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Leeches either have a pharynx that they can protrude, commonly called a proboscis, or a pharynx that they cannot protrude, which in some groups is armed with jaws. [38] In the proboscisless leeches, the jaws (if any) of Arhynchobdellids are at the front of the mouth, and have three blades set at an angle to each other.
These leeches have five pairs of eyes, with the last two separated by two eyeless segments. The family is monotypic, containing only the subfamily Haemadipsinae, though as the family can apparently be divided into two or three distinct lineages, at least one of the proposed splits, while not a distinct family, might be a valid subfamily. [1]
Leeches, order Hirudinida, [4] mostly have flattened bodies, usually tapered at both ends. They have a fixed number of segments, 33, but the segmentation is not visible externally because the cuticle is marked with annulations. Leeches do not bear chaetae. The front few segments or head have been modified into a sucker that usually surrounds ...
Some clitellates have sticky pads in the roofs of their mouths, and some of these can evert the pads to capture prey. Leeches often have an eversible proboscis, or a muscular pharynx with two or three teeth. [23]
The price of leeches varied between one penny and threepence halfpenny each. In 1832 leeches accounted for 4.4% of the total hospital expenditure. The hospital maintained an aquarium for leeches until the 1930s. [15] The use of leeches began to become less widespread towards the end of the 19th century. [5]
Haementeria ghilianii is a species of leech in the Glossiphoniidae family, comprising freshwater proboscis-bearing leeches. Colloquially, they are known as the Amazon giant leech . Following its initial description in 1849, additional details were provided based on specimens from French Guiana in 1899, after which the species was largely ...
Each segment of the leech's body (and all leeches have 32) has three or four annuli. [2] [3]: 236 They are large leeches; one species, Pontobdella novaezealandiae, can grow as long as 20 centimetres. [3]: 236 [4]
As in other species of leech, a cocoon is secreted by the clitellum, a thickened glandular section of the body wall behind the head, and this moves forwards over the head, receiving fertilised eggs from the gonopore on the way. [5] In some areas, Erpobdella obscura has a semelparous life history, i.e., the leech dies after reproduction.