The Crocodile Obsession of Michał Sitek | Venturing to say that the last living bridge between the present time and prehistory are crocodiles – is not enough. Research shows that, in fact, the direct ancestors of the reptiles appeared more or less 80 million years ago. However, they only derive from animals inhabiting our planet with dinosaurs.

My travels abounded in encounters with these reptiles. I can say that with each successive contact with them my fascination grew. Now – which I can say with a clear conscience – each consecutive expedition is subordinated to my crocodile “obsession”. “The ancestors of crocodiles have a fascinating history, which is relatively little known compared with the history of dinosaurs. They were completely different creatures from those that we know today, much more diverse. Our research shows that they had very high adaptability” – Tom Stubbs from the University of Bristol believes. And it is this adaptive potential that allowed the crocodiles to survive, and for ourselves, it made it possible to enjoy their beauty.

---

 

The individual families differ from each other in the tooth system. In alligators, 40 mandibular teeth hide in the tooth crevices of the upper jaw. In the Nile crocodile, the fifth tooth is positioned in the upper jaw, and the fourth tooth in the lower jaw – these are the largest teeth. With the mouth closed, these fangs go into special recess in the maxilla and the mandible. The biggest teeth – the fours, go into deep sinuses in the intermaxillary bone. Gavials have 51 teeth of the same shape and size, of which 24 in the maxilla and 27 in the mandible. Their palate is firm and separates the nasal cavity from the mouth cavity. The crocodile tongue is fixed to the floor of the mouth cavity.

The back is covered with 4-6 rows of horn discs, the highest of which continue to the upper edge of the tail which is strongly laterally flattened. The body is ended with a strongly developed and muscular tail, which provides a kind of a drive during swimming. Two pairs of short, strong legs, whose front fingers are free and the rear ones are wholly or partially webbed. In contrast to other reptiles, they can produce loud sounds. Crocodiles grow up to 6 m in length (as counted from the head to the tail) and reach up to 750 kg in weight. Of course, bigger “specimens” do happen. Their life span can be as long as 60 years.

The mating season in crocodiles is dependent on the climate conditions. Temperature has the greatest impact on species living in temperate climates. In animals living in the hot zones, in turn, the advent of the dry season has the biggest influence. Each species of the crocodile family is oviparous. The crocodile reaches its sexual maturity at the age of 7 years, with a body length of over 200 cm.

Their courtship looks interesting. The male rises water fountains into the air by making vigorous movements – he hits the water surface with the tale, while letting air bubbles from his mouth. The copulation lasts for about a minute. After roughly one month, the female lays eggs on the land. After building a mound (the material being sand, mud, leaves and plants) or digging a cavity in the sand, she lays eggs (in the number of 30 to 70) (every half a minute) and covers them with a layer of vegetation. The process of incubation is influenced mainly by the temperature. A piece of information worthy of noting is the aggressive maternal instinct of the female, which is a unique feature among reptiles. An intruder appearing near the nest has to take into account serious consequences.

The incubation process takes about 3 months. The crocodile sex depends on the temperature to which the eggs are exposed – if the average temperature in the nest ranges between 32 °C and 34.5 °C, then males will hatch out. If the temperature is either lower or higher – females will be born. At this time, the female takes care mainly to wet the eggs. The mother passes urine onto them or sits down on them immediately after going out of the water. It happens that the female does not eat virtually anything during this period, using the fat deposited in her tail and fingers to satisfy the hunger. Being ready to hatch, the young make indicating sounds.

To break through the egg shell, the young use the so-called egg tooth. The mother digs out the nest and takes the young in her mouth to the water, where they are able to swim right away. Most of young crocodiles become victims of other predators, leaving the average number of surviving specimens being about three. Their length ranges from 20 to 30 cm. In some species, cannibalism was found among males. Initially, young crocodiles feed on arthropods and as they mature, their menu starts to include molluscs, crustaceans, fish, reptiles and amphibians. One year after hatching, their size is already two times larger, and after a further 6 months they begin to move away from the reservoir. They leave their nursery permanently after 3 years.

Generally, food for crocodiles can be anything that will appear within the reach of their jaws. Starting from birds through to mammals. They won’t scorn carrion and smaller individuals of their own species, either. Due to their considerable size, their victims can be even adult antelopes or smaller elephants. In practice, a smaller-size prey is swallowed alive. Larger victims, in turn, after being tracked down, captured and drowned, with quick movements of the head are rent into parts that can be swallowed. Crocodile teeth are not sharp enough to dismember a meal, they are mainly used to hold down the victim. After killing a victim, the crocodile makes a rapid movement around its own axis with the aim of dismembering the victim’s body. When hunting for fish, the crocodile drives the fish to the shoal and then swallow them in whole – the head forward, so that the gills do not slash its throat.

When attacking, a crocodile can reach a speed of up to 120 km/h. The Nile crocodile has acquired a distinctive feature, that is the high endurance of the lack of food. They are able not to eat for several months. Crocodiles have also become an object of worship. They were among animals worshipped in ancient Egypt. Sobek – the Egyptian god of fertility and water had the head of a crocodile. It was in honour of these reptiles that the city of Crocodilopolis was founded. In some parts of the world, mummies of these reptiles were buried together with the bodies of high-ranking people. Indigenous Australians used to believe, in turn, that one of the biggest rivers was formed by the “act” of a crocodile, which created the river bed after chewing up the land.

Crocodiles live mainly in freshwater. They inhabit large lakes, rivers and vast marshy lands, and more rarely – the sea estuaries and coastal areas. There are also species that occur in salt water. Their proper habitat is water; they are rather reluctant to come ashore. Among crocodiles, the following species are distinguished: the rosary, the American, the Nile, the marsh, the New Guinea, the Orinoco, the Siamese and the short-mouthed crocodiles.

The crocodile heart and muscles enable the slowed-down flow of blood and the closure of the otic and nasal openings, which allows a prolonged immersion in the water. During diving, the pulmonary blood circulation is switched off by opening a hole in the aorta. The Nile crocodile is able, e.g., to hold its breath for 45 minutes. Sometimes these crocodiles are lying immersed in water for hours, and only their eyes and nostrils can be seen above the water surface. During the day, they lie in the sun; they slow down their breath, and their heart begins to beat slower. This is their rest time, where their vital functions slow down, whereby they save a considerable amount of energy. At that time, they can often be found with open mouths. The crocodile body of the is thus cooled, while any food waste is pecked out from the crocodile’s mouth by birds that live in symbiosis with it. In the case of the Nile crocodile, this cooperation involves the cleaning the crocodile’s mouth from residues and parasites by the Spotted squeaky, which feeds this way. Species living in very hot areas protect themselves against heat by burying themselves in silt and falling into a deep sleep. On land they move slowly and sluggishly; however, they are able to sharply accelerate suddenly. It is in the water that they exude energy, and there they mainly feed.

In northern Australia live crocodiles which have adapted themselves for living in salt water. Fairly often they can be found in the ocean. Those that have the ability to live in sea water, can cover even up to 5 thousand km during their migrations. According to the information obtained by Australian researchers, crocodiles can cover that long distances by using ocean currents. These reptiles can “surf”, as they put it. This fact can explain their presence on the islets situated far away from the continent.

Crocodiles have virtually always been the object of desire of hunters, due to their tasty meat and precious skin, which is used for the manufacture of a range of valuable accessories. Demand for crocodile skin is still very common, still making these reptiles a tasty morsel for all sorts of cruel men. The price offered for it reaches an imposing height, which makes such a great temptation that not only older specimens, but also mothers with their offspring are killed. The opinion that the civilization development of humankind is their biggest enemy is not unfounded.

Deforestation, land reclamation and building dams on rivers all significantly contribute to the reduction of the population of these fascinating animals. They were also eradicated by indigenous inhabitants due to the fact of being dangerous to humans. The dreadful reputation they have might be proved by the panic triggered by the 15 thousand crocodiles that escaped from a breeding farm in South Africa during a flood in 2013. In north Africa, virtually all crocodiles have been killed off from their habitats. It is very likely that the Indian gavial does not occur in the wild at all, even though once the rivers abounded in this species of reptiles.

Currently, crocodiles under protection in every region of the world. This increases their chance of survival.

photo. Better safe than sorry It seems that my passion is a one-man activity. No always. To make a unique shot, a companion is sometimes needed, who will lend a helping hand to get away in one piece from an oppression.

photo. Sometimes you have the upper hand It is a risky passion – I can say this with a clear conscience. But close encounters with huge crocodiles offer me a pure pleasure. Perhaps this isn’t too safe, but what can stop the real man of passions?