Glossiphoniidae

Taxobox
name = Glossiphoniidae
regnum = Animalia
subregnum = Eumetazoa
phylum = Annelida
classis = Clitellata
subclassis = Hirudinea
infraclassis = Euhirudinea
ordo = Rhynchobdellida
familia = Glossiphoniidae
familia_authority =
subdivision_ranks = Subfamilies
subdivision =
Glossiphoniinae

Haementeriinae
Theromyzinae and see text

Glossiphoniidae are the family called freshwater jawless leeches or glossiphoniids. They are one of the main groups of Rhynchobdellida, true leeches with a proboscis. These leeches are generally flattened, and have a poorly defined anterior sucker. Most suck the blood of freshwater vertebrates like amphibians and [8aquatic] turtles, but some feed on the hemolymph of invertebrates like oligochaetes and water snails instead.

Freshwater jawless leeches are remarkable for their parental care, the most highly developed one among the known annelids. They produce a membranaceous bag to hold the eggs, which is carried on the underside. The young attach to the parent's belly after hatching and are thus ferried to their first meal.

There is considerable interest in the symbiontic bacteria that at least some glossiphoniids carry in specialized compartments of the esophagus to aid in digesting their meals. "Haementeria" as well as "Placobdelloides" have Enterobacteriaceae symbionts, while "Placobdella" harbours peculiar and independently derived Alpha Proteobacteria.

ystematics and taxonomy

The Theromyzinae are a rather enigmatic subfamily and their relationship to other glossiphoniids has as of yet resisted elucidation. Also, there are several genera of more basal or uncertain position:
* "Batracobdella"
* "Boreobdella"
* "Marsupiobdella"
* "Placobdella" Blanchard, 1893 - includes "Desserobdella" Barta & Sawyer, 1990 and "Oligobdella" Moore, 1918, formerly in Glossiphoniinae
* "Placobdelloides" Sawyer, 1986 - possibly paraphyletic

Medical importance

While glossiphoniids are not among the medical leeches due to them not feeding on humans, they are nonetheless of high medical interest. Their saliva, like that of all blood- or haemolymph-feeding leeches, contains anticoagulant compounds which, being useful in therapy of some cardiovascular diseases, are of potentially high commercial value. Antistasin and related inhibitors of thrombokinase a like ghilanten, lefaxin and therostatin have been derived from "Haementeria" species and "Theromyzon tessulatum". These substances also seem to prevent certain tumors from metastasizing. Also from "Haementeria" are the fibrin stabilizing factor a inhibitor tridegin, a platelet adhesion inhibitor (LAPP), and the fibrinogen-dissolving enzymes hementin and hementerin. "T. tessulatum" also yields therin, theromin and tessulin, which inhibit protease activity. Ornatins, which are antiplatelet glycoprotein IIb-IIIa antagonists, were discovered in "Placobdella ornata", and several species have yielded hyaluronidases.