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South American soil leeches (Erpobdellidae) stay in moist soil, cow dung and rotten wood and act as predators of worms and insects. Terrestrial leeches commonly reside in moist vege­tation of the tropics and feed on the blood of Vertebrates.

Piscicola geometra is a brackish water sort and stays attached to base- dwelling fishes. Branchellion is identified attached to skates and rays. Echiurids are semisessile and marine ani­mals many types stay in burrows, and cavi­ties made by other animals or on empty shells of molluscs.

Annelids change extensively regarding their sizes. Most polychaetes are minute to moderate in dimensions but Neanthes brandti of Californian coastline attains a sizing of about 1. Oligochaetes like Chaetogaster, Aeolosoma are a couple cm in duration but a few attain huge dimension. Rhinodrilus fafneri of Ecuador and Australian Megascolides australis improve over two metres in duration and 25 mm in diameter.

The average size of leeches is concerning 10 and two hundred mm. 4. Generalised Characters of Phylum Annelida:The annelida as the identify indicates (annulus = ring) are segmented worms and the segments in a lot of situations are externally recog­nised as ring-like constrictions.

In many types a distinctive head consisting of a pre-oral ‘prostomium’ and a post-oral ‘peristomium’ is existing. In most of the kinds anterior, posterior, dorsal and ventral surfaces are effectively-recognised. The foodstuff canal is a straight tube with demarked regions and extends from anterior mouth to terminal anus.

In numerous forms the perivisceral cavity or coe­lom is properly-produced. The coelom is lined with mesoderm and communicates to the exterior via paired nephridia. The entire body wall is muscular having round and longi­tudinal layers of muscle tissues and lots of have setae embedded in skin.

Common users have slender and non-chitinous cuticle. The blood-vascular method is of closed sort. The organs of excretion are metamerically ar­ranged tubular nephridia or tegmental or­gans which are shut internally or direct from coelom to exterior.

A collection of paired ducts known as coelomoducts, possibly united with or distinct from the nephridia might be current to have the reproductive components outside the house. The central nervous program is composed of a pair of pre-oral ganglia connected by commissure with a pair of ventral cords which is ex­panded at each section to form ganglion. Growth might be immediate or oblique. The larva is referred to as trochophore and undergoes metamorphosis. 5. Specialised Figures of Phylum Annelida:In Annelids the triploblastic problem has attained perfection.

The human body cavity is a real coelom which lies among the overall body wall and the tubular foods canal. The overall body approach could be very best described as a tube in just a tube. This structural plan is managed in greater types. Definite segmentation is encountered in annelids. The physique is composed of various distinctive segments organized in a linear collection.

Bilateral symmetry is well represented in annelida and this is an evolutionary advance­ment around more primitive radial symmetry. Anxious method of annelids is much more organ­ised and is composed of a pair of dorsally-positioned cerebral ganglia and ventral nerve cord. The nerve cells are dispersed in the nerve cord and ganglia. The tendency of ‘Head’ forma­tion is unique. Head is commonly connected with feeling organs and as the perception organs support the animal to maintain in touch with the sur­roundings, they are usually housed at that close of the physique which stays directed forward all through locomotion.

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