Caecosphaeroma Burgundum on:
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''Caecosphaeroma'' is a troglodytic
They measure from 2–20 mm long. As cave dwellers, they have lost their vision, but remain sensitive to light, which they shun. They are capable of
isopod
Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, an ...
genus in the family Sphaeromatidae
Sphaeromatidae (marine pillbug family) is a family of isopods, often encountered on rocky shores and in shelf waters in temperate zones. The family includes almost 100 genera and 619 known marine species (and about 65 in fresh water). Within the ...
found in cave
A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...
s of NE and SW France. The genus was split off from Monolistra
''Monolistra'' is a genus of isopod crustaceans in the family Sphaeromatidae. Its members are restricted to countries of the former Yugoslavia and neighbouring Italy. It contains the following subgenera and species, four of which are listed as ...
by Adrien Dollfus
Adrien Frédéric Jules Dollfus (21 March 1858, in Mulhouse-Dornach – 19 November 1921, in Paris) was a French carcinologist known for his work with terrestrial isopods, including crustaceans and trilobites.
Life and career
Adrien Dollfus was th ...
in 1896; in both genera, the female carries about 10 fertilized eggs in its external marsupium (brood pouch); they are white in ''Monolistra'' but bluish-green in ''Caecosphaeroma''. ''C. burgundum'' is the most studied species.
Description
They measure from 2–20 mm long. As cave dwellers, they have lost their vision, but remain sensitive to light, which they shun. They are capable of volvation
Volvation (from Latin ''volvere'' "roll", and the suffix ''-(a)tion''; sometimes called enrollment or conglobation), is a defensive behavior in certain animals, in which the animal rolls its own body into a ball, presenting only the hardest parts ...
(rolling themselves into a ball) to protect themselves, rest, or sleep. During copulation the male and female embrace takes the form of two concentric spheres.
Development
Larva remain in the marsupium about 12 months, and the animals continue growing for several years, reaching a final length of 10–20 mm.Evolution
The marine ancestors of ''Caecosphaeroma'' are believed to have migrated up the course of rivers and adapted to a subterranean environment that was relatively stable; meanwhile the marine environment of their ancestors changed, so ''Caecosphaeroma'' continued to differentiate as a separate lineage.Volvation in ''C. burgundum''
''C. burgundum'' has evolved in ways to improve its ability to curl into a ball. The mandibular palps and antennae are able retract into two deep grooves of the face, and the posterior margin of pleotelson (the last body segment fused with the "tail") provides greater mechanical support for the head. Evolution ofvolvation
Volvation (from Latin ''volvere'' "roll", and the suffix ''-(a)tion''; sometimes called enrollment or conglobation), is a defensive behavior in certain animals, in which the animal rolls its own body into a ball, presenting only the hardest parts ...
is seen in other subterranean isopods, but only ''C. burgundum'' is able to roll up into a hermetic sphere without any outward projections, and thus "approaches perfection in volvation". (Article has English abstract.)
References
External links
{{Portal, Arthropods Sphaeromatidae Cave crustaceans Fauna of France Isopod genera