Heliozoa, or sun animalcules, are roughly spherical amoeboids with many stiff, microtubule-supported projections called axopods radiating outward from the cell surface. These give them the characteristic sun-like appearance for which they are named, and are variously used for capturing food, sensation, movement, and attachment. They are similar to radiolaria, but they are distinguished from them by lacking central capsules and other complex skeletal elements, although some produce simple scales and spines. They may be found in both fresh water and marine environments.

Originally the heliozoa were treated together as a formal class Heliozoa or Heliozoea, but the various orders show notable differences and are no longer believed to be related. Instead, heliozoa is regarded as a descriptive term applying to various lines of protists. These include the following:

* Actinophryids and some other axodines
* Centrohelids
* Desmothoracids
* Dimorphids
* Gymnosphaerids
* "Sticholonche"

Several nucleariids were once considered heliozoa, but they do not have microtubule-supported axopods and so are now considered filose amoeboids instead.

Actinosphaerium (single-celled) is an example of a heliozoa. For an image seehttp://www.microscopy-uk.org.uk/index.html?http://www.microscopy-uk.org.uk/ponddip/

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  • Heliozoa — He li*o*zo a, n. pl. [NL., fr. Gr. ? the sun + zo^,on an animal.] (Zo[ o]l.) An order of fresh water rhizopods having a more or less globular form, with slender radiating pseudopodia; the sun animalcule …   The Collaborative International Dictionary of English

  • Heliozoa — Heliozōa, s. Sonnentierchen …   Kleines Konversations-Lexikon

  • Heliozoa —   [griechisch zõon »Lebewesen«], Heliozoen, die Sonnentierchen.   …   Universal-Lexikon

  • Heliozoa — Heliozoa, Sonnentierchen, v. a. süßwasserbewohnende Arten umfassende Klasse der ⇒ Rhizopoda; äußerlich den ⇒ Radiolaria ähnlich, jedoch ohne Zentralkapsel …   Deutsch wörterbuch der biologie

  • Heliozoa — Für die systematische Einteilung der Lebewesen existieren nebeneinander mehrere Vorschläge. Das hier behandelte Taxon entspricht nicht der gegenwärtig in der deutschsprachigen Wikipedia verwendeten Systematik. Acanthocystis turfacea, ein… …   Deutsch Wikipedia

  • Heliozoa — Sección de un axopodio mostrando los microtúbulos. Los Heliozoa (helios = sol; zoo = animal) son ameboides de forma aproximadamente esférica con numerosas proyecciones soportadas por microtúbulos llamadas axopodios que irradian hacia fuera desde… …   Wikipedia Español

  • Heliozoa — Héliozoaires Actinophrys …   Wikipédia en Français

  • Heliozoa — noun mostly freshwater protozoa • Syn: ↑order Heliozoa • Hypernyms: ↑animal order • Member Holonyms: ↑Actinopoda, ↑subclass Actinopoda • Member Meronyms: ↑ …   Useful english dictionary

  • Heliozoa — Amoeboid Protozoa, Order Heliozoida. They are generally free floating, spherical cells with many straight, slender microtubule supported pseudopods radiating from the cell body like a sunburst. These modified pseudopods are termed axopodia.… …   Dictionary of molecular biology

  • heliozoa — he·lio·zoa …   English syllables