Fill in the blank spaces appropriately in the table below:

Phylum/Class	Excretory organ	Circulatory system	Respiratory organ
Arthropoda	$...............$	$...............$	Lungs/Gills/Tracheal system
$...............$	Nephridia	Closed	Skin/Parapodia
$...............$	Metanephridia	Open	$...............$
Amphibia	$...............$	Closed	Lung

(N/A) The completed table is as follows:

Phylum/Class	Excretory organ	Circulatory system	Respiratory organ
Arthropoda	Malpighian tubules	Open	Lungs/Gills/Tracheal system
Annelida	Nephridia	Closed	Skin/Parapodia
Mollusca	Metanephridia	Open	Gills (Ctenidia)
Amphibia	Mesonephric kidneys	Closed	Lung

Explanation:
$1$. In $Arthropoda$,excretion occurs via $Malpighian$ $tubules$ and the circulatory system is $open$.
$2$. $Annelida$ are characterized by $Nephridia$ for excretion,a $closed$ circulatory system,and respiration through $skin$ or $parapodia$.
$3$. $Mollusca$ possess $metanephridia$ for excretion,an $open$ circulatory system,and respiration primarily through $gills$ $(ctenidia)$.
$4$. $Amphibia$ utilize $mesonephric$ $kidneys$ for excretion,have a $closed$ circulatory system,and use $lungs$ for respiration.