Herbert W. Levi.
Predatory and Sexual Behaviour of the Spider Sicarius (Araneae: Sicariidae).
Psyche 74(4):320-330, 1967.

This article at Hindawi Publishing: https://doi.org/10.1155/1967/28091
CEC's scan of this article: http://psyche.entclub.org/pdf/74/74-320.pdf, 1708K
This landing page: http://psyche.entclub.org/74/74-320.html

The following unprocessed text is extracted automatically from the PDF file, and is likely to be both incomplete and full of errors. Please consult the PDF file for the complete article.

PREDATORY AND SEXUAL BEHAVIOR OF
THE SPIDER
SICARIUS (ARANEAE : SICARIIDAE)*
Museum of Comparative Zoology, Harvard University For a period of over 20 years, from 191 I to 1933 (Bonnet, 1945), Gerhardt published observations on the sexual behavior of spiders, describing sperm induction, charging the pedipalps with sperm, as well as mating. The observations (Gerhardt, 1924, 1927, 1930, 1933) concerned representatives of all available families with the hope of obtaining comparative data. Different groups of spiders have different methods of sperm induction and different mating positions. Gerhardt was more interested in the mechanical aspects of mating than in courtship behavior. A helpful summary (in English) of the observations of Gerhardt. Bristowe and others is provided bv Kaston (1948). Only in the last few years have there been some experimental studies, including observations on the copulatory behavior of spiders after removal of their palpi (Rovner, 1966, 1967). Surprisingly, courtship continued normally although both pedipalps had been am- putated in the penultimate instar and neither sperm induction nor copulation was oossible.
During sperm induction, the spider makes a web with silk from the posterior spinnerets. A small area in the web, a substrate, is prepared with silk from spinning glands in the epigastric area (Melchers, 1963; Alarples, 1967). On this substrate a drop of sperm is deposited. The sperm is drawn into a duct within the pedipalp of the spider, perhaps by resorption of a fluid previously secreted by the surrounding glands (Cooke, 1966). In some haplogyne spiders (which lack an epigynum, a plate with copulatory pores separate from gonopores), both pedi- palps are inserted into the drop simultaneously; in Orthognatha (the "tarantulas" of American parlance) and most other spiders, alter- nately. Some spiders attach the drop below the web and stand above while charging the pedipalps; others deposit the drop on the upper surface and reach around the edge to charge the pedipalps through the web. The pedipalps are recharged after mating. *I would like to thank Dr. J. A. L. Cooke, Oxford University, and Mr. W. Eberhard for suggestions, L. R. Levi and Mrs. R. Matthews for editing. The observations were supported in part by Public Health Service Research Grant AI-01944 from the National Institute of Allergy and Infectious Dis- eases.
Manuscript received by the editor December IS, 1967



================================================================================

19671 Levi - Behavior of Sicarius 321
There is an enormous literature on courtship, partially summarized by Kaestner ( 1965, and in press). The possible mating positions are summarized by Kaston (1948). In the Orthognatha and many hap- logynes, the male stands with his body at an angle to that of the female, or with his dorsum applied to her venter, the partners facing opposite directions. In others, mainly hunting spiders, the male mounts the back of the female, facing in the opposite direction. In many web spiders he crawls under the female, venter to venter, facing the same direction. In others the male and female position themselves venter to venter facing opposite directions. In some, the female lies on her side with the male over her. In most haplogynes both pedi- palps are inserted at the same time; in other than haplogynes only one is used or, more commonly, the pedipalps are alternated. Dabelow, in a recent paper (1958), described differences in mating position of different "races" of the haplogyne Sc~todes thoracica from the Mediterranean, Dalmatia and central Europe. The' female has sclerotized grooves on the venter of the abdomen which receive the jaws of the male during copulation. Females of the Mediter- ranean race took a vertical position with the male horizontal. In the central European race both tended to assume a vertical position facing the same direction. In the Dalmatian race the male crawled under the female and mated venter to venter. As no taxonomic revision of European Scytodes exists, it is difficult to interpret the results. The variation in mating position might reflect geographical variation or the "races" may actually represent separate species. Whatever the factors, apparently this behavior is not as conservative as formerly thought. A Scytodes sp. from Arizona was observed by W. Eberhard (unpublished) to take still another position. Its chelicerae did not bite into the sclerotized abdominal grooves at all during mating. One family not represented in any of these studies and never heretofore recorded is the Sicariidae, a small family of spiders mainly of the southern hemisphere, Africa and South America. Sicariids, as an adaptation to their mainly arid and hot desert habitat, bury themselves in sand (Reiskind, 1966) and sand grains from their surroundings adhere to their setae, giving the spiders the color of their background. Scytodes is often erroneously placed by European arach- nologists in the haplogyne family Sicariidae. Most European arach-
nologists are completely unaware of the nature of Sicmius, having seen only preserved specimens. Judging by the observations to follow, the families Scytodidae and Sicariidae, while related, are nevertheless distinct.




================================================================================

322 Psyche [December
A taxonomic revision of the family Sicariidae has never been made. Such a study would be time consuming and difficult - the holotypes of the numerous names would have to be consulted in various South American museums. The species in our cultures are thus labelled no. I (from Tucumhn Province, Argentina) and no. 2 (from Lima, Peru). Voucher specimens have been placed in the Museum of Com- parative Zoology. The life history observations recorded here come from culture no. I.
FEEDING
Sicarius is a powerful spider that feeds on passing insects, rapidly emerging from the sand when disturbed. The prey is not chewed but, like the prey of many spiders, apparently liquified inside its integu- ment and then sucked out. No use at all is made of silk in prey capture. Small prey (e.g. house flies, mealworms) are taken along when the spider digs itself into the sand, and are never left and picked up later.
However, a grasshopper I 1/2 times as long as Sicarius was bitten and left, to be attacked again shortly afterwards. When the prey was somewhat subdued the spider began feeding, changing the place of biting and turning the prey during the next five hours. The prey was then left during the evening, and the spider buried it- self; the next morning, the spider emerged and went straight to the grasshopper shell about 5 cm away, bit into it and fed for a while. Whether it fed during the night is not known. (It is doubtful that sicarild eyes produce a picture image.)
MATING
Of the contents of one egg case raised, four specimens matured: one female and three males. After two males matured in June 1967, they were "restless" and often were seen against the walls of their plastic container, rarely buried. On the 20th of July, 1967, one male was placed with a female, one with an immature male thought to be an adult female. They 'buried themselves after the disturbance. The male placed with the juvenile specimen showed no interest in it. The juvenile molted on 21 October 1967, and turned out to be a male.
The other male, however, surfaced after about two hours and walked about. Suddenly he stopped and began to dig with the front legs, thus exposing the posterior end of the abdomen of the female, who was facing the opposite direction. After the female was dug out or in part emerged from the sand (at about 15:3o), the male and female stood face to face, the fronts of their carapaces touching. The male gently felt the dorsal abdomen of the female with his long legs.



================================================================================

19671 Levi - Behavior of Sicarius 323
Fig t. Simriui sp. mating; each individual is about 18 mm in body length.




================================================================================

324 Psyche [December
Then with a sudden movement the male turned the female into mat- ing position, clamping her down with his legs (Fig. I), and both pedipalps were inserted immediately (at I 5 :35). The pedipalps 'wiggled" slightly. Once in a while the female made a slight motion (Fig. I ). After 18 minutes ( 15 :53) the animals suddenly separated, the female moved about 7 cm to the side and rapidly dug herself in. The male stood for about 30 seconds, then moved off about 20 cm and buried himself.
On 17 Set~ember 1967, at 20:00, the same male was placed with the same female again. He moved slowly about, but stopped when he touched the partly exposed abdomen of the female. Suddenly he pulled her out of the sand sideways; the female did not resist. The male went through the same motions described above. For a short
time before turning the female on her back the front ends of the male's and female's carapaces touched. The spiders separated 30 minutes after starting copulation, moved in opposite directions, but did not bury themselves (perhaps due to relative darkness). Unfor-
tunately no movie camera was available to record the sequence. SPERM INDUCTION
The night following the first mating, neither of the mated spiders appeared active. Both remained buried. At 22:30 the following night (2 I July 1967), I was surprised to find the male hanging in a web, for I had not seen any use of spinnerets or silk before. The web consisted of very coarse strands of unequal width, diagonally from the side to the lid of the container, attached below to a vertical card- board partition,
above by several threads to the screen lid. The threads, later examined under the microscope, consisted of at least 10 strands matted together into a ribbon, flat in places. The male was hanging head up (Fig. 2), and the alternate forward and back movements of his pedipalps suggested that this might be the sperm web. A minute later the spider slid down and both pedipalps touched a yellowish-white droplet at the junction of the silk threads (Fig. 3). Both pedipalps touched the droplet at the same time, but did not move at all. The lights were turned on without apparently disturbing the spider (previous observations had been made with a dim flash- light).
An attempt to lift the lid (at 22:45), with the hope of photographing, however, disturbed the silk threads. The spider jumped down onto the sand and buried himself. The lack of threads with other males suggests that the web was destroyed and eaten after use.




================================================================================

Levi- Behavior of Sicarius
Fig. 2.
Male depositing sperm on sperm web.
LIFE SPAN
From a newly hatched eggcase given to me by Dr. W. K. Wey- rauch in February 1965 in Tucumin, we reared two males and one female that molted to maturity during June 1967 and one male that matured in October 1967. The individuals took more than two years to mature.
Individuals of species 2 from Lima, Peru, were I 1/2 years old and less than half grown in August 1967. An adult in- dividual collected on 2 April
1965 (under a log in pasture near
Santiago del Estero) appeared moribund in July 1967; it had not fed for some time, no longer buried itself, and looked emaciated. After placing it in alcohol, I discovered it was a male. (Male sicariids differ from females by having longer legs and by modifications of the pedipalps that are not readily apparent). As far as we know, the
individual had never molted, had lived at least two years beyond reaching maturity, and was profbably at least four years old. After killing the male, we discovered that its container had become moldy, a condition that would be injurious to most spiders; thus it may have been moribund not from old age, but from poor laboratory conditions. DISCUSSION
Although related, sicariids are very different from scytodid spiders. While the slow scytodids overpower their prey by spitting a viscid, entangling substance, the sicariids are strong, fast moving; predators



================================================================================

Psyche
[December
Fig. 3.
Male taking up sperm into pedipalps.
that overpower their prey with force and poison. Both sicariids and loxoscelids lack the adaptations of scytodids for their unusual method of prey capture: the high-domed carapace containing the glands used for spitting, and the short, stout fangs with the aperture of the gland duct at their midpoint.
(The Loxoscelidae are also at times placed in the Sicariidae, but probably with more reason than the Scytodidae.) The sicariids courtship act of digging the female out of the sand is probably unique among spiders, but the mating position is similar to that of scytodids, a group in which there is some variation (see above). As in other haplogyne spiders (but unlike orthognath "tar- antulas"), both pedipalps are inserted into the gonopore at the same time.
Another habit shared with other haplogyne spiders, but not with orthognath "tarantulas", is that both pedipalps are inserted simulta- neously into the sperm drop during sperm induction. An exception is the haplogyne dysderid, Harpactes rubicundus, which uses the method exhibited by most spiders, continuously alternating the pedi-



================================================================================

19671 Levi - Behavior of Sicarius 327
palps for sperm filling. Members of the orb weaver genus Tetra- gnatha use the haplogyne method of sperm induction (Gerhardt, 1927), although the absence of an epigynum in Tetragnatha is be- lieved secondary. Filistata, though it lacks an epigynum, is considered (there abides a controversy) to belong to a separate line of evolution because of the presence of a cribellurn. The Filistata male alternates the pedipalps in mating and in sperm induction, as do the orthognaths (Gerhardt, 1930).
There is little literature on the significance of longevity of spiders. But it is striking that spiders with genitalia considered primitive are long lived, those with more typical genitalia are short lived. A short life span of one or two seasons and rapid succession of generations must be of selective advantage, as it is a charateristic of the most suc- cessful groups of spiders. Selective advantages might be larger num- bers of progeny, increased number of generations, and ability to colonize new situations, especially areas with short seasons, etc. Table I summarizes the available data on longevity of spider species with simple genitalia.
Primitive groups of hypochilid spider,^, however, are short lived. Adult Hypochilus gertschi disappear in the fall, adult females re- appearing in July. Probably it takes two years to mature (W. Shear, in letter). During an autumn visit to Chile (March, 1965), only juveniles of Thaida peculiaris (=Austrochilus manni) were found, no adults.
Adult Orthoganatha (e.g. Theraphosidae) molt once or twice a year during most of their long lives, except during the last year or two. Haplogyne spiders do not molt after reaching maturity. In molting, presumably, spiders shed also the lining of the seminal re- ceptacles and with it any stored sperm. Thus, it is rare for a captive theraphosid to produce an egg sac unless the animal is a recent captive. In contrast, some haplogyne females even after years of captivity may still produce fertile egg sacs from previous matings. Another specialization of scytodids that separates the family from other groups should be pointed out.
On the venter behind the gono-
pore the female has sclerotized grooves into which the fangs of the male are usually inserted to hold the female during mating; this structure is not present in sicariids or loxoscelids. Perhaps these grooves represent a preadaptation toward the evolution of an epigy- num (the plate bearing separate copulatory pores which lies in front of the gonopores) present in most higher spiders.



================================================================================

male life span
total life span molt as
of female 1 adults
time to
maturity
ca. 3 yr.
beyond maturity
to 20 yr. 1 9 9 yes
Theraphosidae
up to I yr.
2 + yr.
Sicar.iidael
Loxoscelidae
A+ vr. I no
I -2 + yr. (laetaj3
2 I /2 yr. (re~lusa)~ I
4-6 yr. (laeta)^ I
max. I yr.
1-1 1/2 yr.
?
I + yr. beyond 1 no
maturity
I
? 4+ yr.
no
4-5 Yr. -1 no
2-3 yr.
I 1/2 yr.
less than
I yr.
at most I 1/2 yr.
usually die
after mating
- -- -
at most I
season after
Most higher
spiders and
most cribellates
cribellate
Hypochilidae7
maturity
2-3 months
? 2 yr.
die after
ma,ting
die after
cribellate
Filistatidae8
? 1-2 yr.
mating
Table I.
Length of life of
'personal observation
'Hite, 1966
spiders considered "primitive" on basis of their simple genitalia. comm. Mrs. F. Coyle, A. Spielman, R. E. Wheeler from colonies kept at Cambridge, Mass. Dabelow, 1958, on Scytodes thoracica
pers. comm. W. Eberhard
'Cooke, 1965a, b, on Dysdera crocata.
~ers. comm. W. Shear
'Gerhardt, 1930; Lowrie, 1965




================================================================================

19671 Levi- Behavior of Sicarius 329
In the Pholcidae, this same structure, a swollen area held by the male with his chelicerae, is in front of the gonopores in place of the epigynum of other spiders. However, as indicated by this genital structure of the female and the unusual pedipalp structure of tlhe male, Pholcidae are not closely related to other spiders. Further evi- dence for this comes from the method of sperm induction, quite dif- ferent from that of any other spiders: the sperm drop is taken into the mouth aided by the third legs and from there to the palps. As in other haplogyne spiders, both ~edipalps are inserted simultaneously into the female gonopore (Gerhardt, I 927). A unique, as yet unmentioned, behavioral character of sicariids is the eggsac. Made of sand grains, it resembles a mud-dauber nest rather than a spider eggsac (Levi and Levi, 1968, p. 28). The method of construction is unknown. Scytodids carry their eggs in a loose sac; loxoscelids attach their eggs, wrapped in very few threads, in their webs, as do plectreurids. Dysderids keep their eggs at the inner end of the tube with no silk around the eggs (Ariadna and Dysdera). Diguetid eggs are contained in strong silk sacs within a strong silken tube.
SUMMARY
Sicarius feeds by overpowering passing insects. No use is made of silk in feeding; the prey seems to be slowed down by poison. The male begins courtship 'by digging the female out of the sand and stroking her. The mating position was observed (Fig. I ) ; both pedi- palps were inserted simultaneously. A female will mate repeatedly. In recharging the pedipalps, both were dipped simultaneously into the sperm drop on a specially made web and held in the drop without visible movement. In their long life span sicariids resemble other haplogyne spiders (although there are some exceptions). In its be-
havior, Sicarius resembles Loxosceles more than Scytodes. Construc-
tion of the unusual eggsac of Sicarius has not been observed. REFERENCES CITED
BONNET, P.
1945. Bibliographia Araneorum, Toulouse, vol. 1. COOKE, J. A. L.
1965a. Beobachtungen an der Spinnengattung Dysdera. Natur Museum 95 : 179-184.
1965b. A contribution to the biology of the British spiders belonging to the genus Dysdera. Oikos 16: 20-25.
1966. Genitalia in Dysdera crocata. Senckenbergiana Biol. 47: 35-43. DABELOW, S.
1958. Zur Biologie der Leimschleuderspinne Scytodes thoracica (La- treille). 2001. Jahrb. Abt. Syst. 86: 85-162.



================================================================================

Psyche
[December
GERHARDT, U.
1924. Neue Studien zur Sexualbiologie und zur Bedeutung des sexuellen GrOssendimorphisrnus der Spinnen. 2. Morphol. okol. Tiere 1: 507-538.
1927. Neue biologische Untersuchungen an einheimischen und ausland- ischen Spinnen. Ibid. 8: 96-186.
1930. Biologische Untersuchungen an siidfranzosischen Spinnen. Ibid. 19: 185-471.
1933. Neue Untersuchungen zur Sexualbiologie der Spinnen. Ibid. 27: 1-75.
HITE, J. M. et al.
1966. Biology of the Brown Recluse Spider. Bull. Agr. Ex$. Sta. Univ. Arkansas 71 1 : 1-26.
KAESTNER, A.
1965. Lehrbuch der ~peziellen Zoologic, G. Fischer, Jena, 2nd edit. vol. 1.
KAESTNER, A., translated and adapted by H. W. LEVI and L. R. LEVI. (in press). Invertebrate Zoology vol. 2. Arthropod Relatives, Cheli- cerates and Myriapods. Wiley, Interscience, New York. KASTON, B. J.
1948. Spiders of Connecticut. Bull. State Geol. Nut. Hist. Surv. Hart- ford 70 : 1-874.
LEVI, H. W. and L. R. LEVI
1968. Spiders and their Kin. The Golden Press, New York. LOWRIE, D.
1966. Longevity record of a spider of the genus Filistata. Bull. South,
California Acad. Sci. 65 : 249-250.
MARPLES, B. J.
1967. The spinnerets and epiandrous glands of spiders. J. Linnean Soc. London (2001.) 46: 209-222.
MELCHERS, M.
1963. Zur Biologie der Vogelspinnen. 7. Morphol. 0kol. Tiere 53: 517-536.
REISKIND, JONATHAN
1966. Self-burying behavior in the genus Sicarius (Araneae, Sicariidae). Psyche 72: 218-224.
ROVNER, J. S.
1966. Courtship in spiders without prior sperm induction. Science 152 :
542-544.
1967. Copulation and sperm induction by normal and palpless male linyphiid spiders. Ibid. 157: 835.




================================================================================