26
Water Balance in Mediterranean Arthropods
Drought
~?) / I d
~/
Decreasing:
Lipids
Glycogene
Inaeasing:
Glycol
Sugars
Intracytoplasmic graiQs
with lipopolysaccharids
in the cells
Physiological
adaptations
Metabolic
adaptations
Cellular
adaptations
Decreasing:
Glycogene
Inaeasing:
Glycerol
Sugars
Concentration of
osmiophilous
polysaccharids and
lipids in epidermis
Fig. 2.6. Physiological, metabolic and cellular adaptations of collembDlans to cold and drought.
(Poinsot-Balaguer 1990)
lysed anhydrobiosis in the collembolan Subisotoma variabilis. Anhydrobiosis
is induced by progressive desiccation of the substrate, but other external signals and endogenous factors may also be involved (Poinsot-Balaguer 1988).
First, animals migrate downwards, remain motionless and lose body water.
Changes then occur in their external morphology involving the active contraction and folding of the cuticle and the extrusion of wax, which reduces
transpiration. During periods of anhydrobiosis, animals can survive extremely low moisture conditions for several months, and a lowering of the
supercooling point to -25 °C, occurs as well. With restored moisture conditions, external morphology revives rapidly and collembolans become active
within 1 h. Anhydrobiosis is independent of age and can be entered into
several times during the life of an individual.
Aside from morphological changes, Belgnaoui and Barra (1988) also
described changes in metabolism in the collembolan Folsomides angularis.
After 2 months in anhydrobiosis, glycogen which is used for the synthesis of
Water Balance in Mediterranean Arthropods
Drought
~?) / I d
~/
Decreasing:
Lipids
Glycogene
Inaeasing:
Glycol
Sugars
Intracytoplasmic graiQs
with lipopolysaccharids
in the cells
Physiological
adaptations
Metabolic
adaptations
Cellular
adaptations
Decreasing:
Glycogene
Inaeasing:
Glycerol
Sugars
Concentration of
osmiophilous
polysaccharids and
lipids in epidermis
Fig. 2.6. Physiological, metabolic and cellular adaptations of collembDlans to cold and drought.
(Poinsot-Balaguer 1990)
lysed anhydrobiosis in the collembolan Subisotoma variabilis. Anhydrobiosis
is induced by progressive desiccation of the substrate, but other external signals and endogenous factors may also be involved (Poinsot-Balaguer 1988).
First, animals migrate downwards, remain motionless and lose body water.
Changes then occur in their external morphology involving the active contraction and folding of the cuticle and the extrusion of wax, which reduces
transpiration. During periods of anhydrobiosis, animals can survive extremely low moisture conditions for several months, and a lowering of the
supercooling point to -25 °C, occurs as well. With restored moisture conditions, external morphology revives rapidly and collembolans become active
within 1 h. Anhydrobiosis is independent of age and can be entered into
several times during the life of an individual.
Aside from morphological changes, Belgnaoui and Barra (1988) also
described changes in metabolism in the collembolan Folsomides angularis.
After 2 months in anhydrobiosis, glycogen which is used for the synthesis of