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Amoeboid Protozoans

Single-celled organisms that move and feed using extensions called pseudopodia. They lack cilia, pellicles, and have a single type of nucleus.

Pseudopodia

Extensions of the cell used for movement and feeding, including lobopodia, filopodia, and reticulopodia.

Lobopodia

Broad, blunt extensions of the cell used for movement and engulfing food.

Filopodia

Thin, slender projections that can branch but do not fuse to form networks.

Reticulopodia

Fine, branching pseudopodia that fuse to form complex networks, typical in foraminiferans.

Sarcodina

An outdated classification that grouped amoeboid protozoans together; now known to be polyphyletic.

Pellicle

A supportive layer beneath the cell membrane in some protozoans; absent in amoeboid protozoans.

Contractile Vacuole

A cellular structure that expels excess water from the cell; present in many freshwater amoeboid species.

Test

A protective shell or covering produced by some amoebae, composed of organic materials, calcium carbonate, or cemented particles.

Gymnamoebae

Amoeboid protozoans without external coverings, moving and feeding through various pseudopodia forms.

Arcellinida

A group of test-bearing amoebae within the Amoebozoa, characterized by lobopodia and distinct test structures.

Slime Molds (Eumycetozoa)

Organisms exhibiting both amoeboid and fungus-like characteristics during their life cycle.

Plasmodium

A large, multinucleate, single-celled mass formed by acellular slime molds.

Pseudoplasmodium

An aggregate of individual amoeboid cells forming a multicellular structure in cellular slime molds.

Sporangia

Spore-producing structures developed by slime molds under unfavorable conditions.

Mastigamoebae

Protozoans possessing both flagella and pseudopodia, indicative of a link between flagellate and amoeboid forms.

Rhizaria

A supergroup of protists characterized by slender, often complex pseudopodia, including foraminiferans and radiolarians.

Foraminifera

Marine protozoans that produce multichambered calcium carbonate tests and use reticulopodia for feeding and movement.

Phagocytosis

The process by which a cell engulfs solid particles to form an internal food vacuole.

Pinocytosis

The process of ingesting liquid and dissolved substances through small vesicles formed by the cell membrane.

Syncytium

A large cell-like structure containing multiple nuclei, formed by the fusion of cells or repeated nuclear divisions without cytokinesis.

Microtubules

Components of the cytoskeleton that support and shape the cell and aid in intracellular transport; support filopodia in some rhizarians.

Calcium Carbonate

A chemical compound used by foraminiferans to construct their tests; contributes significantly to marine sediments and geological formations.

Benthic

Refers to organisms living on or in the seabed, the bottom of a water body.

Planktonic

Refers to organisms that drift or float in the water column, unable to swim against currents.

Ectocommensal

A relationship where one organism lives on the surface of another, deriving benefit without harming the host.

Amoebozoans

This group includes naked amoebae (Gymnamoebae), which lack external coverings and use various forms of pseudopodia for movement and feeding. They are predominantly free-living and inhabit moist environments.

Arcellinids and Related Test-Bearing Amoebae

These amoebae produce protective tests (shells) composed of organic materials or cemented particles. They are common in soils and freshwater habitats and have a rich fossil record.

Slime Molds (Eumycetozoa

Slime molds exhibit both amoeboid and fungus-like characteristics during their life cycle. They can exist as individual amoeboid cells or aggregate into multicellular structures (plasmodia or pseudoplasmodia) under certain conditions, leading to the formation of sporangia that release spores.

Mastigamoebae

These organisms possess both flagella and pseudopodia, illustrating a transitional form between flagellates and amoebae. They are commonly found in stagnant aquatic environments.

Rhizaria

This group encompasses organisms with slender, often branching pseudopodia called filopodia. Notably, it includes foraminiferans and radiolarians.

Foraminifera

Primarily marine organisms that produce multichambered calcium carbonate tests with openings through which reticulopodia extend. They play a significant role in marine ecosystems and have an extensive fossil record useful in geological studies.