1. What cause eyes to be different colors?

The color of our eyes comes from the appearance of the pigment that is present in the iris, the central part of the eye. Brown eyes are rich in melanin pigment deposits, making them darker, while blue eyes lackmelanin. Heterochromia happens when the concentration and distribution of melanin isn't uniform.

Explanation:

Eye color is determined by genetics. The eyes can naturally change their color as a response to the iris expanding or contracting in the presence of light or as the iris ages. This results in the eyes gradually becoming darker or lighter in color.

thermophiles, notice the prefix thermo.

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.