SARCODINIDS(Amoeboid Protozoa)

These species are formerly group with the flagellates and some others in Phylum Sarcomastigophora.They generally contain a single type of nucleus.Contractile vacuoles are present, particularly among freshwater species.

Their body shapes range from completely amorphous and ever changing to highly structured, with elaborate, rigid skeletal supports.Most of them feed on small particulate material exclusively, although some house photosynthesizing endosymbiotic algae.They are free-living organisms.Some of them are parasites within the bodies of other parasites (hyperparasites).

They reproduce asexually, chiefly by binary fission or multiple fission. Some produce flagellated gametes which are usually involved in sexual reproduction Encystment is common, especially in freshwater and parasitic species, providing a means of withstanding unfavorable environmental circumstances.

Entamoeba histolytica- the causative agent of human amoebiasis, a very common protozoan disease

PHYLUM AMOEBOZOA

Individuals possess shapeless (“Amoeboid”) bodies, with wide, blunt (lobose) or thin pointy pseudopodia.Members of this phylum are called Amoebae.They are common in fresh water, moist soil and in the sea.They are all particle feeders and use their pseudopodia to capture food such as bacteria, other protozoan and unicellular algae.

Most species are naked, with the body surrounded only by a plasma membrane. This bodies are partially surrounded with a test or shell which can be a secretion product of the cell or may consist of a structured agglutination of fine sand particles or detritus.Amoebozoans use their pseudopodia to move and to feed. They flow into the advancing pseudopodium, a process called Cytoplasmic Streaming.

Their body is formless, lacking permanent anterior, posterior surfaces.Their ingestion involves phagocytosis, a process wherein lobopodia or filopodia advance on the intended prey, forming a food cup. The tips of the pseudopodia soon come together and fuse, thereby, internalizing the prey item. In pinocytosis, much smaller pseudopods are formed, capturing extremely small particulates or fluids rich in dissolved organic matter.

(AMOEBAE)

                                                                  

 

FORMS OF PSEUDOPODIA

Lobopodia are typical of the familiar amoeba.These are broad with rounded lips and bear a hyaline cap near each tip.

In contrast, filopodia,

lack a hyaline cap. They are very slender and often branched.

PHYLUM FORAMINIFERA

1 Individuals secrete multichambered test, generally of calcium carbonate; 2 Pseudopodia (reticulopodia) emerge through pores in the test and branch extensively to form dense networks.

These species are primarily marine and live on the bottom sediments as benthic organisms.

They feed on remarkable variety of food including other protist, small metazoans, fungi, bacteria and organic detritus. Some house photosynthesizing symbionts and others can take up dissolved organic material from seawater.

EXAMPLES OF THE DIFFRERENT TYPES OF FORAMINIFERAN SHELLS

(Calcareous foraminifera)

(Agglutinating foraminifera)

PHYLUM RADIOZOA

Body is divided into distinct intracapsular and extracapsular zones separated by a perforated membrane or capsule.Members of this phylum are called Radiolarians and Acantharians.They support their pseudopodia with thin, radiating microtubules that give a spiny, rayed appearance to many species.The pseudopodia and their micro tubular support are called Axopodia.

They possess a rigid endoskeleton, either of silica or strongtium sulfate.They are planktonic organisms.Many of them possess symbiotic algae and so meet at least some of their nutritional requirements through photosynthesis. They also feed as carnivores, capturing microscopic prey with the cytoplasm that flows along their axopods. Food vacuole formation and digestion occur in their extracapsular region; nucleus is contained in their intracapsular region.

RADIOLARIANS

PHYLUM HELIOZOA

Body is divided into distinct inner and outer regions, but the regions are not separated by any physical boundary.

Heliozoans bodies are demarcated into a frothy outer region of ectoplasm in which digestion occurs and a less highly vacuolated inner region of endoplasm containing the nucleus.

In some species, axopods function in locomotion and their microtubules located in the cores are apparently involved in mediating the changes in axopod length.

Heliozoans are primarily floating organisms with axopodia which serve primarily to capture food items.

FLAGELLATED PROTOZOANSThese species are characterized by the possession of a pellicle and one or more flagella.Most of them are free-living and motile.They exhibit nine pairs of microtubule ringing a pair of central microtubules over most of their length just like cilia.

Flagella are produced from basal bodies and their movement is believed to involve the sliding of microtubules in relation to each other. They often bear numerous mastigonemes along the length of the organelle. These mastigonemes increase the effective surface area of the flagellum, thus increasing the power that it can generate when it is moved through the water. Several wave movements may be initiated at the tip of the flagellum simultaneously, pulling the organism forward.Their locomotion can be fairly rapid, up to 200 um per second.

PHYTOFLAGELLATED PROTOZOANS

These species contain chlorophyll, obtain their energy directly from sunlight, and rely exclusively on carbon dioxides a carbon source.

They bear a stigma.

DINOFLAGELLATES

Cleistosphaeridium

Cribroperidinium

Kiokansium

Oligosphaeridium

Pseudoceratium securigerum

Florentinia

“Pyrodinium sp

Dinoflagellates are best known for commonly exhibiting bioluminescence and for occasionally producing highly toxic “red tide” . These are dense aggregations of certain dinoflagellates species whose neurotoxins kill fish and accumulate on certain warm-water fish causing “Ciguatera Poisoning” that can kill people that eat fish.

NOCTILUCA

These species lack chlorophyll and feed only as heteropthrops, ingesting particulate food through phagocytosis.

ZOOFLAGELLATED PROTOZOANS(Free-living Forms)

These species are free-living in either fresh or salt water.

They are sessile, being permanently attached to a substrate.

They bear a single flagellum, which extends for part of its length through a microvilli, in which food particles are ingested.

Most of them are colonial and immobile.

CHOANOFLAGELLATES

Are the most interesting groups of free-living species found primarily in fresh water. They represent an order of single-celled, transparent microbes that propel themselves with whip like appendages.

ZOOFLAGELLATED PROTOZOANS(Parasitic Forms)

About 25% of these species are parasitic or commensal with plants, invertebrates and vertebrates.

They often exhibit levels of structural and functional complexity.

Life cycles include adaptations for perpetuating the species from host to host.

They are covered with a single protein.

They possess a kinetoplast located within a single large mitochondrion.

TRYPANOSOMES(Phylum Saccostomae)

The human defense system recognizes this trypanosomes as foreign being and they are quickly phagocytozed by macrophages of the human Reticuloendothelial System.

LEISHMANIA DONOVANI

This causes extreme disfigurement and death wherein 12 million people are affected in many areas of the world.

TRICHOMONADS VAGINALIS

This is a small protozoan parasitizing the human vagina, prostate and urethra. It cause little or no discomfort in men, but it often produces considerable inflammation and irritation in women. The disease is readily transmittable, sexually and through contact with toilet seats and towel.

GIARDA LAMBIA

These species causes intense nausea, cramps and diarrhea in its human host. The infection is readily transmitted through drinking water contaminated with infected feces.

HYPERMASTIGOTES

These species are living commensally in the guts of termites, cockroaches and wood roaches.They are generally large.They are dependent between their host and flagellate.They are capable of digesting cellulose.

SOME CELLULAR FORMS

NAEGLERIA GRUBERI

This is a primitive protist that lacks mitochondria and typical golgi bodies and whose ribosome exhibit a number of prokaryotic features.They are commonly referred as Amoebomastigotes or Amoeboflagellates.

MYCETOZOA

Commonly known as the Cellular and Acellular Slime Molds.

Apparently, for some reasons, they are often been classified as plants or as fungi.

They exist as individual Amoeboid cells moving and feeding on particulate matter by means of lobopodia.