Crocodiles or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant members of the order Crocodilia, which includes the alligators and caimans, the gharial and false gharial among other extinct taxa.
Crocodilia is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period and are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria. Members of the order's total group, the clade Pseudosuchia, appeared about 250 million years ago in the Early Triassic period, and diversified during the Mesozoic era. The order Crocodilia includes the true crocodiles, the alligators and caimans, and the gharial and false gharial. Although the term 'crocodiles' is sometimes used to refer to all of these, crocodilians is a less ambiguous vernacular term for members of this group.
Gnathostomata are the jawed vertebrates. Gnathostome diversity comprises roughly 60,000 species, which accounts for 99% of all living vertebrates, including humans. In addition to opposing jaws, living gnathostomes have true teeth, paired appendages, the elastomeric protein of elastin, and a horizontal semicircular canal of the inner ear, along with physiological and cellular anatomical characters such as the myelin sheaths of neurons, and an adaptive immune system that has the discrete lymphoid organs of spleen and thymus, and uses V(D)J recombination to create antigen recognition sites, rather than using genetic recombination in the variable lymphocyte receptor gene.
An alligator is a large reptile in the Crocodilia order in the genus Alligator of the family Alligatoridae. The two extant species are the American alligator and the Chinese alligator. Additionally, several extinct species of alligator are known from fossil remains. Alligators first appeared during the Oligocene epoch about 37 million years ago.
Electroreception and electrogenesis are the closely-related biological abilities to perceive electrical stimuli and to generate electric fields. Both are used to locate prey; stronger electric discharges are used in a few groups of fishes to stun prey. The capabilities are found almost exclusively in aquatic or amphibious animals, since water is a much better conductor of electricity than air. In passive electrolocation, objects such as prey are detected by sensing the electric fields they create. In active electrolocation, fish generate a weak electric field and sense the different distortions of that field created by objects that conduct or resist electricity. Active electrolocation is practised by two groups of weakly electric fish, the Gymnotiformes (knifefishes) and the Mormyridae (elephantfishes), and by Gymnarchus niloticus, the African knifefish. An electric fish generates an electric field using an electric organ, modified from muscles in its tail. The field is called weak if it is only enough to detect prey, and strong if it is powerful enough to stun or kill. The field may be in brief pulses, as in the elephantfishes, or a continuous wave, as in the knifefishes. Some strongly electric fish, such as the electric eel, locate prey by generating a weak electric field, and then discharge their electric organs strongly to stun the prey; other strongly electric fish such as the electric ray electrolocate passively. The stargazers are unique in being strongly electric but not using electrolocation.
The Nile crocodile is a large crocodilian native to freshwater habitats in Africa, where it is present in 26 countries. It is widely distributed throughout sub-Saharan Africa, occurring mostly in the central, eastern, and southern regions of the continent, and lives in different types of aquatic environments such as lakes, rivers, swamps, and marshlands. In West Africa, it occurs along with two other crocodilians. Although capable of living in saline environments, this species is rarely found in saltwater, but occasionally inhabits deltas and brackish lakes. The range of this species once stretched northward throughout the Nile, as far north as the Nile Delta. On average, the adult male Nile crocodile is between 2.94 and 4.4 m in length and weighs 225 to 414.5 kg including stomach stones. However, specimens exceeding 6.1 m (20 ft) in length and weighing up to 1,089 kg (2,401 lb) have been recorded. It is the largest freshwater predator in Africa, and may be considered the second-largest extant reptile in the world, after the saltwater crocodile. Size is sexually dimorphic, with females usually about 30% smaller than males. The crocodile has thick, scaly, heavily armoured skin.
The American crocodile is a species of crocodilian found in the Neotropics. It is the most widespread of the four extant species of crocodiles from the Americas, with populations present from South Florida and the coasts of Mexico to as far south as Peru and Venezuela.
The star-nosed mole is a small mole found in moist, low areas in the northern parts of North America. It is the only extant member of the tribe Condylurini and genus Condylura, and it has more than 25,000 minute sensory receptors in touch organs, known as Eimer's organs, with which this hamster-sized mole feels its way around. With the help of its Eimer's organs, it may be perfectly poised to detect seismic wave vibrations.
Archosauriformes is a clade of diapsid reptiles that developed from archosauromorph ancestors some time in the Latest Permian. It was defined by Jacques Gauthier (1994) as the clade stemming from the last common ancestor of Proterosuchidae and Archosauria ; Phil Senter (2005) defined it as the most exclusive clade containing Proterosuchus and Archosauria.
The false gharial, also known by the names Malayan gharial,Sunda gharial and tomistoma, is native to Peninsular Malaysia, Borneo, Sumatra and Java. This freshwater crocodilian in the family Gavialidae is listed as Vulnerable on the IUCN Red List, as the global population is estimated at around 2,500 to 10,000 mature individuals.
Ampullae of Lorenzini are electroreceptors, sense organs able to detect electric fields. They form a network of mucus-filled pores in the skin of cartilaginous fish and of basal actinopterygians such as reedfish, sturgeon, and lungfish. They are associated with and evolved from the mechanosensory lateral line organs of early vertebrates. Most bony fishes and terrestrial vertebrates have lost their ampullae of Lorenzini.
Nitrifying bacteria are chemolithotrophic organisms that include species of genera such as Nitrosomonas, Nitrosococcus, Nitrobacter, Nitrospina, Nitrospira and Nitrococcus. These bacteria get their energy from the oxidation of inorganic nitrogen compounds. Types include ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB). Many species of nitrifying bacteria have complex internal membrane systems that are the location for key enzymes in nitrification: ammonia monooxygenase, hydroxylamine oxidoreductase, and nitrite oxidoreductase.
Mecistops is a genus of crocodiles, the slender-snouted crocodiles, native to sub-Saharan Africa.
Kenneth C. Catania is a biologist and neuroscientist teaching and conducting research at Vanderbilt University in Nashville, Tennessee. As an undergraduate, Catania worked as a research assistant at the National Zoo in Washington D.C. while attending the University of Maryland, College Park. In 1989, he received a BS in zoology from the University of Maryland. He received a master's degree (1992) and Ph.D. (1994) in neurosciences from the University of California, San Diego, working with Glenn Northcutt. He did his post-doctoral work with Jon Kaas at Vanderbilt University before joining the Vanderbilt Biological Sciences faculty in 2000 where he is currently a Stevenson Professor of Biological Sciences.
Iguanacolossus is a genus of iguanodontian ornithopod dinosaur that lived in North America during the Early Cretaceous period. It is known from UMNH VP 20205, the associated holotype with a large partial skeleton of a single individual.
David Jay Julius is an American physiologist and Nobel Prize laureate known for his work on molecular mechanisms of pain sensation and heat, including the characterization of the TRPV1 and TRPM8 receptors that detect capsaicin, menthol, and temperature. He is a professor at the University of California, San Francisco.
Most fish possess highly developed sense organs. Nearly all daylight fish have color vision that is at least as good as a human's. Many fish also have chemoreceptors that are responsible for extraordinary senses of taste and smell. Although they have ears, many fish may not hear very well. Most fish have sensitive receptors that form the lateral line system, which detects gentle currents and vibrations, and senses the motion of nearby fish and prey. Sharks can sense frequencies in the range of 25 to 50 Hz through their lateral line.
Christopher G. TateFRS is an English membrane protein biochemist and molecular biologist who works at the Medical Research Council Laboratory of Molecular Biology in Cambridge, UK. Tate is known for his contributions to the understanding of G protein-coupled receptors.
Kiyoshi Nagai was a Japanese structural biologist at the MRC Laboratory of Molecular Biology Cambridge, UK. He was known for his work on the mechanism of RNA splicing and structures of the spliceosome.
Pangalloanserae is a clade of birds defined in a 2001 study by Jacques Gauthier and Kevin de Queiroz as "most inclusive clade containing Galloanserae but not Neoaves". It contains crown Galloanserae as well as all stem-galloanserans.
