Difference Between Alligator and Crocodile

Main Difference – Alligator vs Crocodile

Crocodilians, which include crocodiles, alligators, caimans, and gharials are the reptiles that first appeared on earth about 210 million years ago. Hence, this group is considered as one of the oldest groups that have lived on earth; they are known as ‘living fossils. At present, there are 23 living species of Crocodilians that belong to three Families namely; Alligatoridae, Crocodylidae, and Gavialidae. This extraordinary ancient group is considered as ‘keystone species’ because they play a vital role in maintaining structure and functions of the ecosystem by certain activities, which include selective predation, recycling nutrients, and surviving drought conditions. It is now believed that 18 species out of 23 are endangered due to various human activities, habitat loss and pollution of their habitats. Crocodilians are cold-blooded animals that only eat animal flesh. They are excellent swimmers due to the presence of short, strong legs and long powerful tails. Some common characteristics of crocodilians include the presence of dry, tough, scaly skin, which is heavily keratinized, strong well-ossified skeleton, large well-developed lungs, four-chambered heart, which is similar to that of birds and mammals, paired metanephric kidneys, which excrete nitrogen waste as uric acid, and shelled amniotic eggs. In addition, all the crocodilians show internal fertilization, by which sperms are inserted directly into the female reproductive tracts. Among the four different types of crocodilians, alligators and crocodiles are the biggest members that categorized under family Alligatoridae and family Crocodylidae respectively. These creatures look alike, but if we look carefully, we will be able to see the difference between alligators and crocodiles. The main difference between alligator and crocodile is their head shape; alligators have a U-shaped rounded snout whereas crocodiles have a V-shaped pointed snout. More details will be broadly discussed in this article. 

Alligator – Facts, Characteristics, and Behavior

Alligators belong to family Alligatoridae, which consists of two living species; American alligator and Chinese alligator. These creatures are restricted to freshwater habitats in the southern United States and eastern China. Adults are usually in the range of 18-4 m long and weigh about 360 kg with dorsoventrally flattened tail. Female adults are much smaller than males. Chinese alligators are smaller than American alligators. American alligators are found in Florida, Louisiana, Georgia, Alabama, Mississippi, South and North Carolina, East Texas, Oklahoma, and Arkansas, while Chinese alligators are restricted to Yangtze River Valley. Large male alligators are solitary and show territorial behaviors. Alligators have broad U-shaped snouts. Because of the overlapping upper and lower jaws, no teeth can be observed when the mouth is closed. Their eyes and nostrils are elevated from the skull. Because of this feature, alligators are capable of submerging their entire body except the eyes and nostrils. Their front feet have five toes, and hind feet have four toes with webbing. These webbings and their vertically flat tail, together make them excellent swimmers.  On the back side just beneath the skin, there are bony plates called osteoderms, which act as body armor. Alligator eggs are white, and their clutch size is 13-55. After laying eggs, female guards the eggs until hatching appear. However, this nest-guarding behavior may vary from aggressive defense to no attendance at all.

Difference Between Alligator and Crocodile

Crocodile – Facts, Characteristics, and Behavior

Crocodiles are categorized under family Crocodylidae and can be found in Africa, Asia, America and Australia. Crocodiles can be found in both saltwater and freshwater habitats. Their body sizes vary widely. The smallest dwarf crocodile is about 1.5-1.9 m while the largest saltwater crocodile is about 7 m in length. Adult males are much bigger than adult females. Females usually lay 7-95 eggs at one time and guard their eggs until hatching come out. The sex of hatchlings is not determined genetically but by temperature. Crocodiles have pointed V-shaped snout with narrow jaws. The width of their upper and lower jaws are approximately the same, hence, when the mouth is closed, upper and lower teeth get interlocked and can be seen clearly.

Main Difference - Alligator vs Crocodile

Difference Between Alligator and Crocodile

Shape of the Snout

Alligators have a U-shaped rounded snout.

Crocodiles have a V-shaped pointed snout.

Water

Alligators are primarily freshwater animals.

Crocodiles can live in freshwater and saltwater.

Shape of the Jaw

Alligators have wide jaws, and the upper jaw is wider than the lower jaw.

Crocodiles have narrow jaws and their upper and lower jaws are of the same size.

Placement of Teeth

Alligator’s upper teeth are visible when the mouth is closed

Crocodiles upper and lower teeth are visible when the mouth is closed.

Sounds

Alligators are not quite as crocodiles.

Crocodiles are much quieter than alligators.

Salt Glands

Alligators do not have functioning salts glands.

Crocodiles have functioning salt glands unlike alligators, thus, make them more tolerant to saline water.

Sensory Pits

Alligators have sensory pits only on the scales around their jaws.

Crocodiles have sensory pits in every scale on their body.Difference between Alligator and Crocodile- infographic

Image Courtesy:

“Crocodile” by jimmyweee – What a croc, via  

“Alligator” by Mielon – Own work, via

About the Author: Yashoda

Yashoda has been a freelance writer in the field of biology for about four years. He is an expert in conducting research related to polymer chemistry and nano-technology. He holds a B.Sc. (Hons) degree in Applied Science and a Master of Science degree in Industrial Chemistry.


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