| Haementeria ghilianii | |
|---|---|
 | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Annelida |
| Clade: | Pleistoannelida |
| Clade: | Sedentaria |
| Class: | Clitellata |
| Subclass: | Hirudinea |
| Order: | Rhynchobdellida |
| Family: | Glossiphoniidae |
| Genus: | Haementeria |
| Species: | H. ghilianii |
| Binomial name | |
| Haementeria ghilianii de Filippi, 1849 | |
Haementeria ghilianii, commonly known as the Amazon giant leech, is one of the world's largest species of leeches.
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. The species was declared extinct in 1893 after no wild specimen could be found. [1]
In the 1970s, Dr. Roy Sawyer discovered two adult specimens in a pond located in French Guiana. One of these leeches, dubbed Grandma Moses, founded a successful breeding colony at UC Berkeley. This specimen produced 750 offspring. [1] Following Grandma Moses' death, the specimen was placed in the Smithsonian's National Invertebrate Collection. [2]
Haementeria ghilianii is a jawless, blood sucking leech. It can grow to 450 mm (17.7 in) in length and 100 mm (3.9 in) in width. [1] This makes it the largest freshwater leech known. [2] As adults, these leeches are a uniform greyish-brown color. Juveniles do not have a uniform color, but rather, a noncontinuous greyish-brown stripe and patches of color. The leeches form a "cobra hood" like shape that is widest in the center but tapers off on both ends. [1] [2] The wider end is where the proboscis is located, while the head is at the narrow end; H. ghilianii is made up 34 segments, each with its own ganglia. [3]
This species is hermaphroditic; the male reproductive system is 3 g (0.0066 lb) to 5 g (0.011 lb) while the female reproductive system is 10 g (0.022 lb). [2] [1] Growth is irregular, as the leech's body weight increases by 3 to 6 fold times per feeding. Fecundity is based upon the weight of the leech during oviposition; egg clutches range from 60 to 500 eggs. [4]
When stressed, leeches will produce mucus to evade predators. [3]
Unlike jawed leeches who use rows of teeth to puncture skin, Haementeria ghilianii uses a 10 centimetres (3.9 in) hypodermic needle style proboscis to feed. Bites are kept open by the fibrinogenolytic (breaks up fibrinogen) enzyme hementin, which is secreted from the proboscis' lumen; secretion is neurologically controlled. Hementin dissolves clots within the proboscis by breaking up the fibrinogen links between individual platelets. Once attached to a host, they release anticoagulants to prevent clotting, consuming blood at a rate of 0.14 ml to 15 ml per minute. [1] [5] Blood is moved into the digestive system through a series of undulation movements, and leeches can go months without feeding. [3] [5] Observed host species include humans, rabbits, and cows. [1] [5] Claims from 1899 state that leeches could aggregate to the point of killing birds and cattle. [3]
Haementeria ghilianii is endemic to the northern portions of the Amazon river, ranging from Venezuela and the Guianas. [1]
A thrombus, colloquially called a blood clot, is the final product of the blood coagulation step in hemostasis. There are two components to a thrombus: aggregated platelets and red blood cells that form a plug, and a mesh of cross-linked fibrin protein. The substance making up a thrombus is sometimes called cruor. A thrombus is a healthy response to injury intended to stop and prevent further bleeding, but can be harmful in thrombosis, when a clot obstructs blood flow through healthy blood vessels in the circulatory system.
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The arapaima, pirarucu, or paiche is any large species of bonytongue in the genus Arapaima native to the Amazon and Essequibo basins of South America. Arapaima is the type genus of the subfamily Arapaiminae within the family Osteoglossidae. They are among the world's largest freshwater fish, reaching as much as 3 m (9.8 ft) in length. They are an important food fish. They have declined in the native range due to overfishing and habitat loss. In contrast, arapaima have been introduced to several tropical regions outside the native range, where they are sometimes considered invasive species. In Kerala, India, arapaima escaped from aquaculture ponds after floods in 2018. Its Portuguese name, pirarucu, derives from the Tupi language words pira and urucum, meaning "red fish".
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Hementin is an anticoagulant protease from the salivary glands of the giant Amazon leech. Hementin is a calcium-dependent protease with a molecular weight of 80–120 kDa, and it contains 39 amino acid sequences. Hementin is present in both the anterior and posterior salivary glands, however it is mostly produced from certain cells in the anterior glands. The secretion of hementin is limited to the lumen of the proboscis, which the Amazon leech inserts into the host to suck blood. Hementin dissolves platelet-rich blood clots and lets the blood flow through the proboscis. Hementin is able to dissolve a type of blood clots that cannot be dissolved by other compounds, such as streptokinase and urokinase.
The Mekong giant catfish, is a large, threatened species of catfish in the shark catfish family (Pangasiidae), native to the Mekong basin in Southeast Asia and adjacent China. It is considered critically endangered due to overfishing and habitat loss.
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