West African crocodile

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West African crocodile
West African crocodile in Copenhagen Zoo.

West African crocodile in Copenhagen Zoo .

Systematics
without rank: Sauropsida
without rank: Archosauria
Order : Crocodiles (crocodylia)
Family : Real crocodiles (Crocodylidae)
Genre : Crocodylus
Type : West African crocodile
Scientific name
Crocodylus suchus
E. Geoffroy Saint-Hilaire , 1807

The West African crocodile ( Crocodylus suchus ) is a type of crocodile (Crocodylia) from the family of real crocodiles (Crocodylidae). The species was described as early as 1807 by the French zoologist Étienne Geoffroy Saint-Hilaire , but later synonymous with the Nile crocodile ( Crocodylus niloticus ) . Only DNA comparisons of populations of small crocodiles from Mauritania and Chad and of several 2000 year old Egyptian crocodile mummies with Nile crocodile populations from East Africa and Madagascar provided evidence of the independence of the West African crocodile. The Nile crocodile is therefore more closely related to the four Central and South American crocodylus species ( bumpy crocodile , Cuban crocodile , Orinoco crocodile and pointed crocodile ) than to the West African crocodile.

The West African crocodile is found in western Africa from Mauritania and Senegal to Chad, the Central African Republic and Equatorial Guinea . In contrast to the Nile crocodile, which lives in a more humid climate closer to the coast, it is more common in waters in the dry interior of the country and is also native to various Sahara oases with open waters. In the past it also lived in the Nile. All the crocodile mummies examined come from the West African crocodile, so that it can be assumed that - as Herodotus already established - the ancient Egyptians knew the difference between the two crocodile species living on the Nile and they were the smaller and less dangerous species for religious ceremonies with the sacred animals used (see Sobek ).

Outwardly, the West African crocodile can hardly be distinguished from the Nile crocodile, but the two species have a different skull morphology and a different arrangement of the scales underlaid by bone plates. A formal re-description of the species is still pending.

Status of the Northern Populations

The species was distributed in and on the edge of numerous mountain ranges in the Sahara until the 20th century. Habitats were deep, ravine-like cuts in the mountains as well as lagoons and shallow water lakes at the confluence of valleys in the plain. The completely isolated relic occurrences, surrounded by desert, are considered to be the last remnants of a formerly closed distribution of a more humid period in the Middle Holocene around 7000 years ago, which finally ended around 3000 years ago when the monsoon influence became less and less noticeable further north. Many of these populations did not become extinct until the beginning of the 20th century. The former distribution almost reached the Mediterranean coast at Chott el Djerid in northern Tunisia and almost the Atlantic in Wadi Draa in Morocco. Other extinct populations existed e.g. B. in the Hoggar Plateau and Tassili in Algeria.

After the "Sahara crocodile" was thought to be extinct at times, a few populations in the south of the Sahara have been rediscovered or confirmed in recent years. According to this, there are still populations in the Ennedi massif in Chad and in some of the Tagant mountains in Mauritania. The population is fragmented into a multitude of tiny individual occurrences, none of which presumably exceed 40 animals.

Way of life

The crocodiles live in oases with standing water, called tamourts there, and in underground spring water reservoirs , so-called Gueltas . Their main diet is made up of fish and frogs, occasionally birds and small animals and only rarely goats or sheep that are brought to water.

literature

  • A. Schmitz, P. Mausfeld, E. Hekkala, T. Shine, H. Nickel, G. Amato, W. Böhme: Molecular evidence for species level divergence in African Nile crocodiles Crocodylus niloticus (Laurenti, 1786). Comptes Rendus Palevol. Vol. 2, 2003, pp. 703-712, doi: 10.1016 / j.crpv.2003.07.002 .
  • E. Hekkala, MH Shirley, G. Amato, JD Austin, S. Charter, J. Thorbjarnarson, KA Vliet, ML Houck, R. Desalle, MJ Blum: An ancient icon reveals new mysteries: Mummy DNA resurrects a cryptic species within the Nile crocodile. Molecular Ecology. Vol. 20, 2011, pp. 4199-4215, doi: 10.1111 / j.1365-294X.2011.05245.x

Individual evidence

  1. ↑ SH Geoffroy: Description de deux crocodiles qui existent dans le Nil, comparés au crocodile de Saint-Domingue. Annales du Muséum d'histoire naturelle, Paris. Vol. 10, 1807, pp. 67–86 (full text on BHL )
  2. ↑ Hekkala, E., Shirley, MH, Amato, G., Austin, JD, Charter, S., Thorbjarnarson, J. , Vliet, KA, Houck, ML, Desalle, R., and Blum, MJ: An ancient icon reveals new mysteries: Mummy DNA resurrects a cryptic species within the Nile crocodile . In: Molecular Ecology . 2011. doi : 10.1111 / j.1365-294X.2011.05245.x .
  3. ↑ Klaas de Smet: Status of the Nile crocodile in the Sahara desert. Hydrobiologia. Vol. 391, No. 1-3, 1998, pp. 81-86, doi: 10.1023 / A: 1003592123079 .
  4. ↑ José Luis Tellería, Hamoud El Mamy Ghaillani, José María Fernández-Palacios, Juan Bartolomé, Emilio Montiano: Crocodiles Crocodylus niloticus as a focal species for conserving water resources in Mauritanian Sahara. Oryx. Vol. 42, No. 2, 2008, pp. 292-295, doi: 10.1017 / S0030605308007850 (alternative full text access : UCM ).
  5. ↑ José C. Brito, Fernando Martínez-Freiría, Pablo Sierra, Neftalí Sillero, Pedro Tarroso: Crocodiles in the Sahara Desert: An Update of Distribution, Habitats and Population Status for Conservation Planning in Mauritania. PLoS ONE. Vol. 6, No. 2, 2011, e14734, doi : 10.1371 / journal.pone.0014734

Web links

Commons : West African Crocodile  - Collection of images, videos and audio files