Which protist group is made up of decomposers

Various organisms with a protist-level organization were originally treated as fungi, because they produce sporangia, structures producing and containing spores. These include chytrids, slime molds, water molds, and Labyrinthulomycetes. Many of these organisms were also treated as fungi due to a similar environmental role: that of a decomposer.

These fungus-like protist saprobes are specialized to absorb nutrients from nonliving organic matter, such as dead organisms or their wastes. For instance, many types of oomycetes grow on dead animals or algae.

Saprobic protists have the essential function of returning inorganic nutrients to the soil and water. This process allows for new plant growth, which in turn generates sustenance for other organisms along the food chain. Chytrids can be single or multi-cellular. There are about one thousand species, most living in water or soil. Most are decomposers.

Some are parasites and can cause diseases in plants, including corn, alfalfa, and potatoes. It is one reason why protist classification is so challenging. The supergroups are believed to be monophyletic; all organisms within each supergroup are believed to have evolved from a single common ancestor, and thus all members are most closely related to each other than to organisms outside that group. There is still evidence lacking for the monophyly of some groups.

Many protists are pathogenic parasites that must infect other organisms to survive and propagate. Protist parasites include the causative agents of malaria, African sleeping sickness, and waterborne gastroenteritis in humans.

Other protist pathogens prey on plants, effecting massive destruction of food crops. Members of the genus Plasmodium must infect a mosquito and a vertebrate to complete their life cycle. In vertebrates, the parasite develops in liver cells and goes on to infect red blood cells, bursting from and destroying the blood cells with each asexual replication cycle [Figure 4].

Of the four Plasmodium species known to infect humans, P. In , it was estimated that malaria caused between 0. During the course of malaria, P. In response to waste products released as the parasites burst from infected blood cells, the host immune system mounts a massive inflammatory response with delirium-inducing fever episodes, as parasites destroy red blood cells, spilling parasite waste into the blood stream.

Techniques to kill, sterilize, or avoid exposure to this highly aggressive mosquito species are crucial to malaria control. This movie depicts the pathogenesis of Plasmodium falciparum , the causative agent of malaria.

The glycoproteins are identified by the immune system as foreign matter, and a specific antibody defense is mounted against the parasite. However, T. In this way, T. Without treatment, African sleeping sickness leads invariably to death because of damage it does to the nervous system. During epidemic periods, mortality from the disease can be high.

Greater surveillance and control measures have led to a reduction in reported cases; some of the lowest numbers reported in 50 years fewer than 10, cases in all of sub-Saharan Africa have happened since In Latin America, another species in the genus, T. The parasite inhabits heart and digestive system tissues in the chronic phase of infection, leading to malnutrition and heart failure caused by abnormal heart rhythms.

An estimated 10 million people are infected with Chagas disease, which caused 10, deaths in Protist parasites of terrestrial plants include agents that destroy food crops. The oomycete Plasmopara viticola parasitizes grape plants, causing a disease called downy mildew [Figure 6] a. Grape plants infected with P. The spread of downy mildew caused the near collapse of the French wine industry in the nineteenth century. Phytophthora infestans is an oomycete responsible for potato late blight, which causes potato stalks and stems to decay into black slime [Figure 6] b.

Widespread potato blight caused by P. Late blight continues to plague potato crops in certain parts of the United States and Russia, wiping out as much as 70 percent of crops when no pesticides are applied. They are equally important on the other end of food webs as decomposers. Protists are essential sources of nutrition for many other organisms. In some cases, as in plankton, protists are consumed directly.

Alternatively, photosynthetic protists serve as producers of nutrition for other organisms by carbon fixation. For instance, photosynthetic dinoflagellates called zooxanthellae pass on most of their energy to the coral polyps that house them [Figure 7]. In this mutually beneficial relationship, the polyps provide a protective environment and nutrients for the zooxanthellae.

The polyps secrete the calcium carbonate that builds coral reefs. Without dinoflagellate symbionts, corals lose algal pigments in a process called coral bleaching, and they eventually die.

This explains why reef-building corals do not reside in waters deeper than 20 meters: Not enough light reaches those depths for dinoflagellates to photosynthesize. Finish Editing. This quiz is incomplete! To play this quiz, please finish editing it. Delete Quiz. Question 1.

Which protist group is made up of heterotrophs? How are single-celled protists different from single-celled bacteria? How are animal-like protists similar to animals? They are multicellular. Their cells contain chloroplasts. They are unicellular. They consume other organisms.