Annelids are segmented worms that are found worldwide in most habitats, except the aerial and the most arid ones. Earthworms and leeches are the most familiar members of this group; however, most annelid diversity lies within the largely marine polychaetes. Until recently, Annelida was split into three major groups, each given class rank: Polychaeta (bristleworms), Oligochaeta (earthworms, etc.) and Hirudinea (leeches). The polychaetous annelids are not monophyletic insofar as "Polychaeta" would include Clitellata, Pogonophora, Vestimentifera and Echiura. It is also well recognized that leeches are nested within what was Oligochaeta. Comprehensive phylogenetic studies using molecular sequence data and morphology provide strong support that the "oligochaete" group Lumbriculida is the sister group to the ectoparasitic clade comprised of Hirudinida, Acanthobdellida and the crayfish-ectosymbiotic Branchiobdellida. The whole group, including both the traditional oligochaetes and the leeches are now simpy referred to as Clitellata. The museum has over 30,000 Annelids specimens in about 5,500 lots variously preserved in ethanol or on slide mounts.
Work on these collections has led to a large-scale tree of life for the phylum. Considerable attention has been focused on the leeches since 1999 by Curator Siddall. Notwithstanding the dubious utility of leeches for the treatment of obesity, hysteria and other ailments in the 19th century, the European medicinal leech, Hirudo medicinalis, since then has had a more legitimate role to play. The postoperative use of leeches for treatment of venous congestion following flap and replantation surgery was only recently approved by the USFDA. However, the anti-thrombin activity of its salivary peptide, hirudin, has a longer medical history including being central to the first human dialysis treatment and USFDA approval in 1998 for heparin-induced thrombocytopenia (HIT). Moreover, it is now well-understood that leeches produce a pharmacological cocktail of protease inhibitors that assist the leech both in terms of successful feeding and in preventing the bloodmeal from coagulating during the extended periods in which it must reside in the crop.
Curator-in-Charge: Dr. Mark Siddall
Collections Assistant: Sarfraz Lodhi