In most animals, the gut or digestive tract can be thought of as:

The gut or the digestive tract in most animals can be thought of as the tube that runs from the animal’s mouth to its anus. Hence, this tube transfers food to the organs of digestion. Moreover, this organ system takes in food, digests it to extract and absorb energy and nutrients and expels the remiaining waster as solid waste that is release from the body. 

tsd is temerature dependent sex determination.

tsd: it is a type of environmental sex determination in which the temperature experienced during embryonic/ larval development (ambient temperature for development) determine the sex of the offspring.

crocodile displays the tsd where the ambient temperature of the developing egg determines the individual's sex. for example in the american alligator's eggs, incubation at 33 ºc produces mostly males, while incubation at 30 ºc produces mostly females. so if the american alligator's egg will get the ambient temperature (33 degree celcius)during embryonic development from egg, the offspring will be male and same for the female sex determination.