Protozoa-Phyla Rhizopoda, Biology tutorial

Protozoa-Phyla Rhizopoda (Amoeba) Apicomplexa (Plasmodium)

Characteristics of Phylum Rhizopoda (Sarcodina):

These have the common features of protozoa. Sarcodinians have fundamentally bare surface without any discrimination. It is the phylum of free living protozoans. They have apparently plain structure. They have the odd form of locomotion (by streaming protoplasm) that is one of the most characteristic features. Characteristically they have both external and internal skeletal structures of the mineral nature. Amoeba is only exclusion to the skeletal structure.


It is found in bottom of ponds. It can reach .025cm and may simply be visible to naked eye as a white speck. Under microscope, there is a clear outer ectoplasm and the granular jelly-like mass of protoplasm. There is the intense nucleus in endoplasm. It is enclosed by fine membrane. There are also bigger particles -remains of amoeba's food, surrounded in food vacuoles in endoplasm. Food and water enclosed by pseudopodia form food vacuole. Food substance of amoeba are generally diatoms. Amoeba has no permanent shape. Its shape is continuously varying as it pushes lobes of its protoplasm (known as pseudopodia or false feet) in different directions. Amoeba in direction to which it expands its pseudopodia by pulling rest of the protoplasm from behind towards pseudopodia formed.

The amoeba also has large clear vacuoles having liquid called contractile vacuoles. The vacuoles slowly expand until they burst open to discharge the content when they reach the certain size. This is the technique by which controls bodily ionic content.

The most significant element of the amoeba might be pseudopod. Psuedopod is utilized to assist amoeba travel, and also to consume. It is the part of amoeba's body which it can elongate and drag itself with. To eat, amoeba widens out pseudopod, encloses the piece of food, and pulls it into rest of amoeba's body.

Amoebas reproduce to create more amoebas by process known as binary fission. This signifies that 1 amoeba can divide in half and create 2 alike new amoebas. Amoebas consume bacteria, algae other protozoans, and small elements of dead plant or animal matter.

They spend most of the time attached to bottom or to plants. At times they float freely in water. They perform this as the swarm. All amoebas of same species will unattached from base or plants and float around until they land in novel place and re-attach. Animals which eat amoeba comprise plankton feeders, like mussels and water fleas.

Life Processes:

Respiration and excretion happen by diffusion through general body surface. Dissolved oxygen and carbon dioxide is switched between animal and adjoining water by diffusion. Similarly inside organism, gasses and nutrients diffuse through to every parts of animal. New protoplasm is sensitive to environment although amoeba has no sense organs. It will withdraw from the dilute acid or alkali solution. It will as well extract its pseudopodia if touched with the needle or weak electric current is passed by water in which it has. It develops by absorbing the food nutrient to create new protoplasm until it is approx .025cm in diameter. It then splits by binary fission. In procedure of binary fission, nucleus turn into elongated constricts and centre then splits into two. Then adjoining protoplasm similarly splits into two.

Every protoplasmic mass surrounds the nucleus. If pond in which amoeba lives dries up, amoeba withdraws its pseudopodia, develops into round and forms cyst around itself until when it is favorable again. Cyst bursts when it is wet again and amoeba then develops into active again. At times within cyst, animal splits into small portions each having a part of nucleus. These are then called spores that become small amoeba when water comes.

Phylum Apicomplexa (Sporozoa):

Plasmodium, generally called as malaria parasite, is the large genus of parasitic protozoa. As with few other genera of clinically significant microorganisms, genus name also yields the common noun; therefore species of genus are called as plasmodia. Infection with plasmodia is called as malaria, the deadly disease common in tropics. It now has approx 200 species separated into numerous subgenera; as of 2006 taxonomy was changing, and species from further genera are probable to be added to Plasmodium. At least 10 species infect humans; other species infect animals, comprising birds, reptiles and rodents, where as 29 species infect non-human primates.

The protozoa in phylum Apicomplexa have the pellicle and so cells have the definite shape. This is dissimilar what have in sarcodinans that have no definite shape. They have no pellicle. Their major distinctive feature is production of spores during sexual and asexual reproduction. The example of sporozoa is malaria parasite, Plasmodium. There are 4 species of the sporozoan. Only two of them cause malaria fever. Parasite is inserted into body of mammal when vector, female annopheline mosquito infected with parasite goes to feed on man. It pours out plasmodium parasites along with the saliva into blood stream of man. It enters blood and is carried round body where it affects different organs particularly the liver. Here it multiplies and infect liver cells until they finally leaves lever, enters red blood cells. They then form gametocytes, when infected human blood is sucked up by mosquitoes. In stomach of mosquito malaria parasites plasmodium, escape being digested. Eggs are fertilized to form zygote that bores through wall of stomach of mosquito and finds its way back into salivary gland of mosquito to begin cycle again. Infected mammal suffers from stopping fever at intervals that coincide with time parasites multiply in blood.

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