Minor Phyla
| These are group of multicellular invertebrates which are less common, and have unclear phylogenetic position. Many of these have characteristics similar to specific major phyla but at the same time they have significant differences from that phyla due to which they can not be placed under one phyla.some zoologists have placed such phyla as sub division or class under major phyla..so in simple terms we can say that minor phyla are small phyla which have small number of species,mostly small number of individuals and there phylogenetic position is not fully clear./ |
| They have both advanced and primitive features.some advanced features of minor phyla are .1.presence of contractile heart in brachiopoda.this is an advancement over contractile blood vessels.2.in chaetognatha the epidermis is multilayered .this is perhaps the beginning of formation of stratified epithelium found in vertebrates.3.post anal tail in chaetognatha is a character similar to chordata. |
| categories of minor phyla/there are three categories of minor phyla |
| 1.minor acoelomates : in these phyla coelom is absent.the space between digestive tract and body wall is filled with parenchyma or mesenchyme .these are : phylum mesozoa,phylum ctenophora,phylum nemertinea (rhynchocephalia). 2.minor pseudocoelomates : they have pseudocoelom which is lined on outside by mesoderm and on inner side by endoderm.these are : phylum entoprocta,phylum ancanthocephala,phylum nematomorpha,phylum rotifera,phylum gastrotricha,phylum kinorhyncha,phylum nematoda 3.minor coelomates : they have coelom which is bounded throughout by mesoderm.these include : phylum ectoprocta (bryozoa),phylum phoronida,phylum priapulida,phylum echiurodea,phylum brachiata,phylum sipunculida, phylum chaetognatha,phylum brachiopoda. | ||
| An article by: Vigyan Tutorials.Biology Coaching Classes by Ashwani kumar,,Biology teacher NewPatel Nagar opp Anoop hospital Phagwara | ||
