In this classification no Linnaean categories of above family this kind of as superfamily, get, and subclass are utilized. Again, Westheide (1997) divided Polychaeta into 25 orders which consist of all the described species.
Pechenik (2000) categorized Annelida into four courses:rn(iii) Pogonophora and. He contains oligochaetes (Oligochaeta) and leeches (Hirudinea) under the class Clitellata and destinations all the species into two subclasses:rn(i) Oligochaeta (earthworms) and.
rn(ii) Hirudinea (leeches). Brusca and Brusca (2003) claimed that the recent phylogenetic reasearch indicates the unification of two classes, Oligochaeta and Hirudinea into a one class Clitellata. The scheme of classification has adopted in this reserve ( ) from “Invertebrate Zoology” penned by Ruppert and Barnes (1994). Classification with Characters:Class one.
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Polychaeta (Gk. poly – a lot of chaeta = setae):1.
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Overall body elongated, segmented with identical, cylindrical overall body segments. 2. Anterior conclusion modified into a head.
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3. A distrinct head bears sensory appendages, these as eyes, antennae, cirri and palps. 4. Several setae on the trunk segments, therefore identified as polychaeta.
5. Each and every human body phase bears a pair of fleshy, lateral, paddle-like outgrowths, named parapodia, bearing numerous prolonged setae in setigerous sacs.
The parapodia act as locomotory and respiratory organs. 6. Parapodia in essence biramous and supported by acicula. 7.
Clitellum absent. 8. Alimentary canal is provided with an eversible buccal location and protrusible pharynx. 9. Really vascularised gills are current in most big-sized polychaetes utilised for gas exchange. 10. Brain advanced is exact than oligochaeta and divided into three areas:rn(ii) Mid-mind https://www.reddit.com/r/PaperHub/comments/x9r6o1/paper_help/ and. 11.
Protonephridia existing in a number of families. Segmental metanephridial methods in most instances. 12.
Sexes individual (gonochoristic) in most. 13. Epitoky, a reproductive phenomenon viewed in some polychaetes (e. g. , nereids, syllids and eunicids). 14. Fertilization exterior. 15. A trochophore larval phase in the life cycle. 16. Completely marine, and mainly carnivorous but some are herbivorous. Scheme of Classification:Distribution:Fauvel (1953) described that numerous of the polychaetes are truly cosmopolitan and most of the species are widespread in the Indo-Pacific coasts. Many species have a around the globe distribution and the inter-tropical are the same in all the oceans. Hence the distribution of polychaeta is largely limited by temperature. Trend in polychaete classification:The class polychaeta is not divided into subclasses or orders. Some authors, these as Knox (1972) divided into subclass rank:rn(i) Subclass Errantia and. rn(ii) Subclass Sedentaria. But this subdivision is an artificial, not a purely natural a single. So most of the researchers divide polychaeta into two groups. rn(A) Group I. Polychaeta errantia (Wandering polychaetes) [L. mantis = wandering]:rn(i) Numerous and ordinarily related segments.