Protozoans

at one time animal like protists where called protozoa which means ('first animal') and where classified separatly from plantlike protist. like animals, these organisms are heterotrophs. the four major phyla's are differed from one another from the way they move. as you will read further on zooflagellates is one of the phylums and the organisms in this group move swim with a flagella or long wiplike projections. another one of the phylums are the sarcodines which move by extensions of there cytoplasms. on the other hand ciliates move using a structure called cilia which are short hairlike projections. the final phylum that will be listed in this reading will be the sporozoans which unfortunatly do not move at all.

__Zooflagellates__
this is one of the many aquatic phyla and it propelle's itself by useing it flagella. for an organism to be put in this phylum it needs to have a flagella and needs to be able to move. most of these organisms have one or two flagella but a few organisms have many. two out of the many zooflagellates are shown below. these very strange looking organisms are generally able to absorb food through there cell membrane, and most live in lakes and streams to pick up decaying organic nutrients, and others are parasitic which means that they live inside other organisms and feed off the food that the larger organism supplies. most organisms in this phylum reproduce both sexually and asexually. in the asexual reproduction they use binary fission including mitotic cell division. in sexual reproduction which is when two gamets fuse and a new organism is made with different genetic material. Leishmania donovani Trichomonas vaginalis binary fission

__Sarcodines__
these very special organisms dont have any exterior help with moving but use there cytoplasms temporarily and extend it which is called pseudopods. these temporary extensions can be use not only for movement but also for feeding for they wrap there cytoplasms around the food and then encircle there prey and slowly digest.the best known sarcodine is the amoeba which is shown below.filaments at the leading edge, which subsequently will blend into one another to form networks. It is supposed that actin polymerization is at the origin of the force propelling the cell forwards.

amoeba eating

__Ciliates__
all the organisms in this phylum have a cilia or a hairlike projection similar to flagella. the intirior structure of cilia and flagella are identical. cilia works as an old rowing boat with thousands of oars. ciliates are another aquatic protozoa and are found in both fresh and salt water. next time you plan on going to swim in a lake or in your pool reconsider that there might be thousand of ciliates living inside.most ciliates are free living meaning that they are not parasitic or symbionts. Most ciliates feed on smaller organisms such as bacteria and algea.The food is moved by the cilia through the mouth pore into the gullet, which forms food vacuoles.Some ciliates are mouthless and feed by absorption, while others are predatory and feed on other protozoa and in particular on other ciliates.

__Sporozoans__
while most protozoans are free living others are parasitic. these nasty non-moving critters depend on other creatures or hosts to live.this phylum are parasites of a wide variety of organsims including worms, fish, birds, and humans. many sporozoans have a many complex life cycles that involve more than one host. this group of parasites reproduce in the sense of sporozoites. under the right condithion a sporozoite can attach itself to a host cell, penetrate it, and then live within it as a parasite. ____ SPOROZOAN __ __