Glossiphoniidae

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Glossiphoniidae
Scientific classification
Kingdom: Animalia Subkingdom: Eumetazoa Phylum: Annelida Class: Clitellata Subclass: Hirudinea Infraclass: Euhirudinea Order: Rhynchobdellida Family: Glossiphoniidae
Subfamilies
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.

Tehre 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.

[edit] Systematics 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

[edit] 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.