Of the 23 species of crocodilians alive in the world today, three are seen in India. They are Gharial (Gavialis gangeticus); Estuarine crocodile (Crocodylus porosus) and Mugger or Marsh crocodile (Crocodylus palustris). Estuarine or Saltwater crocodile (locally known as ‘Baula kumbhira’) belongs to the kingdom Animalia in the phylum Chordata, Sub – phylum Vertebrata, Class Reptilia, Order Crocodylia, Sub-order Eusuchia, Family Crocodylidae, Sub-family Crocodylinae.
An adult female Saltwater crocodile builds a mound nest, typically of about 1.5 1.8 m (5-6 ft) diameter and -1-1.2 m (3-4 ft) high. These raised structures are composed of mud combined with dry leaves and twigs of Hental (Phoenix paludosa), Kharkhari (Acrostichum aureum), Nalia (Myriostachya wightiana) that generate heat for incubation of the eggs.
Saltwater Crocodiles build a mound nest of mud combined with dry leaves and twigs of mangrove plants available in their surroundings. After laying the eggs, the mother crocodile guards the eggs vigilantly. During the incubation period, if someone approaches the nest, she attacks the intruder. Crocodiles lay two types of eggs-Fertile and Infertile. It has been observed that crocodiles also guard nests containing infertile eggs.
When it is time for the eggs to hatch the mother crocodile helps the hatchlings to emerge by breaking the egg shell. The hatchlings recognize the call of their mother and make squeaking sound in the nest.
The mother takes out the hatchlings by removing the nest mound materials and takes them to wallow waters for feeding. Some crocodiles carry their hatchlings in their mouth and take them to narrow channels.
Temperature and moisture play key role to determine the gender of the embryos during the incubation period. Optimum temperatures (31.5°C -33°C or 89°F -95.5°F) produce males & females in equal numbers.
When in danger, hatchlings make a squeaking noise, hearing which the adult crocodiles (both male and female) rush to protect them. Among wild animals, this kind of intensive maternal care is unique and rare,
Being ectothermic (body temperature is dependent on the surrounding environment), crocodiles lose body temperature during the cool hours of the night. Hence, they come out of the water, during the day for basking on the banks, and gain back the lost temperature. They primarily live on fish diet. They are opportunistic predators. Their approach is initially slow, being totally submerged with only eyes, ears and nostrils showing above the water surface. As the prey is within range, it submerges completely until it reaches within 2-3m of its prey. The actual attack is sudden and it uses its mouth and muscular tail to drag the victim into water.
Read the full story that first appeared in Wild Watch here:
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