The nile crocodile
The Nile crocodile (Crocodylus niloticus) is Africa’s largest crocodilian species and can reach a maximum size of 6 meters (Fergusson. R.A. 2010) and weigh up to 730 kilograms. However, the average C.niloticus grows to roughly 5 meters in length and weighs approximately 225 kilograms. Crocodiles are sexually dimorphic and so the male Nile crocodile grows up to 30% larger than the female. The largest accurately measured male C.niloticus, killed in Tanzania, measured an incredible 6.45 meters long and weighed roughly 1090 kilograms. C.niloticus is dark-brown in colour, with black spots on its back and tail as well as purple spots on its yellowish underbelly. Its colouration helps it hide and stay camouflaged from its prey. When in the water, they can swim at fast speeds by moving their bodies and tails in a sinuous manner where they can sustain a speed of 30 to 35km per hour. C.niloticus has a particular preference for darker, murky waters as these are advantageous for the crocodiles hunting behaviour.
Crocodiles, like most reptilian species, are ectothermic and thus rely on external heating for warmth and survival. Therefore by extension, it can be concluded that crocodiles will be more active in the warmer summer months and fairly lethargic during the cooler winter months. A study by Wallace and Leslie 2008 proved that juvenile C.niloticus had relatively emptier stomachs during the winter months in comparison to the summer months proving that this species was more energetic during the warmer period. A further study conducted by Seebacher and Grigg in 1997 found that crocodiles that thermoregulated during different seasons, preferred body temperature correlated with changes in water temperature concluding that crocodiles are more frequent in warmer, tropical waters.
C.niloticus lead a diurnal lifestyle however they are predominantly active after dusk. During the day crocodilians illustrate a range of behaviours including basking, moving between land and water
Crocodiles, like most reptilian species, are ectothermic and thus rely on external heating for warmth and survival. Therefore by extension, it can be concluded that crocodiles will be more active in the warmer summer months and fairly lethargic during the cooler winter months. A study by Wallace and Leslie 2008 proved that juvenile C.niloticus had relatively emptier stomachs during the winter months in comparison to the summer months proving that this species was more energetic during the warmer period. A further study conducted by Seebacher and Grigg in 1997 found that crocodiles that thermoregulated during different seasons, preferred body temperature correlated with changes in water temperature concluding that crocodiles are more frequent in warmer, tropical waters.
C.niloticus lead a diurnal lifestyle however they are predominantly active after dusk. During the day crocodilians illustrate a range of behaviours including basking, moving between land and water
References: Barr. B. 1997. Food Habits of the American Alligator. Alligator mississippiensis in the Southern Everglades. Unpublished. Ph.D. diss. University of Miami, Coral Gables, Florida. Fergusson. R.A. 2010. Nile crocodile Crocodylus niloticus. 84- 89 in Crocodile. Platt. S.G., Rainwater. T.R., McMurry. S.T. 2002. Diet, gastrolith acquisition and initiating of feeding among hatchling Morelet’s Crocodiles in Belize. Herpetological Journal. 12:81-84. Seebacher. F., Grigg. G.C. 1997. Patterns of Body Temperature in Wild Freshwater Crocodiles, Crocodylus johnstoni: Thermoregulation versus Thermoconformity, Seasonal Acclimatization, and the Effects of Social Interactions. Copeia. 549-557. Tucker. A.D., Limpus. C.J. McCallum. H.I., McDonald. K.R. 1996. Ontogenetic dietary partitioning by Crocodyus johnstoni during the dry season. Copeia 1996: 978-988.