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hi

My son is doing a school project on Crocodiles and he has asked me about the reproductive system, and whether crocodiles excreete through the same hole as they lay their eggs through.

I am having a real hard time finding anything on the web about this proceedure could anyone help me?

thanks

John

Im no croc expert as i just have lizards and such but from what i remember from HS Biology that crocs have the same basic body plan as other lizards, meaning that the do have seperate places to HOLD wastes and eggs, there is only one opening, called the cloaca.
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~David - KDRKreatures
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Yes, reptiles, amphibians, and birds all have one common external opening, as mentioned, the cloaca, serving both excretory and reproductive purposes. It is we mammals that are the oddballs, here.

Is your kid interested in any aspect of its physiology?

What is perhaps most unique about crocodilian physiology, compared to other herps, is their heart.
Even though they are one of the most archaic of the reptilia, crocodylians have many derived traits that occasionally place them closer to mammals and birds, than to other reptiles, including a 4-chambered heart. This heart, like those of birds and mammals, allows complete separation of oxygenated and deoxygenated blood. This allows for for two separate pressures to be present in the heart at any one time. A high pressure for the body and a low pressure for the lungs. For most tetrapods this is the "goal" of a heart. It allows for fast circulation throughout the body, thus maintaining cells full of nutrients, while low pressure circulation goes to the lungs so as not to explode the alveoli. In chelonians and lepidosaurs, this separation is done through physiological (instead of mechanical)means, since they have only 3-chambered heart.

Anatomically divided hearts seem to allow for higher pressures, while physiologically divided ones seem to allow for longer times without oxygen. I don't know if this is studied to any great extent. They do know that the crocodylian heart is one of the most hydrodynamically efficient hearts known to science, it even has a valve that allows their hearts to close off blood flow to the lungs (which are useless while underwater).

There are various websites that talk aobut this, just do a search on dogpile.com

Renee