I really don't know what you are refering to. The gills are covered by the operculum which are boney plates often called the gill plates. There is no thin membrane that I know of.
They are red because you can see the colour of the red blood through the thin walls of the gills. The gills carry the oxygenated blood into and around the fish just as your lungs do for you.
the water enters threw the gills oxygen from the water passes threw a thin membrane and into the blood stream carbon dioxide passes from the blood into the water in the gills so that means that the circulation system and the resportory system are working together
Capillaries
What happens when sound hits a thin membrane is that it vibrates the tympanic membrane. The tympanic membrane is also known as the eardrum.
It is a thin lining over the eye of a frog which gives it extra protection
plasma membrane
The cell membrane is the thin layer that holds cells together. Cell membranes are used as barriers and for protection.
I normally remove the gills. The gills, being very thin, are likely to burn. This can give you a gritty feeling when eating.
False
the membrane is called the mantel
tympanic membrane
respiratory membrane