The freshwater crocodile ( Crocodylus johnstoni or Crocodylus johnsoni ; see below ), besides known as the Australian freshwater crocodile, Johnstone’s crocodile or besides known as freshie, is a species of crocodile endemic to the northern regions of Australia. Unlike their a lot larger australian relative, the seawater crocodile, fresh water crocodiles are not known as man-eaters, although they bite in self defense mechanism, and brief, nonfatal attacks have occurred, apparently the result of misguided identity .
Taxonomy and etymology [edit ]
When Gerard Krefft named the species in 1873, [ 7 ] he intended to commemorate the serviceman who first reported it to him, australian native police policeman and amateur naturalist Robert Arthur Johnstone ( 1843–1905 ). [ 6 ] [ 8 ] however, Krefft made an error in writing the name, and for many years, the species has been known as C. johnsoni. late studies of Krefft ‘s papers have determined the correct spell of the name, and much of the literature has been updated to the correct custom, but both versions still exist. According to the rules of the International Code of Zoological Nomenclature, the epithet johnstoni ( preferably than the original johnsoni ) is chastise. [ 9 ] [ 10 ] [ 11 ]
Reading: Freshwater crocodile – Wikipedia
development [edit ]
The genus Crocodylus probable originated in Africa and radiated outwards towards Southeast Asia and the Americas, [ 12 ] although an Australia/Asia origin has besides been considered. [ 13 ] Phylogenetic tell supports Crocodylus diverging from its closest late relative, the extinct Voay of Madagascar, around 25 million years ago, near the Oligocene / Miocene limit. [ 12 ]
evolution [edit ]
Below is a cladogram based on a 2018 tip dating analyze by Lee & Yates simultaneously using morphologic, molecular ( DNA sequencing ), and stratigraphic ( dodo age ) datum, [ 14 ] as revised by the 2021 Hekkala et al. paleogenomics study using DNA extracted from the extinct Voay. [ 12 ]
description [edit ]
The fresh water crocodile is a relatively small crocodilian reptile. Males can grow to 2.3–3.0 thousand ( 7.5–9.8 foot ) long, while females reach a maximum size of 2.1 thousand ( 6.9 foot ). [ 9 ] Males normally weigh around 70 kilogram ( 150 pound ), with large specimens up to 100 kg ( 220 pound ) or more, against the female weight of 40 kg ( 88 pound ). [ 15 ] In areas such as Lake Argyle and Katherine Gorge, a handful of confirmed 4 metres ( 13 foot ) individuals exist. This species is shy and has a slender snout and slenderly smaller tooth than the dangerous seawater crocodile. The body color is clean brown with dark bands on the body and tail—these tend to be broken up near the neck. Some individuals possess distinct bands or speckling on the snout. consistency scales are relatively boastfully, with wide-eyed, close-knit, armored plates on the rear. Rounded, gravelly scales cover the flanks and outsides of the peg. [ 9 ]
distribution and habitat [edit ]
fresh water crocodiles are found in western Australia, Queensland, and the Northern Territory. Main habitats include fresh water wetlands, billabongs, rivers, and creek. This species can live in areas where seawater crocodiles can not, and are known to inhabit areas above the escarpment in Kakadu National Park and in identical arid and rocky conditions ( such as Katherine Gorge, where they are common and are relatively safe from seawater crocodiles during the dry season ). however, they are however systematically found in subordinate billabongs, living alongside the seawater crocodiles near the tidal reaches of rivers. In May 2013, a fresh water crocodile was seen in a river near the defect town of Birdsville, hundreds of kilometres south of their normal range. A local commando suggested that years of deluge may have washed the animal south, or it may have been dumped as a juvenile. [ 16 ]
Biology and behavior [edit ]
They compete ailing with seawater crocodiles, but are seawater tolerant. Adult crocodiles eat fish, birds, bats, reptiles, and amphibians, although larger individuals may take prey arsenic bombastic as a wallaby. An individual being eaten by an olive python Liasis olivaceus has been filmed ; it was reported to have succumbed after a conflict of around five hours. [ 17 ]
reproduction [edit ]
Eggs are laid in holes during the australian dry season ( normally in August ) and hatch at the beginning of the wet temper ( November/December ). The crocodiles do not defend their nests during incubation. From one to five days anterior to hatching, the youthful begin to call from within the eggs. This induces and synchronizes hatching in siblings and stimulates adults to open the nest. If the pornographic that opens a given nest is the female which laid the eggs is unknown. As young issue from the nest, the adult picks them up one by one in the gratuity of its sass and transports them to the urine. Adults may besides assist young in breaking through the egg shell by chewing or manipulating the eggs in its mouth. [ 18 ]
diet [edit ]
Feeding in the wild, fresh water crocodiles eat a variety of invertebrate and vertebrate prey. These prey may include crustaceans, insects, spiders, fishes, frogs, turtles, snakes, birds, and versatile mammals. Insects appear to be the most common food, followed by fish. Small raven is normally obtained by a ‘sit-and-wait ‘ method acting, whereby the crocodile lies inactive in shallow water and waits for fish and insects to come within close rate, before they are snapped up in a sideways action. however, larger prey such as wallabies and water birds may be stalked and ambushed in a manner similar to that of the seawater crocodile .
digestive organization [edit ]
The crocodiles have teeth that have adapted for capturing and holding prey, and food is swallowed without chewing. The digestive tract is short, as their food is relatively simple to swallow and digest. The stomach has two compartments – a brawny gizzard that grinds food, and a digestive chamber where enzymes act on the food. The crocodile ‘s stomach is relatively more acidic than that of any other vertebrate and contains ridges that lead to the mechanical breakdown of food. Digestion takes identify at a fast tempo at high temperatures.
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circulation system [edit ]
The hearts of early reptiles are designed to contain three sections, including two atria and one ventricle. The correctly atrium, which collects the returned deoxygenated lineage and the leave atrium, which collects the oxygenate blood collected from pneumonic arteries of the lung, takes the blood to a common ventricle. When just one ventricle is available to receive and mix oxygenated and deoxygenated lineage and pump it to the torso, the assortment of blood the body receives has relatively less oxygen. Crocodiles have a more building complex vertebrate circulatory system, with a four-chambered heart, including two ventricles. Like birds and mammals, crocodiles have heart valves that direct blood flows in a individual direction through the heart chambers. When under body of water, the crocodile ‘s heart rate slows down to one to two beats a minute, and muscles receive less lineage hang. When it comes out of the urine and takes a breath, its kernel rate speeds up in seconds, and the muscles receive oxygen-rich blood. Unlike many marine mammals, crocodiles have merely a small sum of myoglobin to store oxygen in their muscles .
conservation status [edit ]
Until recently, the fresh water crocodile was park in northern Australia, particularly where seawater crocodiles are absent ( such as more arid inland areas and higher elevations ). In holocene years, the population has dropped dramatically due to the consumption of the invasive cane frog. The frog is poisonous to freshwater crocodiles, although not to saltwater crocodiles, and the frog is rampant throughout the australian wilderness. [ 19 ] The crocodiles are besides infected by Griphobilharzia amoena, a epenthetic fluke, in regions such as Darwin. [ 20 ]
kinship with humans [edit ]
Although the fresh water crocodile does not attack humans as electric potential prey, it can deliver a nasty sting. Brief and quickly abandoned attacks have occurred, and were likely the result of misguided identity ( mistaking a separate of the human as a typical prey item ). [ 21 ] [ 22 ] other attacks have occurred in self refutation when the crocodile was touched or approached besides closely. [ 23 ] No human fatalities are known to have been caused by this species. [ 23 ] A few incidents have been reported where people have been bitten whilst swimming with fresh water crocodiles, and others incurred during scientific study. An attack by a fresh water crocodile on a human was recorded at Barramundi Gorge ( besides known as Maguk ) in Kakadu National Park and resulted in minor injuries ; the victim managed to swim and walk away from the attack. He had apparently passed directly over the crocodile in the water. In general, though, swimming with this species is still considered safe, so long as they are not aggravated. [ 24 ] There has, however, been a fresh water crocodile attack at Lake Argyle. [ 25 ]
gallery [edit ]
- head of a fresh water crocodile
- Freshwater crocodile basking on a log
- diverse skull views of an “ Australia crocodile ” ( Crocodylus johnsoni )
References [edit ]
far take [edit ]
- Boulenger GA (1889). Catalogue of the Chelonians, Rhynchocephalians, and Crocodiles in the British Museum (Natural History). New Edition. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). x + 311 pp. + Plates I–III. (Crocodilus johnstonii, pp. 279–280).
- Cogger H (2014). Reptiles and Amphibians of Australia, Seventh Edition. Clayton, Victoria, Australia: CSIRO Publishing. xxx + 1,033 pp. ISBN 978-0643100350.
- Gray JE (1874). “On Crocodilus johnstoni, Krefft”. Proc. Zool. Soc. London 1874: 177–178 + Plate XXVII.
- Krefft G (1873). “Remarks on Australian Crocodiles, and Description of a New Species”. Proc. Zool. Soc. London. 1873: 334–335. (Crocodilus johnsoni, new species, p. 335).