Determinants and consequences of interspecific body size variation in tetraphyllidean tapeworms

Haseeb Sajjad Randhawa, Robert Poulin

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


Tetraphyllidean cestodes are cosmopolitan, remarkably host specific, and form the most speciose and diverse group of helminths infecting elasmobranchs (sharks, skates and rays). They show substantial interspecific variation in a variety of morphological traits, including body size. Tetraphyllideans represent therefore, an ideal group in which to examine the relationship between parasite body size and abundance. The individual and combined effects of host size, environmental temperature, host habitat, host environment, host physiology, and host type (all likely correlates of parasite body size) on parasite length were assessed using general linear model analyses using data from 515 tetraphyllidean cestode species (182 species were included in analyses). The relationships between tetraphyllidean cestode length and intensity and abundance of infection were assessed using simple linear regression analyses. Due to the contrasting morphologies between shark and batoid hosts, and contrasting physiologies between sharks of the Lamnidae family and other sharks, analyses were repeated in different subsets based on host morphology and physiologies ("sharks" vs. batoids) to determine the influence of these variables on adult tetraphyllidean tapeworm body size. Results presented herein indicate that host body size, environmental temperature and host habitat are relatively important variables in models explaining interspecific variations in tetraphyllidean tapeworm length. In addition, a negative relationship between tetraphyllidean body size and intensity of infection was apparent. These results suggest that space constraints and ambient temperature, via their effects on metabolism and growth, determine adult tetraphyllidean cestode size. Consequently, a trade-off between size and numbers is possibly imposed by external forces influencing host size, hence limiting physical space or other resources available to the parasites.

Original languageEnglish
Pages (from-to)759-769
Number of pages11
Issue number4
Publication statusPublished - Sept 2009

Bibliographical note

Funding Information:
Acknowledgments The diligence of two anonymous reviewers is gratefully acknowledged and contributed to improving this manuscript. We thank David R. Anderson for advice regarding our analyses, Tommy Leung for translation of papers from Chinese to English and members of the Evolutionary and Ecological Parasitology Research Group at the University of Otago for useful comments on a previous version of this manuscript. Financial support from the New Brunswick Museum, through the Florence M. Christie Research Fellowship in Zoology to H. S. R., is gratefully acknowledged.

Other keywords

  • Abundance
  • Body size
  • Depth
  • Latitude
  • Tetraphyllidea


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