Difference between alligator and crocodile

Classification of the armored lizards

The order of the crocodiles or armored lizards (Crocodylia) comprises around 25 species. They are common in the tropics and subtropics of Africa, Asia, America and Australia. What they all have in common is that they are extremely well adapted to an aquatic way of life.

The first crocodiles lived in the Triassic over 200 million years ago. They have changed little since then. By the way: armored lizards are more closely related to birds - the last dinosaurs - than to any other reptile. Together they are the only survivors of the otherwise extinct group of archosaurs.

Traditionally, researchers divide the species of the order Crocodylia living today into three families, alligators (Alligatoridae), real crocodiles (Crocodylidae) and gavials (Gavialidae). Some zoologists believe that this classification cannot be justified because of the great similarities and summarize all species in a single family (Crocodylidae). In this case, the only difference between an alligator and a crocodile is the

Names.

Alligator and caiman form a family

The caimans and the two alligator species belong to the alligator family. With the exception of the Chinese alligator (Alligator sinensis), the representatives of the family occur only in the New World.

It is often said that alligators and caimans are smaller than real crocodiles. Many species of caiman are only two to three meters long, but pike alligator (Alligator mississippiensis) and black caiman (Melanosuchus niger) reach lengths of around six meters and are therefore larger than some crocodiles. For comparison: the African crocodile (Osteolaemus tetraspis) is a dwarf at 1.90 meters.

In many species, only the teeth of the upper jaw are visible when the mouth is closed. The surest difference between the family and the real crocodiles is to be found in the lower jaw. In all Alligatoridae, its fourth tooth fits into a pocket in the upper jaw and is therefore invisible when the mouth is closed.

Alligators can straighten their bodies surprisingly well on land and can reach considerable speeds when running. Most crocodiles, on the other hand, drag their bodies on land more or less clumsily across the ground. The snout of the alligator is broad and short, flattened and appears rounded. The appearance is therefore unmistakable. It is difficult to identify the caimans, who are all very similar.

At least the differentiation of the three different genera is possible for you as a layman: The black caiman is unique due to its size and color. The two genera of the smooth-fronted caiman (Paleosuchus) and the spectacled caiman (Caiman) differ in the nature of the forehead. It is without any elevations in the two smooth-fronted caiman species. The three spectacled caimans, including the northern spectacled caiman (also called crocodile kayman), have a web-like elevation between the eyelids.

The real crocodiles - the tooth makes the difference

The family of real crocodiles is mainly found in the ancient world, including the well-known Nile crocodile (Crocodylus niloticus). However, some representatives, such as the Cuban crocodile (Crocodylus rhombifer), are found in the New World and two species live in Australia. One of them, the saltwater or estuarine crocodile (Crocodylus porosus), is the largest species of armored lizards.

The snout of real crocodiles is usually longer and more pointed than that of alligators. The saltwater crocodile has two bony ridges that give it its name.

In contrast to a representative of the alligators, the fourth tooth of the lower jaw in the crocodile does not protrude into a pit, but fits into a groove in the upper jaw. It is therefore still visible even when the mouth is closed.

Like all members of the order Crocodylia, crocodiles care for their brood. The eggs in the nest are closely guarded by the female and protected from enemies. The mother helps with hatching and carefully carries her young into the water with her mouth. The sex of the young is not determined genetically, but rather by the temperature in the brood mound. Males hatch above 34 ° C and females at 30 ° C.

Gaviale - the nutrition specialists

The Gaviale family is a specialty. It only belongs to one species, the gharial (Gavialis gangeticus).

The seven-meter-long animal, also known as the real gavial, is probably best adapted to life in the water. Its limbs are short and hardly suitable for running on land. The snout of the gavial is extremely long and thin and has up to 110 pointed teeth - more than other crocodile species.

The Sundagavial (Tomistoma schlegelii), on the other hand, is a representative of the real crocodiles. It looks very similar to the gavial and, like the latter, has an elongated and thin snout and is therefore also known as the false gavial. The similarity is based on a phenomenon, the convergent evolution called. The similar way of life required a similar adjustment.

Genetic studies indicate that, contrary to traditional opinion, the Sundagavial belongs to the Gavialidae. Other researchers, however, argue for a union of crocodiles and gavials in a common family. The reason for this is the assumption that the Gaviale evolved from real crocodiles during the Cretaceous Period

The difference between an alligator and a crocodile is not always easy to tell. However, if you know that the fourth tooth of the lower jaw is a sure criterion for differentiation, you can differentiate accordingly the next time you visit the zoo.