Introduction
Kingdom: Animalia
Phylum: Annelida Class: Clitellata Order: Hirudinida Suborder: Arhynchobdellida Family: Hirudinidae Genus: Hirudo Species: H. nipponia |
Hirudo nipponia is a species of east Asian leech. Their hosts include many amphibians, reptiles, and mammals, including humans[3]. Typically they're found in rice paddies, irrigation and drainage ditches, open sewers, and ponds[3]. Until recently they were endemic to Japan, Korea, China, Taiwan, the Ryukyu Islands, and eastern Russian. However H. nipponia has disappeared from the rice paddies and drainage ditches in Taiwan, and hardly been found in the other habitats, possibly due to the use of pesticides and fertilizers[3]. H. nipponia is the sister species of the more well-known H. medicinalis.
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Description
They measure 30-60mm, are green to olive colored with five yellow stripes outlined in black, and also have five pairs of eyes spread out longitudinally near the front of the body[3].
As annelids, Hirudo are coelomates[1], and rather than a vesseled circulatory system, hemolymph flows freely through the coelom to bathe the internal organs (arynchobdellida)[2]. They have suckers at both ends (euhirudinea)[2], which contain three large crescent-shaped jaws with 55-70 teeth[3], that cut an opening into the host[1]. Surrounding the jaws are numerous salivary glands[3]. H. nipponia lack chaetae (bristles like the ones on earthworms)[2]. One last thing worth noting is the head end of Hirudo is wide and round, necessary to distinguish it from Whitmania leeches, which are almost identical but have thinner, tapering heads[3]. |
Feeding
Unlike some leeches, H. nipponia can swim, and will target potential aquatic hosts by their vibrations[3]. The leech secretes an anesthetic onto the host, which often precludes detection of the leech. Following the incision, hirudin is secreted to prevent coaulation and keep the blood flowing freely[1].
In addition to amphibians, reptiles, and mammals, they may also attack some fishes. H. nipponia have also been reported attacking other leeches (even ones larger than they are) and feeding on the host leech's hemolymph or directly on the blood in the digestive tract taken earlier from the host leech's previous host. Leech hosts don't typically survive the H. nipponia attack[3].
In addition to amphibians, reptiles, and mammals, they may also attack some fishes. H. nipponia have also been reported attacking other leeches (even ones larger than they are) and feeding on the host leech's hemolymph or directly on the blood in the digestive tract taken earlier from the host leech's previous host. Leech hosts don't typically survive the H. nipponia attack[3].
References
[1]Campbell & Reece, Biology 8th Edition
[2]http://australianmuseum.net.au/Leeches
[3]http://clitellates.biota.biodiv.tw/pages/1131
[2]http://australianmuseum.net.au/Leeches
[3]http://clitellates.biota.biodiv.tw/pages/1131