Small tt because there are large TT on the top
It is called the Rugae.
Rugae is a term used in anatomy to refer to a series of ridges produced by folding of the wall of an organ. For example the gastric rugae which allows for expansion of the stomach after the consumption of foods and drinks. The rugae of the vagina are the transverse ridges on the mucous membrane lining the vagina. They allow the vagina to stretch during childbirth.
Parasympathetic will return her heartbeat back to normal. This nervous system is responsible for regulating the body's unconscious actions, and stabilizes it.
One big reason for this is because individuals of the same species often have to fight over shared resources (this means shared food and shared environment).
Because they fight over a limited amount of space and food, competition between individuals within one species can be present and very tough.
On the other hand, having members of different species also possibly means different territories and different food sources. A lion has no quarrel with dolphins, while it can have a lot of fights with lions from different prides (large group of lions).