section contributed by Anja E. Klann
Ernst-Moritz-Arndt-University Greifswald, Germany
maintenance of an equal body temperature without an extreme water loss is the
main problem facing all desert arthropods (Cloudsley-Thompson,
1991). Solifuges seem to be unusually tolerant of heat and drought compared to
other desert arachnids or insects. For example, Galeodes granti is able
to survive 49°C with a relative humidity below 10% for 24h (Cloudsley-Thompson,
1962). Punzo (1994) studied the
combined effects of temperature and relative humidity along an altitudinal
gradient in specimens of Eremobates palpisetulosus. Due to the sometimes
unexpected high differences in temperature between favorable microenvironments
(such as burrows and other kinds of retreats) and the soil surface (Cloudsley-Thompson, 1956), nocturnal solifugid species (and
other desert arthropods as well) usually retreat to such microenvironments
during the daytime, enabling them to maintain thermal homeostasis to a certain
Even though Cloudsley-Thompson (1961) showed that Galeodes arabs
C. L. Koch has a low water loss by transpiration, and thus a high capacity for
water conservation, it occasionally drank in captivity by chewing on wet acacia
leaves with its chelicerae. In nature, however, solifuges seem to obtain
sufficient moisture from the body fluids of their prey.
Various authors have described the relatively rapid sprint
speeds of many solifugid species (e. g.,
Heymons, 1902), which requires an efficient respiratory system. Solifuges
are characterized by an apomorphic, highly complex tracheal system with
spiracles that allows for direct O2 provision and CO2
elimination. Lighton and Fielden
(1996) examined the gas exchange in Eremcosta titania and Eremobates
sp. (Eremobatidae) from the Mojave desert of California and revealed that
they utilize a discontinuous gas exchange (DGC), which is almost identical to
that of insects. The DGC in solifuges can be divided into three distinct
phases. The C phase is characterized by closed spiracles, and prevents almost
any external gas exchange. Endotracheal hypoxia probably causes the termination
of the C phase, which is followed by a largely diffusive phase characterized by
tissue-level O2 uptake. The accumulation of CO2 in the
hemolymph resulting from the sealed C phase initiates the O phase when reaching
the hypercapnic set-point.
summarized the few physiological studies published so far on the respiratory
system, temperature and moisture stress, and neurochemistry. The physiology of
solifuges is only scarcely studied and therefore merits much more attention.
Cloudsley-Thompson, J.L. 1956. Studies in diurnal rhythms. - VI. Bioclimatic observations in Tunisia
and their significance in relation to the physiology of the fauna, especially
woodlice, centipedes, scorpions and beetles. Annals and Magazine of Natural
History (12) 9: 305-329.
1961b. Some aspects of the physiology and behavior of Galeodes arabs.
applicata, 4: 257-263.
Cloudsley-Thompson, J.L. 1962. Lethal temperatures of some desert arthropods and the mechanism of
Entomologia Experimentalis et Applicata 5: 270-280.
J.L. 1991. Ecophysiology of desert arthoropods and reptiles. Springer-Verlag:
R. 1902. Biologische Beobachtungen an asiatischen Solifugen, nebst Beiträgen zur
Abhandlungen der Preussischen
Akademie der Wissenschafen zu Berlin, 1902: Anhang 1 [pages?].
Lighton, J.R.B. and Feldon,
L.J. 1996. Gas
exchange in wind spiders (Arachnida, Solphugidae [sic]): independent
of convergent control strategies in solphugids [sic] and insects. Journal of
Insect Physiology 42: 347-
994c. Intraspecific variation in response to temperature and moisture in
Eremobates palpisetulosus Fichter
(Solpugida, Eremobatidae) along an
Bulletin of the British
Arachnological Society, 9: 256-
Punzo, F. 1998. The Biology of Camel-spiders (Arachnida,
Solifugae). Kluwer Academic Publishers, Boston.