Geophilomorph centipedes and the littoral habitat - Books and ...

Body fl uid regulation
A.D. Barber / Terrestrial Arthropod Reviews 4 (2011) 17–39 23
Figure 3. Stigmatogaster subterranea (Shaw, 1789) to show the body shape of a geophilomorph with a
distinct transition. Although normally a terrestrial species, this specimen was actually found under a stone
on estuarine mud, River Lynher, Cornwall, England.
As a legacy of their original marine origin myriapods have body fl uid concentrations
comparable to that of crustaceans (Little, 1990 ). For the two marine species studied by
Binyon and Lewis ( 1963 ), Strigamia maritima has a body fl uid OP of 462 mOsm.kg -
and a Na + level 274 mM.l -1 and Hydroschendyla submarina 498 mOsm.kg - and 283
mM.l -1 which are only slightly higher than the terrestrial Stigmatogaster subterranea
(Shaw, 1789) with 438 mOsm.kg - and 205 mM.l -1 although higher than those of the
lithobiomorph Lithobius forfi catus at 370 mOsm.kg - and 190 mM.l -1 (Little, 1983 ).
Th ese levels are about half or slightly less than that of full seawater so that such littoral
animals will still need to have mechanisms for regulating body fl uid volume e.g.
removal of excess ions by some mechanism. Alternatively, they will need be able to
tolerate changes of body fl uid concentration.
For terrestrial centipedes with their incomplete waterproofi ng / limited spiracular
closing mechanisms, dry air poses a threat of desiccation (as would seawater). Damp
environments which they normally tend to inhabit will pose the opposite threat of
osmotic water uptake which seems to be dealt with by removal of water in the gut and
retention of ions. It is possible that the coxal glands may, in some way be involved in
transporting (Little, 1983 ); see also the review of these in Rosenberg ( 2009 ).