Pseudopodia
A pseudopodium or pseudopod (plural: pseudopodia or pseudopods) is a temporary cytoplasmic extension of an amoeboid cell, used for locomotion and for capturing and ingesting food. The term literally means “false foot”. Pseudopodia are powered by microfilaments located near the cell membrane; in many amoebae, microfilaments occupy roughly half of the internal cell volume.
A pseudopodium contains both granuloplasm and hyaloplasm. Pseudopodia composed only of hyaloplasm are called subpseudopodia.
Amoeba proteus, arrows indicate four of the numerous pseudopodia.
The form and structure of pseudopodia are important taxonomic characters. Based on their shape, several types are distinguished:
Lobopodia — more or less finger‑like pseudopodia; the most common type. Lobose amoebae form by far the largest group. Subpseudopodia often arise from lobopodia.
Filopodia — thin, slender, thread‑like pseudopodia. They may branch or anastomose, depending on the taxon. Filopodia are typical of many Rhizaria.
Reticulopodia — pseudopodia that anastomose (i.e., make contact and fuse), forming a network (reticulum). They may or may not contain granules.
Granulopodia — filopodia with a granular structure. The granules, called extrusomes, play a role in prey capture. Granulopodia may branch and sometimes anastomose.
Granuloreticulopodia — granulated, branching, anastomosing filopodia forming complex pseudopodial networks, with rapid bidirectional streaming of granules (as in Foraminifera) or two‑way streaming (e.g., Trivalvularidae).
Axopodia — stiff filopodia supported by regular arrays of microtubules. Amoeboids with axopodia include Radiolaria and Heliozoa.
Lamellipodia — broad, very thin, veil‑like pseudopodia. Many amoebae use a combination of filopodia and lamellipodia during movement.