Skip Navigation
  • UC Riverside
  • College of Natural and Agricultural Sciences


Emeritus Professor of Biology
Office 1111 Biological Sciences Building
Phone (951) 827-4682


Ph.D., University of California, Santa Barbara, 1966

Research in this lab has included several aspects of scorpion biology (ecology, population dynamics, behavior, physiology) summarized in the reviews cited below.  Any of this work can be extended, depending upon student interest, but present emphasis is on development, comparing organogenesis and viviparity among diverse species.  The intent is to relate scorpion ontogeny to their biogeography and fossil record and thereby gain a better understanding of the evolution of these survivors of the Paleozoic era.

Scorpions have an unusual integumentary layer (hyaline exocuticle) with a protein which fluoresces in ultraviolet light.  This makes these animals unusually accessible for study in the field as well as laboratory.  The hyaline layer in scorpions has also resulted in a preservational bias among other arthropods.  We thus have some fossils, the earliest from the Silurian period about 430 million years ago.  Those ancient scorpions (aquatic, more than 50 families) reached nearly a meter in length.  All disappeared (Devonian/Carboniferous), possibly from vulnerability during molt and from piscine or other predation on eggs, juveniles and/or adults.  The scorpion survivors are small, cryptic, terrestrial forms (9-15 families) with booklungs and viviparity.  Some indications of the water-to-land transition and other aspects of scorpion evolution are evident in fossils and the ontogeny of extant species.

Scorpions were present during Pangaea, apparently dispersed with the continents and are now widely distributed.  Extant species show conservative evolution except for differences in venom toxicity and maternal mechanisms and structures for embryo nourishment in utero.  These structures are mainly non-placental, without specialized vascularization, in contrast to viviparous fish (more than 40 families).  The complexities of the latter are well studied, and scorpion viviparity provides an invertebrate comparison with the evolution of viviparity in higher forms.

Some Representative Publications....

  • Farley, R. D. (2008) Development of respiratory structures in embryos and first and second instars of the bark scorpion, Centruroides gracilis (Scorpiones: Buthidae). J. Morphol. 269:1134-1156.
  • Farley, R. D. (2005) Developmental changes in the embryo, pronymph, and first molt of the scorpion Centruroides vittatus (Scorpiones: Buthidae). J. Morphol. 265:1-27.
  • Farley, R.  (2001)  Structure, reproduction and development.  In: P.  H.  Brownell and G.  A.  Polis (eds.): Scorpion Biology and Research. Oxford/New York: Oxford University Press.  pp. 3-78.
  • Farley, R.D. (2001) Development of segments and appendages in embryos of the desert scorpion Pauroroctunus mesaensis (Scorpionidae: Vaejovidae). J. Morphol. 250:70-88
  • Farley, R.D. (2001) Development of pectines in embryos of Pauroroctunus mesaensis Stahnke, 1957 (Scorpiones: Vaejovidae). In: V. Fet and P.A. Selden (eds.). Scorpions 2001: Memoriam Gary A. Polis. Burnham Beeches, Bucks, UK: British Arachnol. Soc. Pp. 369-381.
  • Farley, R. (2001) Abdominal plates, spiracles and sternites in the ventral mesosoma of embryos of the desert scorpion Paruroctonus mesaensis (Scorpiones: Vaejovidae). Invertebr. Reprod. Dev. 40:193-208.
  • Farley, R.  (1999)  Scorpiones.  In: F.  W.  Harrison and R.F. Foelix (eds.), Microscopic Anatomy of Invertebrates, Vol.  8A:  Chelicerate Arthropods.  New York: Wiley-Liss.  Pp. 117-222.

Recent Teaching....

  • Biology 171, Human Physiology
  • Biology 176L, Comparative Neurophysiology Laboratory