Unlike in some members of Chondrichthyes, in members of Osteichthyes they are covered by opercular flaps, and they generally work by the organism's pumping water from the mouth through them, where they facilitate oxygen and CO2 exchange.
They are the site of high in vivo expression of the inducible nitric oxide synthase gene, and parasites such as Pseudocycnidae can be found on them. The subclass Holocephali has only four pairs of them, while Thelodonti has eight. Unlike in some members of Chondrichthyes, in members of Osteichthyes they are covered by opercular flaps, and they generally work by the organism's pumping water from the mouth through them, where they facilitate oxygen and CO2 exchange. For 10 points, name these respiratory organs found in water-breathing animals such as tadpoles and fish.
They are the site of high in vivo expression of the inducible nitric oxide synthase gene, and parasites such as Pseudocycnidae can be found on them.
{gill}s