Skip to content
Home

Amoebozoa: the amoeboid eukaryotes, slime moulds, and their biology

Amoebozoa are a diverse clade of mostly unicellular eukaryotes characterized by lobose pseudopodia, phagocytic nutrition and a close evolutionary relationship to animals and fungi.

Author: Created: Updated:

Overview

Amoebozoa are a major grouping of eukaryotic organisms that includes many familiar amoebae and the slime moulds. Members are typically single-celled or form multicellular structures transiently, and are known for their amoeboid movement produced by flowing cytoplasm and broad, lobelike or fingerlike pseudopodia. Modern molecular studies support Amoebozoa as a distinct, monophyletic clade that is closely related to the lineage containing animals and fungi.

Image gallery

10 Images
Chaos carolinense
simple.wikipedia.org · CC BY-SA 2.5

Distinctive characteristics

Most amoebozoans move and feed by extending their cytoplasm to form pseudopodia, then surround and ingest particles by phagocytosis. They commonly lack elaborate microtubule-supported appendages, such as flagella, except in a few lineages where flagellated stages appear. Reproductive and survival strategies vary: many species encyst under adverse conditions, while others (notably slime moulds) form visible fruiting bodies that release spores. Cellular organization ranges from single amoeboid cells to multinucleate or multicellular aggregates.

Diversity, habitats and ecology

The group contains several thousand described species and likely many more undescribed forms. Amoebozoa inhabit soils, freshwater and marine environments, and some live as symbionts or parasites of animals and other hosts. They play ecological roles as predators of bacteria and other protists, recyclers of organic matter, and sometimes as pathogens in humans and other organisms. Slime moulds, a well-known subset, are common on decaying plant material and can often be observed producing stalked fruiting bodies.

Life cycles and behavior

Feeding cells typically take up food by engulfing particles into food vacuoles where digestion occurs. When nutrients are limited, many amoebozoans form resistant cysts that allow them to survive harsh conditions and disperse. In social slime moulds, solitary amoeboid cells can aggregate into a multicellular procession and differentiate into spores and stalk cells — a visually striking life cycle that has made these organisms useful in studies of development and cell signalling.

Phylogeny and scientific importance

Sequence-based phylogenies place Amoebozoa as a sister clade to the Opisthokonta (animals, fungi and related protists) within higher-level groupings sometimes called Unikonta, Amorphea or Opimoda. Because they occupy a branching point near the origin of major eukaryotic lineages, amoebozoans are important in research on cell motility, phagocytosis, multicellularity and the evolution of eukaryotes. The social amoeba Dictyostelium discoideum is a widely used model organism in cell and developmental biology, and certain Entamoeba species are medically important parasites.

Notable examples and distinctions

  • Amoebae: Classic lobose amoebae exemplify the typical single-celled, crawling life form.
  • Slime moulds (mycetozoans): Can be multinucleate or form multicellular aggregates and produce visible fruiting bodies.
  • Parasitic forms: Some genera include species that infect animals and humans; others live as harmless commensals.
  • Model species: Dictyostelium discoideum is used to study cell signalling, chemotaxis and development.

Further reading and key terms

Below are brief pointers to common terms and concepts associated with Amoebozoa. These links are placeholders for further definitions or sources.

Questions and answers

Q: What is Amoebozoa?

A: Amoebozoa is a eukaryote phylum of amoeba-like protozoa. It is a sister clade to the fungi and animals, and contains about 2,400 described species of amoeboid protists.

Q: How do Amoebozoa move?

A: Most Amoebozoa move by internal cytoplasmic flow, using their finger-like pseudopodia as characteristic features.

Q: What classification scheme does Amoebozoa belong to?

A: In most classification schemes, Amoebozoa is ranked as a phylum in either the kingdom Protista or the kingdom Protozoa. In the classification of the International Society of Protistologists, it is kept as an unranked "supergroup" in the Eukaryota.

Q: What are some common examples of organisms found within this group?

A: Examples of organisms found within this group include Chaos, Entamoeba, Pelomyxa and the genus Amoeba itself. Most are unicellular and can be found in soils and aquatic habitats. Some are symbionts of other organisms including several pathogens. The mycetozoans slime moulds are also included in this group which can usually be seen with the naked eye due to their multinucleate or multicellular forms that produce spores.

Q: How do these organisms feed?

A: Nutrition for these organisms occurs through phagocytosis where they cell surrounds food particles sealing them into vacuoles where they are digested and absorbed from there. When food becomes scarce many species form cysts which may be carried by air to other places; in slime moulds these structures are called spores and form on stalked structures called fruiting bodies or sporangia.

Q: Do any members have flagella?

A: Most members lack flagella but some archamoebae have flagella while many slime moulds produce biflagellate gametes; one example being Dictyostelium discoideum which is a model organism for studying this group further.

Related articles

Author

AlegsaOnline.com Amoebozoa: the amoeboid eukaryotes, slime moulds, and their biology

URL: https://en.alegsaonline.com/art/3612

Share

Sources