Journal of Comparative Physiology B

, Volume 183, Issue 3, pp 323–332 | Cite as

Metabolic and water loss rates of two cryptic species in the African velvet worm genus Opisthopatus (Onychophora)

  • Christopher W. WeldonEmail author
  • Savel R. Daniels
  • Susana Clusella-Trullas
  • Steven L. Chown
Original Paper


Velvet worms (Onychophora) are characterised by a dearth of mechanisms to retain water, yet recently identified cryptic species are located in areas with seemingly different climates. Using flow-through respirometry, this study determined the metabolic, water loss and cuticular water loss rates of two cryptic species of Opisthopatus cinctipes s.l. from locations that differ in their current climate. When controlling for trial temperature and body mass, velvet worms from the drier and warmer site had significantly lower water loss rates than the wetter and cooler site. Mass-corrected metabolic rate and cuticular water loss did not differ significantly between the two sites. The scaling exponent for the relationship between log metabolic rate and log body mass for O. cinctipes s.l. declined with an increase in temperature from 5 to 15 °C. Females in the two cryptic Opisthopatus species had higher metabolic, water loss and cuticular water loss rates than males, which may represent the increased energetic demands of embryonic growth and development in these viviparous taxa.


Body mass Scaling exponent Sex differences Temperature Onychophora 



Springtails given to the velvet worms as food were kindly provided by Charlene Janion. Erika Nortje provided access to mealworm larvae and technical assistance. All meteorological data in this manuscript were provided by the South African Weather Service. SRD and SLC were funded by the National Research Foundation, South Africa, SCT was partially supported by a HOPE Project grant and Sub-Committee B from Stellenbosch University. Eastern Cape Parks provided permits to SRD to collect velvet worms. The constructive comments and suggestions of two anonymous referees contributed positively to the final form of the manuscript.

Supplementary material

360_2012_715_MOESM1_ESM.tiff (643 kb)
Online Resource 1. Standard metabolic rate of Opisthopatus cinctipes s.l. from two sites in the Eastern Cape, South Africa, at three test temperatures. A: 15 °C; B: 10 °C; C: 5 °C. Black diamonds: Katberg; grey circles: Zuurberg. (TIFF 642 kb)
360_2012_715_MOESM2_ESM.tiff (99 kb)
Online Resource 2. Cuticular water loss rate of Opisthopatus cinctipes s.l. from two sites in the Eastern Cape, South Africa, at three test temperatures. A: 15 °C; B: 10 °C; C: 5 °C. Black diamonds: Katberg; grey circles: Zuurberg (TIFF 98 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Christopher W. Weldon
    • 1
    • 3
    Email author
  • Savel R. Daniels
    • 2
  • Susana Clusella-Trullas
    • 1
  • Steven L. Chown
    • 1
    • 4
  1. 1.Centre for Invasion Biology, Department of Botany and ZoologyStellenbosch UniversityMatielandSouth Africa
  2. 2.Department of Botany and ZoologyStellenbosch UniversityMatielandSouth Africa
  3. 3.Department of Zoology and EntomologyUniversity of PretoriaPretoriaSouth Africa
  4. 4.School of Biological SciencesMonash UniversityMelbourneAustralia

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