Like the other multicellular kingdoms most scientists now believe that it is the Colonial theory by which the animals (metazoans) evolved. The most likely group of protists that we evolved from is the Choanoflagellates and there has been movements to put them in the Animal Kingdom for this reason. Proterospongia Haeckli is a rare type of choanoflagellate which shows primitive differentiation. They are remarkably similar to Sponges although they have no alimentary canals like sponges do (Proterospongia Haeckli move themselves through the water) and have slightly more than two types of differentiated cell than the Proterospongia Haeckli. Apart from these differences they are very similar and although the Proterospongia Haeckli aren't the ancestors of sponges (the most basic animals as they only work on a cellular level) they show what the first multicellular organisms could of been like. In politics, a country (or in some cases, a group of countries) over which a king or queen reigns, is a kingdom, see: monarchy. ... Typical phyla Rhodophyta (red algae) Chromista Heterokontophyta (heterokonts) Haptophyta Cryptophyta (cryptomonads) Alveolates Pyrrhophyta (dinoflagellates) Apicomplexa Ciliophora (ciliates) Excavates Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Amoebozoa Choanozoa Many others; classification varies The Kingdom Protista or Protoctista is one of the commonly recognized biological kingdoms, including all the eukaryotes except for... The choanoflagellates are a group of flagellate protozoa. ... See Animal. ... This article is about the animal. ...

Molecular evidence also shows Choanoflagellates and Animals (and also fungi) being closely linked. using phylogenetics using rRNA (as has been highly conserved and presnt in pretty much all organisms) as the source of the DNA to compare discrepencies and similarities of several thousand base pairs, to see how closely related the animals and the proterospongia are, and to see if they are homologous with each other. However, what appears as two similar genes could well turn out to of branched from completely different ancestors and instead could of turned out to be convergent evolution. Therefore, more genes need to be compared to make sure of the ancestery of animals. The choanoflagellates are a group of flagellate protozoa. ... Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... A non-coding RNA (ncRNA) is any RNA molecule that functions without being translated into a protein. ... Two or more structures are said to be homologous if they are alike because of shared ancestry. ... In evolutionary biology, convergent evolution describes the process whereby organisms not closely related independently acquire similar characteristics while evolving in separate and sometimes varying ecosystems. ...

Sponges

Some of the earliest animals were Sponges. There are many thousand species, are filter feeders, mostly marine and sessile. they are very basic as they have no nervous system, circulatory system or body cavity (acoelamate). They also have no organs or tissue and operate at the cellular level meaning each cell, although cooperating, still acts relatively independantly. This is why you can put a sponge in a blender and the cells will converge again forming a new organism. They are actually more like colonial flagellates than an actual multicellular organism. Like the proterospongia they use beating collar cells (very similar to choanoflagellates) to create a water current through the spongecoel (alimentary canals inside the sponge) where they feed via intracellular digestion (they have no digestive cavity). Although the sponges seem very primitive with many claiming they are dead end of evolution. It is actually much more likely that they simply don't need to evolve any more adaptions. For the niche it occupies any more adaptions would not really aid the sponge at all. For instance how would eyes, a nervous system etc or any other kind of adaption help the sponge filter feed? This article is about the animal. ... This article is about the animal. ... Filter feeders (also known as suspension feeders) are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized structure, such as the baleen of baleen whales. ... This page is a candidate to be moved to Wiktionary. ... The nervous system of an animal coordinates the activity of the muscles, monitors the organs, constructs and processes input from the senses, and initiates actions. ... The main organs of the circulatory system is the heart, the blood, and the blood vessels. ... An organ is the following: In anatomy, an organ is a group of tissues which perform some function. ... Look up Tissue on Wiktionary, the free dictionary The word tissue has several meanings: Aerial tissu is an acrobatic art form, and is one of the circus arts. ...