Mark E. Siddall
Curator of Annelida and Protozoa
American Museum of Natural History
siddall at

     The Leech Lab

  Annelida TOL
  Leech REVSYS
  Leech PEET


  Bloodlust IV - Rwanda
  Bloodlust II - Australia
  South Africa
  Bloodlust I
  French Guyana
  Bolivian Andes


  Ocean Life
  Undersea Oasis



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  Hennig Society
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Leech Blog

     Our research program is principally taxon based. It is broadly interested in taxonomy, systematics, phylogeny and evolution of certain largely neglected groups. Those groups are first and foremost Hirudinida (leeches), but also Annelida more broadly, Haplosporida and Proteobacteria as well in the context of symbiotic associations. Students and postdocs in the lab have variously studied tapeworms of elasmobranchs, Amphipoda, Alpheidae (eusocial snapping shrimp), malaria parasites and Foraminifera. Most of our work concerns the freshwater and terrestrial realms.

     We have had six years of funding from the National Science Foundation through a Partnerships for Enhancing Expertise in Taxonomy (PEET) grant. That research focus sought to accomplish, first and foremost, the training of graduate and undergraduate students in alpha taxonomy, systematics and phylogeny of leeches. Most of that work has concerned leeches, has had a global reach and has included major phylogenetic revisions of half of all of the families of leeches. The most significant contributions have been a determination of the relative familial relationships of leeches, discovery of the basal branches of all major leech, phylogenetic and biogeographic investigations of terrestrialism in several major radiations of IndoPacific tropical leeches, phylogenetic evaluation of evolutionary significant issues including parental care, habitat preference, host preference, feeding behaviour and reproductive behaviour. A newly awarded REVSYS grant from NSF will explore the diversity and evolutionary history of the notorious bloodfeeders in the Hirudinidae.

     International collaborations have culminated in a Tree of Life for the phylum Annelida based on multiple nuclear and mitochondrial loci. This work established the position of all major radiations of polychaetous annelids, the deep-sea hydrothermal vent worms - Pogonophora and Vestimentifera (Siboglinidae) - the origin of the aquatic Oligocaheta, as well as the relative placement of presumed non-annelids like Sipunculida and Echiura. Recent analyses involved evolutionary relationships of the reproductively diverse polychaete family Syllidae including more than 120 species.

Microbial Diversity
     Investigations of tight bacterial symbioses of microbes with leeches required expeditions to collect the Giant Amazonian leech and the notorious Hippo leech feeding exclusively from the rectal tissues of its host. The work established a new genus of alphaproteobacteria, and determined that there were three independent colonizations of bloodfeeding leeches by these symbiotic relationships: one from the nitrogen-fixing Rhizobeacea and two separately from the broadly endosymbiotic Enterobacteraciae A combination of genomic sequences, biochemical and antibiotic tests has demonstrated that the gut flora of the North American Medicinal leeches is dominated by Aeromonas jandaei as opposed to Aeromonas veronii of other medicinal leeches. Collaborative work continues intensively on the Haplosporida, parasites of which are responsible for the decimation of oyster stocks in the Chesapeake Bay. Recent work saw the publication of the definitive phylogeny of the phylum and its place in a whole Eukaryota Tree of Life with the Cercozoa.

Mark also serves as:

  • Curator of Annelida

  • (temporarily responsible for molluscs too)

  • Program Director for Research Experiences for Undergraduates in evolutionary biology and systematics at AMNH,

  • Treasurer of the Willi Hennig Society.

  • Councillor of the American Society of Parasitologists