Phylum Annelida. (segmented worms, bristle worms). 15, species large successful phylum in water & on land include earthworms, sand worms, bristle. Phylum Annelida. Segmented Worms. Characteristics. - Segmentation. - Chaetae (Hairs made of Chitin. - 3 Cell Layers. - True Coelom. - Head develops first. Annelida. Arthropoda. Bryozoa. Phoronida. Brachiopoda. Echinodermata. Chordata phyla. Pseudocoelomates. Coelomates. A Phylogeny of the Animal Phyla.
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Phylum Annelida In: Atkinson LJ and Sink KJ (eds). Field Guide to the Ofshore Marine Invertebrates of South Africa,. Malachite Marketing and Media, Pretoria, pp. PHYLUM Annelida. CLASS Polychaeta. A. Note parapodium w/ setae & acicula ( A). Parapodia are used for locomotion, sensory purposes & respiration. [fig. Oligochaeta - “few chaetae” a subclass of Clitellata. • many terrestrial and freshwater but few marine species. – mostly thread-sized. – mostly deposit- feeders.
Oligochaetes, including earthworms, burrow into soil; certain small oligochaetes are found in fresh water, and a few are marine, usually inhabiting estuarial or other shallow waters. Leeches, which number about species, inhabit freshwater or humid environments and are carnivorous or parasitic on other organisms—e.
Size range and diversity of structure The length of annelids varies from a fraction of an inch to more than six metres about 20 feet.
The width may exceed 2. Free-moving polychaetes and earthworms include the largest species.
Leeches attain lengths of about 0. Polychaetes The body of free-moving polychaetes see figure consists of a head, or prostomium, which may bear two or more eyes; a preoral segment, with such appendages as antennae, tentacles, and palpi fleshy sensory projections ; a trunk divisible into distinct segments; and a tail, or pygidium, which may bear anal cirri fleshy projections or plaques and a terminal anus. Each body segment following the second segment peristome usually has paired parapodia; i.
The parapodia, generally prominent in free-moving polychaetes, bear bundles of setae, which can be extended, and aciculae needlelike structures , which are used for support. Facts Matter. Start Your Free Trial Today The heads of sedentary polychaetes see figure may be distinct or indistinct. Forms with a distinct head generally lack head appendages. Branchiae, or gills , which serve for respiration and as food-gathering organs, are well-developed in many of the tube-dwelling forms.
Some have tentacles at the anterior front end, and gills arise from the dorsal upper surface of a few anterior segments. In these species food is gathered by the tentacles and respiration is confined to the gills.
Phylum Annelida Circulatory & Nervous Systems
The rest of the body is divided into thoracic and abdominal regions. Parapodia, if present, are generally simple lobes; frequently the setae project directly from the body wall.
It appears to have bristles on its head segment akin to those along its body, as if the head simply developed as a specialized version of a previously generic segment. Sipuncula , previously a separate phylum. Hirudinea leeches. Aeolosomatidae . Echiura , previously a separate phylum. Siboglinidae , previously phylum Pogonophora. Traditionally the annelids have been divided into two major groups, the polychaetes and clitellates. In turn the clitellates were divided into oligochaetes , which include earthworms , and hirudinomorphs , whose best-known members are leeches.
Also in Damhnait McHugh, using molecular phylogenetics to compare similarities and differences in one gene, presented a very different view, in which: In Torsten Struck and colleagues compared 3 genes in 81 taxa , of which 9 were outgroups,  in other words not considered closely related to annelids but included to give an indication of where the organisms under study are placed on the larger tree of life.
This analysis agreed that clitellates, pogonophorans and echiurans were on various branches of the polychaete family tree. It also concluded that the classification of polychaetes into Scolecida, Canalipalpata and Aciculata was useless, as the members of these alleged groups were scattered all over the family tree derived from comparing the 81 taxa. In addition, it also placed sipunculans , generally regarded at the time as a separate phylum, on another branch of the polychaete tree, and concluded that leeches were a sub-group of oligochaetes rather than their sister-group among the clitellates.
In addition to re-writing the classification of annelids and 3 previously independent phyla, the molecular phylogenetics analyses undermine the emphasis that decades of previous writings placed on the importance of segmentation in the classification of invertebrates.
Polychaetes, which these analyses found to be the parent group, have completely segmented bodies, while polychaetes' echiurans and sipunculan offshoots are not segmented and pogonophores are segmented only in the rear parts of their bodies.
It now seems that segmentation can appear and disappear much more easily in the course of evolution than was previously thought.
Acoelomorpha Acoela and Nemertodermatida. Deuterostomia Echinoderms , chordates , etc. Ecdysozoa Arthropods , nematodes , priapulids , etc. Phoronida and Brachiopoda. Annelids are members of the protostomes , one of the two major superphyla of bilaterian animals — the other is the deuterostomes , which includes vertebrates.
However, the genes that drive segmentation in arthropods do not appear to do the same in annelids.
Earthworms, Leeches, and Polychaetes - Oh My!
Arthropods and annelids both have close relatives that are unsegmented. It is at least as easy to assume that they evolved segmented bodies independently as it is to assume that the ancestral protostome or bilaterian was segmented and that segmentation disappeared in many descendant phyla. The "Lophotrochozoa" hypothesis is also supported by the fact that many phyla within this group, including annelids, molluscs , nemerteans and flatworms , follow a similar pattern in the fertilized egg's development.
When their cells divide after the 4-cell stage, descendants of these 4 cells form a spiral pattern. In these phyla the "fates" of the embryo's cells, in other words the roles their descendants will play in the adult animal, are the same and can be predicted from a very early stage.
From Wikipedia, the free encyclopedia. Phylum of segmented worms. Temporal range: O Mouth. Growth zone. O Anus. Play media. Apical tuft cilia. Prototroch cilia. Metatroch cilia. See also: List of Annelid families. Struck, T. May Biological Reviews of the Cambridge Philosophical Society.
In Baynes, T. New York: Charles Scribner's Sons. In Chisholm, Hugh. Cambridge University Press. Encyclopedia of Life Sciences. Cosmopolitan Earthworms. VermEcology, Yokohama. Invertebrate Zoology 7 ed. July Biology International.
Retrieved BMC Evolutionary Biology. Reproductive Biology and Phylogeny of Annelida". Integrative and Comparative Biology. In Anderson, D. Invertebrate Zoology. Oxford University Press. Molecular Biology and Evolution. BMC Genomics. Communicative and Integrative Biology.
August Cellular and Molecular Life Sciences. June September Zoologica Scripta. Archived PDF from the original on 20 March Some contributions of the new microscopy to the new animal phylogeny". Animal Diversity 4th ed. Mc Graw Hill. Invertebrate Zoology 7th ed. In Cracraft, J.
Assembling the tree of life. Oxford University Press US. Invertebrate conservation and agricultural ecosystems.
The worm book. Ten Speed Press. Biology and ecology of arthworms. February Practical Fresh Water Fishing. Read Books. The Economist. Acta Palaeontologica Polonica.
Archived PDF from the original on 27 March Estonian Journal of Earth Sciences.
Phylum Annelida: Habitat, Features and Classification
In Roach, I. Advances in Regolith. Australian Journal of Earth Sciences. Canadian Journal of Earth Sciences. Segmented worms: The Tree of Life Web Project. Tree of Life Project. Archived from the original on 12 April Annual Review of Ecology, Evolution, and Systematics.
A quick review". University of California Museum of Paleontology. Archived from the original on 15 April Turbeville; L. Linford; M.
Rivera; J. Garey; R. Raff; J. Lake April What have we learned from annelids? In Hall, B. Environment, Development, and Evolution.
MIT Press. Extant Animal phyla. Porifera sponges. Ctenophora comb jellies. Placozoa Trichoplax Cnidaria jellyfish and relatives. Xenacoelomorpha Xenoturbellida Xenoturbella Acoelomorpha acoels nemertodermatids.
Echinodermata starfish and relatives Hemichordata acorn worms pterobranchs. Kinorhyncha mud dragons Priapulida penis worms. Nematoda roundworms Nematomorpha horsehair worms. Loricifera corset animals. Onychophora velvet worms. Arthropoda arthropods Tardigrada waterbears. Chaetognatha arrow worms Gnathostomulida jaw worms. Micrognathozoa Limnognathia Syndermata Rotifera wheel animals Acanthocephala thorny-headed worms.
Orthonectida Dicyemida or Rhombozoa Monoblastozoa Salinella. Platyhelminthes flatworms Gastrotricha hairybacks. Cycliophora Symbion Annelida ringed worms. Mollusca molluscs. Nemertea ribbon worms.
Entoprocta or Kamptozoa Ectoprocta moss animals. Brachiopoda lamp shells Phoronida horseshoe worms. Taxon identifiers Wikidata: Q Wikispecies: Annelida ADW: Annelida EoL: Authority control GND: Retrieved from " https: Annelids Early Ordovician first appearances Extant Ordovician first appearances. Hidden categories: Wikipedia articles incorporating a citation from EB9 Wikipedia articles incorporating a citation from the Encyclopaedia Britannica with Wikisource reference All articles with dead external links Articles with dead external links from July Articles with permanently dead external links Articles with short description Wikipedia indefinitely move-protected pages Good articles Articles with 'species' microformats Articles containing Latin-language text Wikipedia articles with GND identifiers Wikipedia articles with LCCN identifiers Wikipedia articles with NDL identifiers Articles containing video clips.
Namespaces Article Talk.Leeches generally use suckers at their front and rear ends to move like inchworms. Read Books. The Echiura has traditionally been classified into the three orders: Echiuroinea with Echiuridae, Thalassematidae, and Bonelliidae , Xenopneusta Urechidae , and Heteromyota with Ikedidae .
The phylum includes earthworms, polychaete worms, and leeches.
As a result, the hindmost segment before the growth zone and pygidium has no structure that extracts its wastes, as there is no following segment to filter and discharge them, while the first segment contains an extraction structure that passes wastes to the second, but does not contain the structures that re-filter and discharge urine.
Earthworms are hermaphrodites and can self-fertilize, but prefer to cross-fertilize if possible. Most annelids have chitinous hairlike extensions in every segment called chaetae that are anchored in the epidermis, although the number and size of chaetae can vary in the different classes.