I took this photo near the Sapanca lake in Kocaeli.Although the winter season and weather was 12 degrees,all the snake had come out.We saw 4 N. tessellata and 1 dead snake. Natrix tessellata (Laurenti, 1768) (Dice Snake) Recognition: A Colubroid “semi-venomous (rear-fanged)” snake up to 120 cm total length. It has a slender neck. Preoculare 2-4 (There’s 1 in N. natrix, a widespread Nartix species in Turkey), supralabialia 8, dorsalia 19 (commonly), ventralia 155-190. Dorsal scales are keeled. Colour and Pattern: Dorsal is olive-green or greyish-brown with black or white markings on it. Sometimes, whole black “melanistic” forms can be seen. There’s a marking on the neck with a “reverse V” shape. Ventral is pink or yellowish-white in the front, with black markings on it (You can see in the workshop). It (ventral) is black in posterior part of the body, with yellowish or pinkish-white markings. Biology-Ecology and Distribution: They live near the rivers or lakes or around. They hibernate together in large groups. They can move easily in the water. It spreads a bad-smelling secretion or gase from cloaca when it’s disturbed. Sometimes it doesn’t move and seems to be dead (like N. natrix). A phrase “playing posum” or a term “thanatosis” is used for this behaviour. They feed mainly on fish, also they feed on amphibians and other aquatic animals. During the mating season (March, April, May) they congregate in large groups. They lay egg in usually in July and one clutch consist of 2-25 egg. The young snakes hatch in early September. It distributes from West Europa (from France in the west) to western China, including Turkey, southern Russia, Afghanistan and Pakistan. Also its distribution includes the Middle East (from Syria to Yemen) and northeastern Egypt. It’s found in all regions in Turkey with a vertical distribution up to 2500 m. Venom: It’a “semi-venomous” or “rear-fanged” snake (opisthoglyphous). Because venom fangs are located on the back of the maxilla and their venom is not dangerous for human, it’s called like that (semi-venomous). There are 4 (5?) rear-fanged snake species in Turkey and they are not dangerous for human. But some rear-fanged species that are not distributed in Turkey are dangerous (even fatally) to man (such as Boiga spp., Dispholidus spp.). Colubrid venom is neurotoxic in general. The LD50 for the venom of N. tessellata is 25.0 (microg/g) in mice. Its venom shows arginine esterase, acid phosphatase, alkaline phosphatase, protease and phosphodiesterase actvity. Nasit IGCI Systematics is at the end of the note. ----------------------------------------------------- Natrix tessellata (Laurenti, 1768) (Su Y?lan?) Tan?m?: Toplam uzunlugu 120 cm kadar olabilen, ince boyunlu ve “yar? zehirli” bir y?land?r (Colubroid). Gozun onunde 2-4 preocular plak bulunur (Turkiye’de yayg?n olarak bulunan N. natrix turunde bu say? 1’dir). S?rt pullar? bariz karinal?d?r. Supralabialia 8, s?rt pullar? 19, ventralia 155-190’d?r. Renk ve Desen Ozellikleri: Dorsali zeytuni, zeytuni yesil ya da gri-kahverengidir ve uzerinde siyah veya beyaz lekeler vard?r. Bazen tamamen siyah olan formlar? da olabilir. Ense k?sm?nda cogunlukla “ters V harfi” seklinde bir leke bulunur. Ventrali, on tarafta pembemsi veya sar?ms? beyaz olup, uzeri siyah lekelidir (WS’de gorebilirsiniz). Arka tarafta ise zemin rengi siyaht?r ve bu zemin uzerinde sar?ms? yahut pembemsi beyaz dag?n?k lekeler bulunur. Biyolojik-Ekolojik Ozellikleri ve Yay?l?s?: Dere ve gol kenarlar?nda veya buralara yak?n yerlerde yasarlar ve toplu halde k?s uykusuna yatarlar. Suyun icinde de rahatl?kla hareket edebilirler. Rahats?z edildiklerinde kloak bezlerinden pis kokulu gaz veya s?v? c?kar?rlar. Bazen hareketsiz kalarak veya ters donerek olu taklidi yapar (N. natrix gibi). Daha cok bal?kla beslenirler, kurbaga ve diger su hayvanlar?yla da beslenebilirler. Ciftlesme mevsimlerinde (Mart, Nisan, May?s) buyuk gruplar halinde toplan?rlar. Yumurtlama genellikle Temmuz ay?nda olur ve bir seferde 5-25 kadar yumurta b?rak?rlar. Yavrular Eylul ay?n?n baslar?nda yumurtadan c?karlar. Bat? Avrupa’dan (bat?da Fransa’dan), Turkiye Rusya’n?n guneyi, Afganistan ve Pakistan’? da kapsayacak sekilde, Cin’in bat?s?na kadar ve yay?l?s? vard?r. Orta Dogu’da ise Suriye’den Yemen’e kadar yay?lm?st?r, ayr?ca M?s?r’?n kuzeydogusunda da bulunmaktad?r. Turkiye’nin her yerinde bulunur. Deniz seviyesinden 2500 m’ye kadar c?kabilirler. Zehri: Bu tur, “yar? zehirli” olarak isimlendirilen y?lanlardand?r (opisthoglyphous). Zehir disleri maksil kemiginin arka taraf?nda bulundugundan ve zehirleri genellikle insan icin tehlikeli olmad?g?ndan bu isim verilmistir. Turkiye’de 4 (5?) “yar? zehirli” y?lan turu vard?r ve insan icin tehlikeli degillerdir, ancak Turkiye’de yay?l?s? olmayan baz? yar? zehirli y?lan turleri insan icin tehlike arz edebilir ve hatta oldurucu olabilir (or: Boiga spp., Dispholidus spp.). Colubridlerin zehri genellikle sinir sistemi uzerinde etkilidir (norotoksi

(August 14, 1883 – October 27, 1941) was a pioneering African American biologist, academic and science writer. Just's primary legacy is his recognition of the fundamental role of the cell surface in the development of organisms. In his work within marine biology, cytology and parthenogenesis, he advocated the study of whole cells under normal conditions, rather than simply breaking them apart in a laboratory setting. When he graduated from Dartmouth, Just faced the same problems as all black college graduates of his time: no matter how brilliant they were or how high were their grades, it was almost impossible for blacks to become faculty members of white colleges or universities. Just then took what seemed to be the best choices available to him and was appointed to a teaching position at historically-black Howard University in Washington, D.C.. In 1910, he was put in charge of the newly-formed biology department by Wilbur P. Thirkield. In 1912, he became head of the Department of Zoology, a position he held until his death in 1941. Just was soon introduced to Dr. Frank R. Lillie, head of the biology department at the University of Chicago. Lillie, who was also chief of the Marine Biological Laboratory (MBL) at Woods Hole, Massachusetts, invited Just to spend the summer of 1909 as his research assistant at the MBL. For the next 20 years, Just spent every summer but one at MBL. On June 12, 1912 Ernest married Ethel Highwarden, who taught German at Howard University. They had three children: Margaret, Highwarden, and Maribel. In 1915, Just took a leave of absence from Howard to enroll in an advanced academic program at the University of Chicago. That same year, Just, who was gaining a national reputation as an outstanding young scientist, was the first recipient of the NAACP's Spingarn Medal on February 12, 1915. In June 1916, Just received his Ph.D. in experimental embryology, with a thesis on the mechanics of fertilization, from the University of Chicago, becoming one of the handful of blacks who had gained this degree from a major university. Just, however, became frustrated because he could not attain an appointment to a major American university. He wanted a position that would provide a steady income and allow him to spend more time with his research. The same year, he conducted experiments at the zoological station in Naples, Italy. Then, in 1930, he became the first American to be invited to the Kaiser Wilhelm Institute in Berlin, Germany, where several Nobel Prize winners conducted research. Beginning in 1933, Just ceased his work in Germany when the Nazis began to take the control of the country. He relocated his European-based studies to Paris. Just authored two books, Basic Methods for Experiments on Eggs of Marine Mammals (1922) and The Biology of the Cell Surface (1939), and he also published several scientific papers relating to cell cytoplasm. At the outbreak of World War II, Just was working at the "Station Biologique" in Roscoff, France, researching the paper that would become Unsolved Problems of General Biology. Although the French government requested foreigners to evacuate the country, Just remained to complete his work. In 1940, Germany invaded France and Just was briefly imprisoned in a prisoner-of-war camp. He was rescued by the U.S. State Department and returned to his home country in September 1940. However, Just had been very ill for months prior to his arrest and his condition deteriorated in prison and on the journey back to the U.S. In the fall of 1941, he was diagnosed with pancreatic cancer, and died shortly thereafter. Just was the subject of the 1983 biography Black Apollo of Science: The Life of Ernest Everett Just by Kenneth R. Manning. The book received the 1983 Pfizer Award and was a finalist for the 1984 Pulitzer Prize for Biography or Autobiography. In 1996, the U.S. Postal Service issued a commemorative stamp honoring Just. Beginning in 2000, the Medical University of South Carolina has hosted the annual Ernest E. Just Symposium to encourage non-white students to pursue careers in biomedical sciences and health professions. In 2002, scholar Molefi Kete Asante included Just on his list of the 100 Greatest African Americans. Wikipedia