these threads under a
and Tidarren spp. (see Agnarsson 2004) have been described as compound microscope (digital camera Nikon Coolpix 4500)
lacking viscid threads. The sheet of T. sisyphoides is dome- with a relative humidity of 60%. Viscid globules were then
shaped, with a relatively dense tangle above it (Eberhard et al. placed in a saturated humidity chamber for 40 min and
2008a). The spider hides in a retreat, often a curled leaf, observed under the dissecting microscope for changes in size.
306
MADRIGAL-BRENES & BARRANTES—WEB OF TIDARREN SISYPHOIDES 307
Figure 1.—Web of Tidarren sisyphoides (powdered with talcum) showing the upper tangle, the dome-shaped sheet, and the horizontal sheet.
We videotaped the attack behavior on different prey types work at about 530 h next day (n 5 5). Spiders took from one
to determine the possible function of the different sections of to four nights to construct a complete, functional web,
the web. Each spider was offered a blow fly, a moth, a although some additional threads were certainly added
grasshopper, a damselfly, a bee (Trigona spp.), a katydid, or a subsequently. The time spent in building decreased over
leaf hopper every 2 days. Some prey items were placed directly successive nights. The first night the spiders were nearly
on the lower, horizontal sheet of some webs. We made continually active, spinning different parts of their webs, but
additional observations of the general shape of the web, prey on subsequent nights they began later (between 21 and 23 h),
captured, and attack behavior of spiders in the field. Voucher had longer pauses, and finished earlier (usually at 2 or 3 h).
specimens of the spiders were deposited in the Museo de The spiders’ only construction-oriented diurnal activity was to
Zoologı́a, Universidad de Costa Rica. secure the retreat to the wire frame soon after the retreat was
first placed in the wire frame.
RESULTS Web construction can be roughly divided into five different
Webs of adult spiders.—Adult females of T. sisyphoides stages, some of them not being mutually exclusive: explora-
constructed their webs mostly on large, solitary individuals or tion, suspension of the retreat, construction of the scaffolding,
small groups of Agave sp., Yucca guatemalensis (Agavaceae) and construction of the dome-shaped sheet, and construction of
Monstera deliciosa (Araceae) plants scattered over the campus. the lower horizontal sheet. The spider walked underneath silk
These plants all have large, relatively rigid leaves. Other plants lines at all times during construction. She held her dragline
were seldom used. The webs consisted of a large tangle in which with the tarsus of one leg IV, frequently switching the leg IV
there was a dense, upper dome-shaped sheet; a more or less that held the dragline.
horizontal, much less dense sheet at the bottom; and a retreat at Exploration: The spider began the construction of the web
the top of the dome-shaped sheet in the midst of the tangle by exploring the wire cube. She climbed up to the frame along
(Fig. 1). The dome-shaped and the horizontal sheets were very the threads that secured the retreat, then walked along the
loosely connected at their borders, and there was an empty space horizontal and vertical wires of the frame, attaching her
without threads under the dome in which the spider moved freely dragline at irregular intervals and occasionally returning to the
during prey capture. The dense, irregular tangle above the dome- retreat. Sometimes the spider descended beyond the wire
shaped sheet connected the dome to the substrates or to thick, frame, from 30 cm to nearly one meter, hanging from her
multiple threads suspending the retreat. The border of the dome- dragline, and then climbing back up the dragline to the frame.
shaped sheet was also connected to the substrates nearby (wire While ascending, the spider sometimes packed the slack
frame, or leaves and twigs in the field). The horizontal sheet was dragline into a mass, and a small white mass was observed
rarely connected to leaves or other substrates (3 out of 23). near the point where she reached the frame. More frequently
Web construction.—T. sisyphoides (n 5 15) began construc- she did not reel up the dragline, and attached a loop, or
tion of the web between 1730 to 1830 h and ended the night’s sagging threads to the wire. Occasionally the spider descended
308 THE JOURNAL OF ARACHNOLOGY
a second time. All spiders but one did not descend in this way
from the frame during the exploration stage. The complete
exploratory phase lasted 15–30 min.
Anchoring the retreat: After exploration, the spider began to
reposition the retreat. First the spider walked up the line
supporting the retreat and along a horizontal wire of the upper
wire frame, away from the retreat, until she reached a vertical
wire. The spider then descended a few centimeters along the
vertical wire and attached the thread from the retreat to the
wire. The spider often reinforced this line by walking back to
the retreat on the same thread, doubling it. Some of these
threads were attached to the wire frame above the retreat, but
others were attached to the vertical wires either at the level of
the retreat or a few centimeters below it. Then the spider broke
threads attached to the upper section of the retreat, causing it
to drop approximately 1 cm. This sequence was repeated
several times until the retreat was moved up to nearly 10 cm
downward from its original position, and was reoriented so
that its opening was directed downward. The broken lines
were occasionally packed. In these cases, the spider moved
along another line while reeling up the cut line. She packed the
loose line with her legs II and III, and then attached the
whitish mass of silk to the wire frame or to another thread.
With the retreat in position, the spider began to spin threads
from the top of the retreat to the upper wires, within the nearest
5 cm of the crisscrossing point of the diagonal wires. These
threads were frequently reinforced by the spider walking back
and forth, up to five times, on the same threads between the
retreat and the furthest attaching point, forming thick cables
that were clearly distinguishable from other threads. During
construction of this cable, the spider was frequently observed
attaching the new threads to those previously made. Construc-
tion of other sections of the web did not begin until the retreat Figures 2, 3.—Behavioral sequences during web construction. 2.
was securely suspended from the upper section of the wire frame. Placement of threads during the scaffolding construction. The numbers
Construction of the scaffolding: Immediately after suspend- (1a–5a and 1b–4b), arrows, and dotted lines mark the sequence and
ing the retreat, the spider began to construct the scaffolding direction of movements of the spider during lines placement. Dashed
for the dome-shaped sheet. She first spun threads that lines indicate the pre-existing threads and solid lines indicate newly
placed threads. 3. Two different paths of the spider as she filled in the
extended from the retreat opening, or near to it, to the wire
dome-shaped sheet (100 s each traced from video images recorded
frame. Additionally, she spun threads from some point along
looking approximately perpendicular to the plane of the sheet). Black
these threads to the wire frame, so that only five to six (n 5 2 dots indicate the position of the spider every 5 s.
webs) threads converged at (or near) the retreat opening.
These threads were then interconnected, forming a roughly she ascended, producing a double thread (Fig. 2: 1b–4b), or
conical scaffolding just below the retreat. others to another thread (Fig. 2: 1a–5a).
To spin the first threads of the conical scaffolding, the When the spider had spun most lines (lines were difficult to
spider walked along one of the threads from which the retreat observe and were not counted) forming the conical scaffolding,
was suspended and then descended by one of the vertical she connected these lines, and also connected them to the lines
wires. She then either attached her dragline to the vertical wire suspending the retreat. She also spun additional lines connecting
or continued to descend to the horizontal, bottom wire frame the middle part of the retreat to pre-existing lines. The lines
where she attached the dragline, touching her spinnerets connecting the scaffolding of the dome-shaped sheet to the
repeatedly on the side of the wire facing the web or on the side retreat suspension lines and to the upper section of the wire cube
away from the web. Once the thread was attached, the spider constituted part of the upper tangle. Video recordings showed
ascended by the thread she just had created and attached the that when attaching the dragline to another line, the spider held
new thread to it, producing a double line, or else she attached the dragline with one leg IV, while ipsilateral legs III and IV
the new thread to another thread she encountered on the way grasped the other line, bringing it toward the spinnerets at the
up, usually a few centimeters away from the retreat opening. same time that she bent her abdomen ventrally toward the line to
Only rarely, this second thread was attached at the retreat touch it with her spinnerets.
opening. After some lines were present below the hub, the Construction of the dome-shaped sheet, the horizontal sheet,
spider descended by a previous thread, walked 2–4 cm along and upper tangle: After the spider had constructed the
the wire, attached her dragline, and ascended by this new scaffolding, she filled in the dome-shaped sheet. The process
thread. This new thread was sometimes attached to the thread of filling in this sheet alternated with the construction of the
MADRIGAL-BRENES & BARRANTES—WEB OF TIDARREN SISYPHOIDES 309
horizontal sheet and with the upper tangle. All spiders
constructed the dome-shaped sheet in two phases: first the
spider wove a complete but sparse dome-shaped sheet; then
she filled in the spaces in this sheet. The sparse dome-shaped
sheet was constructed in the first (n 5 4) or second night (n 5
11). During the second and third nights, the spiders increased
the density of the dome-shaped sheet and of the threads of the
upper tangle, which mostly consisted of threads connecting the
dome-shaped sheet with the wires above. Construction of the
horizontal sheet did not begin until the dome-shaped sheet had
been partially built. The horizontal sheet was much less
densely woven (Fig. 1).
The spider spent 1–3 min filling in a relatively small section of
the dome-shaped sheet, then moved to a different section,
sometimes on the opposite side of the dome, or sometimes
nearby. After filling in a section, the spider often went up to the
retreat, tapped the egg sac, then moved away to the next web
section to fill in. The repeated visits to the retreat did not
increase the number of threads converging at its mouth (n 5 2
webs). During the filling in activity, the spider walked under the
sheet rapidly forward, and sideways in an irregular pattern
(Fig. 3), while tapping actively with both legs I. We did not see Figure 4.—Viscid globule from the dome-shaped sheet of Tidarren
individual threads in all cases, but based on the spider’s behavior sisyphoides. The globule is on a pair of core fibers.
in video analyses, the spider did not attach her dragline to all
threads she came in contact with, since she walked several tangle (27 out of 30) before dropping to the dome-shaped sheet.
millimeters and frequently several centimeters without attaching The spider sensed the prey as soon as it contacted the upper
her dragline. During the dragline attachments, the spider tangle, first orienting inside her retreat (this was not possible to
displayed two different movements: in one, she held the dragline observe in all cases) and then moving to the area of the dome
with one leg IV, while ipsilateral legs III and IV grasped the sheet sheet beneath the struggling prey. There she pulled some
line, and brought it toward the spinnerets; in the other, the threads, turned a few degrees, and pulled other threads until
spider’s two legs IV grasped the sheet simultaneously on either the prey contacted the dome-shaped sheet. On one occasion, the
side of her spinnerets while her abdomen bent ventrally toward spider broke the threads of the dome-shaped sheet and climbed
the lines and no leg held the dragline. We clearly observed both up to attack the prey in the upper tangle. Prey that fell to the
types of attachment behaviors in the construction of both the dome-shaped sheet were generally constrained until the spider
dome-shaped and the horizontal sheets. arrived, but in a few cases, large, strong, struggling insects (e.g.,
Most spiders had constructed the scaffolding (14 out of 15) katydids) broke free from the upper tangle and dome-shaped
and part of the dome-shaped sheet by the end of the first night. sheet. These prey hit the horizontal sheet, but were not trapped
Only four spiders constructed a complete web during the first there long enough for the spider’s attack. Prey that were placed
night. By the end of the third night, all but one spider that directly on the upper face of the horizontal sheet (n 5 7) were
never constructed the horizontal sheet had complete webs. All not restrained long enough to allow the spider attack the prey.
spiders added more threads, primarily to the dome-shaped Attack behavior.—Attacks began by applying viscid threads
sheet and to the tangle above it in subsequent nights. Filling in on to the prey with both simultaneous and alternate
the dome-shaped sheet consumed most of the construction movements of legs IV. If the prey was dangerous (e.g.,
time of the spider (about 70%) on subsequent nights. katydids), viscid threads were applied from farther away than
Viscid balls.—Viscid globules were present on threads of to flies or moths. Wrapping continued until prey was
both the dome-shaped and the horizontal sheets in all webs immobilized, at which point it was bitten. In 83% of 72
examined (Fig. 4). Globules measured 58.5 6 30.8 3 52.0 6 spider-prey encounters, the spider retired to her retreat and
29.3 mm (n 5 20 globules, 5 webs) on dome-shaped sheet lines returned to the prey after the prey’s movements had subsided.
and 100.0 6 62.0 3 88.3 6 56.7 mm on lines in the horizontal When the prey was large, the spider cut it free from the dome-
sheet (n 5 6 globules, 2 webs). Their mean density was lower shaped sheet before continuing the wrapping attack as it hung
in the horizontal sheet (0.94 balls/mm, SD 5 0.62; 2 webs; on a few lines below the level of the dome. If prey’s movements
26 mm of thread sampled) than in the dome-shaped sheet (1.5 had not completely subsided when the spider returned from
balls/mm, SD 5 1.3; 4 webs; 22 mm of thread sampled). her retreat, the prey was wrapped and bitten again. Then it
Globules were hydrophilic and increased in size in a humid- was carried, dangling from one leg IV to near the retreat where
saturated environment. it was wrapped some more and attached to the threads near
Dissecting function of the web.—In nature, seven flies in at the mouth of the retreat.
least three different families, five treehoppers (Membracidae),
DISCUSSION
two beetles (one Scarabaeidae, one Chrysomelidae) and one
honey bee were found in webs (n5 22). Most prey that were The complex aerial-sheet web of T. sisyphoides seems to be
dropped on webs were retained for several seconds in the upper unusual in several respects among theridiids. Several other
310 THE JOURNAL OF ARACHNOLOGY
theridiids (e.g., Anelosimus spp., Chrosiothes portalensis, side of objects that likely make attachments more secure,
Achaearanea tesselata, A. disparata, A. japonica) also construct occurs also in A. tesselata and some orb-weaver araneoids
webs with horizontal or bowl shaped aerial-sheets (Darchen (Jörger & Eberhard 2006; Eberhard 1990b; Eberhard 2001).
1968; Eberhard 1972; Darchen & Ledoux 1978; Eberhard et al. Breaking and releasing threads is frequent during some phases
2008a), but never a dome-shaped sheet as in T. sisyphoides of the web construction of these two species, as well as in S.
(and also some webs of T. haemorrhoidale Eberhard et al. triangulosa (Benjamin & Zschokke 2002) and L. geometricus
2008a). The aerial sheets have most likely evolved indepen- (Eberhard et al. 2008b). This behavior may be at least partially
dently in these theridiid lineages, as indicated by a recent explained by an inability of theridiids to digest silk, but it is
phylogenetic study that showed an extremely high flexibility in also possible that loose threads might increase prey retention
web-building behaviors and high convergence in web features in the web (Kirchner 1986; Blackledge et al. 2008). Break and
among theridiids (Eberhard et al. 2008a). However, the dome- reel behavior was not observed in T. sisyphoides, though it
shaped sheet and the presence of a horizontal sheet connected occurs in A. tesselata (Jörger & Eberhard 2006) during
to the border of the dome-shaped sheet (Fig. 1) seem to be exploration, and in A. tepidariorum (W. Eberhard pers.
unique features of the Tidarren genus; a horizontal sheet comm.), and L. geometricus during gum foot line construction
connected to the dome-shaped sheet has only been found in T. (Eberhard et al. 2008b).
sisyphoides. The absence of similar elements in webs of other Sheet construction by T. sisyphoides also resembled that of
theridiid species (Agnarsson 2004; Eberhard et al. 2008a) A. tesselata. The spider walked under silk lines while
suggests that, at least, some elements of the T. sisyphoides’ web constructing the sheet, filling in different parts of the sheet
represent an independent and unique event in the evolution of in no apparent order (perhaps more detailed observations
webs in Theridiidae. might establish some pattern). Attachments of the dragline
Despite the unusual design of the webs of T. sisyphoides, there were similar in both species: the spider used either one or both
are several general behavioral patterns in the web construction legs IV to hold sheet threads when she attached her dragline
that resemble those behaviors of other theridiid species that have during filling in behavior. Both species filled in the sheet with
quite different webs. T. sisyphoides explored prior to initiating apparently erratic wandering movements, although they were
web construction, constructed its web only at night, constructed apparently more regular in T. sisyphoides. Both species often
a scaffold that supports the rest of the web, alternated returned to the retreat during filling-in behavior, presumably
construction of different sections of the web, held its dragline using lines previously laid in the near vicinity of the retreat.
with one leg IV, doubled lines during the scaffold construction, This behavior results in only a few lines converging at the
and added new threads and repaired the web over many mouth of the retreat, and explains the ability of the spider to
subsequent nights. These behavior patterns are similar to those orient inside the retreat toward the prey in the web before
of other species of Theridiidae: Latrodectus, Steatoda, Theridion, launching an attack (Barrantes & Weng 2006a; Jörger &
and Achaearaea (Szlep 1965; Eberhard 1982; Benjamin & Eberhard 2006). Having few threads converging at the retreat
Zschokke 2002, 2003; Jörger & Eberhard 2006; Barrantes & is also a feature of newly constructed webs of several
Weng 2007; Eberhard et al. 2008b), indicating that they are Latrodectus (Szlep 1965; Eberhard et al. 2008b).
widespread within theridiids. Similar behaviors occur in other Some general behaviors (e.g., construction of scaffolding,
spider families. For instance, holding the dragline with one leg expansion of web over time) are widely spread within
IV, alternating construction of different parts of the web, and theridiids. However, some other traits such as the presence
doubling threads has also been described for other Orbiculariae of an aerial sheet in the web have probably evolved
(Eberhard 1990b). Descending from the retreat (or near to it) independently several times within Theridiidae (Jörger &
along a pre-existing thread while putting out a new line, walking Eberhard 2006; Agnarsson 2004; Eberhard et al. 2008a), and
on the substrate, attaching this new line to the substrate, and other families (e.g., Linyphiidae, Pholcidae, and Synotaxidae-
then ascending by this new line to return to the retreat (or near Chileotaxus sans) possibly as a result of using similar habitats,
to it) during the scaffolding construction is another behavior capturing similar prey types (Wise 1982), and predation and
that has also been described for Steatoda triangulosa and A. parasitism pressure (Blackledge et al. 2003; Agnarsson 2004).
tepidariorum (Benjamin & Zschokke 2002, 2003). This order of The dome-shaped sheet and the tangle above it (upper
thread placement is similar to, though less stereotypical of, tangle) seem to function as the trapping section of the web.
radius construction in the Nephilidae and Uloboridae (Eberhard The upper tangle probably functions to knock down jumping
1982; Kuntner et al. 2008). However, further phylogenetic based and flying insects that are then restrained by viscid elements in
studies are necessary to determine whether these behaviors are the dome-shaped sheet, as indicated by the insect types found
homologous between Theridiidae and other Orbiculariae. in nature. The horizontal sheet at the bottom of the web seems
The detailed description of web-construction by A. tesselata to have little effect in prey retention; perhaps it serves as a
(Jörger & Eberhard 2006), allows us to further compare the barrier to reduce attacks of predators and parasitoids (Lubin
construction behavior between this species and T. sisyphoides. 1986; Blackledge et al. 2003). Viscid balls have not previously
Both species strengthened the lines holding up the retreat prior been reported in webs of species in this genus (Benjamin &
to initiating construction of the web. Securing the retreat first Zschokke 2003; Agnarsson 2004; Eberhard et al. 2008a). The
is likely due to the fact that in both species the spiders that viscid balls of gum foot lines and the viscous wrapping silk in
were observed had either egg sacs or spiderlings in their theridiids are apparently produced by the aggregate glands
retreats; in nature, these spiders first construct a web, and then (Kovoor 1977; Coddington 1989). However, until the origin of
collect a curled leaf or other plant debris to construct the the core axial fiber on which T. sisyphoides place the viscid
retreat. Attaching the anchor and scaffolding lines to the far balls is clearly established, it will be possible to determine
MADRIGAL-BRENES & BARRANTES—WEB OF TIDARREN SISYPHOIDES 311
whether these viscid threads are homologous to the gum foot Eberhard, W.G. 1981. The single line web of Phoroncidia studo Levi
lines or other sticky threads of other theridiid webs (Eberhard (Araneae: Theridiidae): a prey attractant? Journal of Arachnology
et al. 2008a). 9:229–232.
Eberhard, W.G. 1982. Behavioral characters for the higher classifi-
ACKNOWLEDGMENTS cation of orb-weaving spiders. Evolution 36:1067–1095.
Eberhard, W.G. 1990a. Function and phylogeny of spider webs.
We thank William Eberhard for his helpful comments on
Annual Review of Ecology and Systematics 21:341–372.
the manuscript and Emilia Triana for help feeding the spiders.
Eberhard, W.G. 1990b. Early stages of orb construction by
This study was supported by the Vicerrectorı́a de Investiga- Philoponella vicina, Leucauge mariana and Nephila clavipes
ción, Universidad de Costa Rica. (Araneae, Uloboridae and Tetragnathidae) and their phylogenetic
implications. Journal of Arachnology 18:205–234.
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