Sarcodina have pseudopodia for locomotion. They also engulf food particles and live in fresh water, sea water or moist soil. Pseudopodia can be of different types such as lobopodia, axopodia, filopodia and reticulopodia. They are uni nucleate and have holozoic mode of nutrition. Unlike zooflagellate they are monomorphic. They have sexual as well as asexual mode of reproduction. Asexual methods include fission, budding and spore. While sexual methods include syngamy. It includes amoeba, entamoeba, pelomyxa and radiolarians.
Amoeba proteus: Russel von Rosenhoff discovered it. They reside in fresh water. Lobopodia are the main means of locomotion. They have contractile vacuole which is very well surrounded by mitochondria. Cytoplasm is divided into endoplasm and ectoplasm. Endoplasm is further sub divided into plasma gel and plasma sol. They have holozoic mode of nutrition. The mode of sexual reproduction is controversial. They ingest food material in different ways such as import (passive), invagination (a tube to digest food articles), circumfluence and circumvallation (active prey). The working of contractile vacuole depends on the medium in which it is placed. It works faster when contractile vacuole is placed in distilled water. However, when it is placed in salt water it works slower. Hyman gave the sol gel theory regarding amoeboid movement.
Pelomyxa is a giant amoeba which occurs in fresh water. It depends on diatoms for its food substrate and has holozoic mode of nutrition. They are multinucleate with both contractile and non contractile vacuoles. Fission and gamete formation are asexual and sexual methods of reproduction respectively.
Entamoeba histolytica: It was Losch who discovered it. They have single host in their life cycle and are known as mono-genetic. They cause amoebic dysentery and reside in the large intestine of human being. Abdominal pain, recurrent motions are there main features. Pseudopodia are their means of locomotion. They have no contractile vacuoles and RBCs provide as means of food. They divide by binary fission. Entamoeba has two forms magna and minuta. Magna is found in mucosa and form ulcers. Minuta is found in lumen and does not cause any disease. Metragyl is the most important drug against amoebiasis.
