It is hard to believe that crocodiles, those fearsome and powerful reptiles that sit, camouflaged, at the water's edge and devour anyone who gets too close, were once tiny babies just hatched.
In AnimalWised we explain the crocodile incubation process for all those who want to know more about the birth of these impressive animals. We will describe the environment of the crocodile, the ideal temperature for the development of fetuses in the egg, how long the incubation lasts and much more.
How does the crocodile reproduce?
The so-called crocodiles are those reptiles that are included within the Crocodylidae family, which currently includes 14 species. Some of the best known are the American crocodile (Crocodylus acutus), the Mexican crocodile (Crocodylus moreletii) or the Nile crocodile (Crocodylus niloticus).
Crocodiles are oviparous reptiles: after fertilization (which is, in their case, internal), they lay eggs in nests built with branches, as birds do. However, unlike these, crocodile nests are located on the ground and the eggs are buried. Thus, they are not incubated thanks to the body heat of their parents, although the female usually stays close to the nest to protect her offspring.
Type of crocodile reproduction
The reproduction of crocodiles is of a sexual nature The couple copulates in the aquatic environment and can be repeated for several days. After mating, internal fertilization will take place in the female and, later, the laying of eggs.
Crocodile sexual maturity
Crocodiles can reproduce when they reach sexual maturity, that is, when their sexual organs are fully developed. When does this occur? Although it may vary according to the species, it is estimated that females are sexually mature from the age of 11old, while males reach sexual maturity at 16 years old about.
How do crocodiles choose mates?
During the reproductive season of crocodiles, there are frequent fights between the males, who must expel competitors from their territory who could conquer the female and take away their opportunity to reproduce.
Once the male and female meet, courtship begins, during which the male crocodile tries to seduce the female demonstrating its reproductive quality through a colorful display: it emits sound vocalizations, as well as infrasounds that are inaudible to us. It can also hit the water with its snout or move its body in repeated undulations. It is also typical that he swims in circles around the female. If the female is receptive, she raises her snout in acceptance, and then mating takes place. After fertilization, the male will continue on his way, while the female will look for a suitable place to lay her eggs.
Crocodile incubation period
The reproductive season of the crocodile is different for each species according to its geographical location. For freshwater crocodiles, it takes place during the dry season, which is equivalent to summer in the southern hemisphere and winter in the northern hemisphere. In contrast, s altwater crocodiles breed in the wet season.
How long is the incubation period for crocodiles? The crocodile's incubation time varies depending on the species, but usually around 3 months As we will explain below, this period can be lengthened or shortened, in addition, depending on the environment in which this unique phenomenon takes place.
Crocodile Incubation and Environment
The crocodile incubation process is greatly influenced by the environment in which it takes place. Of all the ecological factors that can influence the development of crocodile embryos under the shell, the temperature of the soil surrounding the eggs (since they will not be incubated by the warmth of their parents' bodies) has the highest impact on this phenomenon. This temperature can affect the incubation time, which slows down as the temperature decreases, and can reach up to 110 days. On the contrary, the incubation period is shorter at high temperatures, which may favor its reduction to a minimum duration of approximately 85 days.
The ideal temperature range for embryo development is different for each species, but it usually ranges between 30 and 34 ºCTemperatures below 25ºC and above 35ºC can cause abnormalities in the offspring, if not death.
Surprisingly, temperature is also responsible for the sex of offspring. Generally, warm temperatures (above 31°C or so) will produce male crocodiles, while if incubation has taken place at temperatures below 31°C, it will be females that break through the calcareous walls of the eggs.
The effect of pollution on crocodile incubation
And speaking of shells: it has also been proven that the presence of contaminating substances in the crocodile's incubation medium deteriorates the composition of the egg, which becomes unviable as the shell is too fragile. It is organochlorine compounds, such as DDT, that produce this effect.
Where do crocodiles lay their eggs?
Of the two crocodile parents, the female is in charge of finding the ideal place to lay her eggs. Once fertilization has taken place, a meticulous search stage begins: the females explore their surroundings until they discover an area that enjoys the appropriate environmental conditions for crocodilian embryonic development. In addition, the location of the future nest must be protected against possible predators and against floods, since the laying of eggs takes place in the vicinity of bodies of water such as rivers or lakes.
It is not always easy for them to find the perfect corner to build a shelter for their offspring. In fact, mothers-to-be may even choose a site to abandon later, realizing that it is not good enough for the proper development of their babies.
How many eggs does a crocodile lay?
Although the species of crocodile also influences this aspect, in general, the female usually lays between 40 and 90 eggs.
Birth of the Crocodile
Unlike sea turtles, who are forced to find their way to the sea on their own once they hatch, little crocodiles need their mothers to take their first steps in the new world by who have just arrived. Just before hatching, they make sounds from inside the shell. The mother, who stays near the nest throughout the incubation period, hears them and proceeds to dig up the nest so her young can come out Some species of crocodiles, as is the case of the Johnston's crocodile (Crocodylus johnstoni) they even help them to break the shell. The young, on the other hand, have a hard and pointed structure, located in their snout, which is called "egg tooth". They use it to break the shell from within. When the little crocodiles manage to evacuate the egg, They are carried into the water in their mother's mouth
Although baby crocodiles need their mother's help to hatch, they are very independent once they hatch and can walk, swim and get around with ease. Even so, they open their eyes to a world full of predators: large carnivores stalk crocodile nests to devour the young and, despite their mother's efforts to protect them, the mortality rate of hatchlings is very high and it reaches 99% in some species.
The high mortality rate of newborn crocodiles is one of the reasons why some crocodile species, such as the Orinoco crocodile (Crocodylus intermedius), the Cuban crocodile (Crocodylus rhombifer) or the Philippine crocodile (Crocodylus mindorensis), are in serious danger of extinction. Their young suffer a high degree of predation, both by other animals and by humans. These small crocodiles are frequently slaughtered in their nest to prevent the reproduction of an animal that is considered a danger to humans. As they grow older, they risk becoming the raw material for “glamorous” accessories such as crocodile-skin belts, bags and shoes, or falling prey to hunters who pay for guided safaris to stalk them for fun. Although the hunting of the most endangered species is prohibited, the illegal killing of crocodiles continues to be practiced, as there is still a demand for crocodile meat or products made from their skin. Our society needs to learn to dispense with its whims and report these crimes, so that even more tiny newborn crocodiles have a chance to grow into the formidable animals they are destined to be.
If you want to know more about these incredible animals, don't miss this other article: "Crocodile feeding".
