Table Of Content1991. TheJournal ofArachnology 19:97-101
MOTHER OFFSPRING FOOD TRANSFER IN
COELOTES TERRESTRIS {ARANEAE, AGELENIDAE)
Jean-Luc Gundermann, Andre Horel and Chantal Roland: Laboratoire de Biologie du
Comportement, Unite associee au CNRS, URA 1293, Universite de Nancy I, BP 239,
54506 Vandoeuvre-Les-Nancy Cedex, France
Abstract. Threedifferentmodesofmaternalfoodsupplyhavebeenreportedinthesub-
social agelenid species Coelotes terrestris: prey provisioning, consumption ofthe mother’s
body,andregurgitationofnutritivefluids.Althoughthefirsttwomodesarewelldocumented,
the latteris not fully assessed.
Bycomparing—intheabsenceofanyprey—theweightvariationsinspiderlingseitherleft
with their mother or isolated, and by simultaneously comparing the weight variations of
mothers,eitherisolatedorleftwithinthegroupofspiderlings,itwaspossibletoseeevidence
ofa significant and long-lasting food transfer from the mother to her progeny. This food
transfer probably explains the high level of survivorship and reduction of cannibalism
showed bybroods left with theirmothers.
Close observation provided no direct evidence ofmouth to mouth transfer. Rather, the
food transfer appears to involve the production and emission of miniature eggs by the
mother when in presence ofspiderlings, a phenomenon which to date seems not to have
been noted amongspiders.
Providing offspring with food is one of the social species Coelotes terrestris (Wider) (KTafft
most important features ofparental care, in that etal. 1986),inparticularthethreemodesoffood
itsparestheyoungthemanyrisksrelatedtofood supplypreviouslyreportedbyTretzel(1961):prey
supply (Wilson 1971). In spiders, food may be provisioning (Gundermann et al. 1988), moth-
provided by the mother in various forms. The er’s consumption (Gundermann 1989) and re-
yolk contained in the egg ensures the beginning gurgitation. This last mode is poorlydocument-
of the spiderling’s development during its life ed. Tretzel (1961) referred, for this species, to
inside the egg sac and the few days following its only one definite observation, and our own ob-
emergence(Foelix 1982).Thissupplycanbesup- servationsarerareanddubious. Suchasituation
plemented,inseveralspecies,byoophagyofnon- could be explained, either by the actual scarcity
hatched eggs inside the egg sac (Schick 1972; ofthe phenomenon—which would then lead to
Valerio 1974). In a certain number of species, question itsfunctional significance—orby itslo-
themotherprovidesfoodtoagreaterextent. Her calizationduringthenocturnalphasemakingthe
body maybe a usual, oroccasional, resource for observationsdifficult. Thus, the veryfirststepof
herprogeny (Bristowe 1958; Cloudsley-Thomp- the study, as exposed in the present paper, was
son 1955;Kullmann 1972;Seibt&Wickler 1987; todemonstratetheexistenceofasignificantfood
Tahiri et al. 1989). Provisioning has also been transferfrom the motherto heroffspring, andto
reported, either in the form ofprey items sub- try and find out its nature.
dued by the mother and carried to the brood MATERIALS AND METHODS
(Brach 1976; Hirschberg 1969; Gundermann et
al. 1988; Tretzel 1961) or offluids regurgitated The funnel-web agelenid Coelotes terrestris is
to the spiderlings (Locket 1926; Kullmann & aterricolousspidercommonin Europeanwood-
Zimmermann 1974). These fluids may be the lands. The female weaves a silken tube under
result of the partial digestion of the prey, or stones, bark ofdead logs, etc. From a lenticular
sometimes, a production ofthe mother’s diges- egg sac, 40 to 60 spiderlings emerge, stay in a
tive tract (Nawabi, cited by Collatz 1987). groupinsidethetubewiththeirmotherforabout
We are currently studying the mother-young onemonth,andthendisperseandleadasolitary
interactions related to food in a European sub- life (Tretzel 1961; Gundermann 1989).
97
98 THEJOURNALOFARACHNOLOGY
Brood's size aspiration using a pipette. The brood’s weight
wasestimatedbymultiplyingtheindividualmean
weight(givenbythesampling)bythe numberof
spiderlings still alive. At the end ofthe experi-
ment some broods’ sizes fell below 10 individ-
uals; in this case, ofcourse, the totality of the
brood was weighed.
2—Thesecondexperimentwasdesignedtoget
furtherinformationbytryingtoenhancemother-
young interactions. Ten groups ofthree day old
spiderlingswereseparatedfromtheirmothersfor
24 h without any food. The subsequent reunion
ofthe mother with their young were thoroughly
observed and videorecorded.
RESULTS
Figure 1.—Weekly variations of the broods’ sizes
(median,quartiles). Open squares = treatmentA{N= 25.S5u)rvivorship.—Orphaned broods (treatment
17): orphaned brood; solid squares = treatment B (N A) showed a very poor survivorship: at the end
= 17):broodleftwithmother.E.:Emergenceday.Mann- 8o8f.t5h)e experiment, the median rate ofsurvivor-
Whitney [/-test: ns, non significant; *** P < 0.001. ship(numberofspiderlingsstillalive/initialsize
ofthebrood x 100)fellto 12.5%(quartiles: 6.3-
In contrast, survivorship stayed high in
.
Inthepresentstudy,fieldinseminatedfemales treatmentB(medianrate:81.8%,quartiles:76.6-
were collected, then reared in the laboratory in Actuallythedifferencebetweenthebroods’
.
plasticboxes(15 x 9 x 7.5cm)withtransparent sizes ofthe two treatments was significant from
sides and a bottom covered with a mixture of the end of week 1 on (Fig. 1) (Mann-Whitney
sand and peat which was regularly moistened. t/-test, P < 0.001). Direct observations and the
The rearing boxes were kept in a closed room, fact that no dead bodies could be found in the
atatemperatureof21 °C(±2°),fluorescentlights vials lead to attribute this differential mortality
providing a light ofabout 100 lux (12 L/12 D). to a high incidence of cannibalism within or-
Two experiments were designed: phaned broods.
—
1 Inthefirstexperiment,itwashypothesized Weights’ variations.-Statistical analysis
that ifa food transferdid exist from the mother showed no significant difference between treat-
to her young, spiderlings left with their mother mentsAand B, onemergenceday, foreitherthe
shouldpresenthigherweightsthanorphanedspi- broods’ as well as the mothers’ weight (Mann-
derlings, while mothers left with their young Whitney U-test, ns).
shouldpresentlowerweightsthanisolatedmoth- From the end of week 1 on, the estimated
ers. weightsofthebroodsleftwiththeirmotherswere
The experiment started from the broods’ significantly higher than those ofthe orphaned
emergence (most of them occurred within 2 broods(Fig. 2a). Theanalysisofweights’weekly
weeks)andlasted4weeks.Throughoutthattime, variationswithineachtreatment(Table 1)shows
all the spiders were deprived ofprey. Egg sacs that, while orphaned broods’ weights (treatment
were randomly assigned to one of two treat- A) decreased (Wilcoxon matched-pairs signed-
ments: rank test: P < 0.002 for weeks 2 and 3; P <
—Treatment A (N = 17): mothers and young 0.001 for week 4), weights of broods left with
separated; their mothers (treatment B) varied in the op-
—Treatment B {N = 17): mothers left with posite direction (Wilcoxon test: P < 0.002 for
their young. weeks 1 and 2, ns forweek 3, P < 0.02 forweek
Mothers and broods were weighed, first just 4).
after emergence, then at the end ofeach week. The decrease in weight observed in treatment
In order to minimize disturbance ofthe brood, Acanbeaccountedforbybasalmetabolismand,
each weighing was limited to a sample of 10 probably,bylossesofmaterialandenergybrought
spiderlingscollected,asrandomlyaspossible,by about by high intrabrood cannibalism. On the
GUNDERMANN ETAL.-MATERNALFOODTRANSFER 99
Broods weight (mg) otherhand the lowlevel ofcannibalism intreat-
ment B cannot explain the increase in weight
observed in this treatment. Rather, the increase
suggeststhatsomesortoffoodisprovidedtothe
young by their mother.
Thisisconfirmedbythestudyofthemothers’
weightvariations(Fig. 2b). Fromtheendofweek
2, treatment B motherswere significantlylighter
A
than treatment mothers. Furthermore, the
comparison of the weekly losses in weight be-
tween treatment A and treatment B (Table 2)
shows that, when left with their broods, the
motherssufferedsignificantlymoresevereweight
decrease than when isolated.
Modes of mother-young food transfer.—The
Mother’s weight(mg) maintenance ofweight gain in broods left with
theirmothersoverfourweeksstronglysuggested
thatthefoodstransfershouldbearelativelylong-
lasting phenomenon. It was, thus, very unlikely
toconsistofmere regurgitation offluidsextract-
ed from the prey eaten bythe motherbefore the
beginningoftheexperiment.Thetransferredfood
should,then, beproducedbythemotherherself
Close examination of rearing boxes, using a
stereomicroscope, showed, at times, spiderlings
eating substances deposited on the web. These
substancesconsistedofeitherclearyellowdrops
ofliquid, or brownish compact clusters ofmore
or less discernible eggs. The egg sizes varied
greatly, but were always smaller (0.3-0.5 mm)
than the normal ones (0.7-1 mm). Some ofthe
Weeks
egg-clusterswerecoveredwithathinlayerofsilk,
qpuhaFaritngieluderse)b.r2.oO—opdWe;enesoksllqiudyasrwqeeusiagr=hetstvr=aeraittarmteeianottnmseAinnt(mNBg=((Am1e7=)d:i1ao7nr),-: soibmsTiehlreavrisntegoctothnheedpieonxstpseierbrnlaielmmelnoattyehwrearos-fyatohiuemneegdggfaotsoaddcistr.reacntsl-y
brood left with mother. E.: Emergence day. Mann-
WwehiigthnteyvarDi-taetsito:ns*;Pb<=0M.0ot1h;e*r**’sPw<ei0g.h0t0v1a.raia=tiBornoso.d’s tfehre.irAyctouuanlglya,ftetrhea2r4e-uhnisoenparoafttihoendmiodtnhoetrsindwiutche
any special reactions other than an intensive
weaving activity ofthe mothers, except in one
group inwhich theyoung, unliketheothers, dis-
Table 1.—Variationsofthebroods’medianweightsperweek,inmg(range),withineachtreatment.Treatment
A {N= 17): orphaned brood; treatment B (V= 17): brood left with mother. Wilcoxon matched-pairs signed-
rank test.
Treatment Week 1 Week 2 Week 3 Week4
TreatmentA -2.2 -11.9 -8.6 -2.8
Mothers isolated (-47.3; +21.9) (-32.7; +12.3) (-29.2; +3.5) (-23.4; +1.0)
Pvalue 2-tailed ns <0.002 <0.002 <0.001
Treatment B +19.2 +18.9 +7.0 +5.3
Motherswith broods (-6.7; +71.9) (-4.3; +72.1) (-25.4; +38.3) (-9.6; +31.6)
Pvalue 2-tailed <0.002 <0.002 ns (0.02)
100 THEJOURNALOFARACHNOLOGY
Table 2.—Mothers’ median weight losses perweek, in mg (range). Treatment A {N= 17): motherseparated
from brood; treatment B (A= 17): mother left with brood. Comparison treatment A vs. treatment B foreach
week: Mann-Whitney [/-test.
Treatment Week 1 Week 2 Week 3 Week 4
Treatment A -6.8 -4.7 -1.8 -2.5
T 1
Mothers isolated (-3.4; -10.6) (0.9; -8.3) (-0.3; -4.5) oo
Treatment B -21.3 -24.1 -11.5 -6.0
Mothers with broods (-5.9; -36.8) (-15.0; -26.6) (-7.0; -18.2) (-3.7; -10.1)
Pvalue 2-tailed <0.02 <0.001 <0.001 <0.05
playeda high level ofactivityand interactedfre- that food transfer could also occur in normally
quently with their mother. fed groups.
In this group, from the beginning, a few spi- Furtherinvestigationsarealsorequiredtofind
derlings followed their mother in her numerous out the mechanisms involvedin the process. To
movements and made attempts to come into what extent is ovarian production continuous?
contact with her, mainly in the direction ofher Isovarianphysiologyinfluencedbythepresence
hind-legsandopisthosoma(oneofthemwaseven ofthe brood? Does tactile (orother) stimulation
observed hanging from a spinneret). About 2 h ofthemotherbythespiderlingsreleasetheemis-
30 min after the reunion, the first emission of sion of ovarian substance, as suggested by our
substances took place with two more emissions observations?
being recorded within the following 10 min. As Asfarasweknow,thismodeofmaternalfeed-
soon as the drops of substance were deposited ing has never been previously reported in spi-
on the substratum they immediately attracted ders, but can be related to a somewhat similar
groups of two or three spiderlings. During the phenomenon described in the cricket Anuw-
last emission the orientation of the mother’s gryllusmuticus(West&Alexander 1963). Inthis
opisthosoma made it possible to clearly observe sub-social insect, after interactions between the
the progressive exuding of substance from the nymphs and their mother (recalling those ob-
vaginal opening. A spiderling, which had suc- served in Coelotes terrestris), the nymphs are
ceeded in climbingon to the opisthosoma, came provided with miniature eggs, that the authors
to the vaginal opening, seized the small ball of liken to the trophic eggs of ants (Brian 1953;
substance and eventually took it away. Wilson 1971). Actually, another mode of ma-
ternal feeding, not unlike what is here reported
CONCLUSION
in Coelotesterrestris, hasrecentlybeen observed
In Coelotes (errestris food is actually trans- in our laboratory (Tahiri et al. 1989). In two
ferred from the motherto heryoung. Thistrans- speciesofthegenusAmaurobius,A.feroxandA.
fer occurs when no prey are available, even for fenestralis, about 3 days after the emergence of
several weeks, thus indicating that food is pro- the offsprings, the mother lays an egg mass de-
duced by the mother herself. Even though the prived ofany silken envelope which is imme-
digestive tract can not be definitely ruled out as diately eaten by the spiderlings. This egg-laying
a site of production, the ovaries appear to be appears to be systematic and to represent the
playingamajorrolebyproducingminiaturetro- onlysourceoffood fortheyoungduringthefirst
phic eggs. Observations showed that these eggs tenpost-emergencedays. Thesefindings,togeth-
are particularly attractive to the young and rap- erwiththoseofspiderlingsfeedingoneggsinside
idly eaten. This mightexplain why they had not the egg sac (Schick 1972; Valerio 1974), suggest
been noticed before. thateggcannibalismcouldplayasignificantrole
Such a transfer of food is likely to enhance inthereproductivestrategiesofmanyspiderspe-
survivorship of young during food shortage in cies (see Polis 1981).
field conditions, at the expense ofthe mother’s ACKNOWLEDGMENTS
own survivorship. But the adaptive significance
ofthisphenomenonremainstobemoreprecisely We express our thanks to H. Gouth, D. Assi
assessed; some incidental observations suggest and D. Moncotel for their assistance in this re-
GUNDERMANNET AL.-MATERNALFOODTRANSFER 101
search. We are grateful to A. L. Rypstra and G. gitationfiitterungenals Bestandteil fur Brutfiirsorge
W. Uetz for their criticism and advice on the bei Haubennetz und Rohrenspinnen (Araneae,
manuscript. TheridiidaeundEresidae). Proc.6’"Intern.Arachn.
Cong., pp. 120-124.
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