Zoology

  CHAETOPTERUS CLASSIFICATION : Phylum : Annelida Class : Polychaeta Genus : Chaetopterus COMMENTS : •Commonly a Paddle worm. •It is usually 15 cm to 35 cm in length. •The body is divisible into three distinct regions - anterior , posterior & middle . •The anterior region is flat, and usually has nine pairs of simple parapodia which are expanded notopodia, samall prostonium and a funnel shaped peristomial collar with a pair of peristomial cirri & mouth .  •Middle region comprises five segments , first anterior most is produced laterally into great wings directed forwards, next segment carries a pair of suckers & the rest there are segments carry membranous folds so called fans formed by the fusion of the notopodia . •Posterior region comprises thirty similar segments which are devoid of setae •Mouth is wide & funnel-shaped . •The food comprises mainly small organisms which are carried by the currents of water set up by fans. It is a the filter feeder . •Highly p

SERPULA CLASSIFICATION : Phylum : Annelida Class : Polychaeta Genus : Serpula COMMENTS : •Body of Serpula is elongated, cylindrical & vermiform, measuring 3.5 cm to 4cm in length. •Elongated body has a head, thorax & abdomen. •The anterior end forms the head consisting of prostomium & peristomium . •Prostomium is provided with a pair of semi-circular feathered gills which are modified palps. •Peristomium is produced into a collar which folds backwards . •Thoracic membrane present on each side is formed by fusion of the dorsal and ventral cirri of the thoracic segments . • Operculum is formed by the terminal enlargement of one of the dorsal gills fillaments. Operculum serves to close the opening of the tube. •The gills are modified palps, sometimes supported by cartilagenous segments and are richly supplied with blood. •Each gills consists of an elongated branch having two rows of short filaments . • Gills serve as respiratory & food collecting organs.

  Hirudineria   CLASSIFICATION : Phylum : Annelida Class : Hirudinea Genus : Hirudineria COMMENTS : •Commonly known as leech . •Body is elongated , dorso-ventrally flattened , measuring 30-35cm in length with dorsal surface green & ventral surface orange yellow in colour. •Body is divided metamerically into 38 somites or segments. Each segment is divided into rings or annuli . •Anterior & posterior suckers are well developed . •Anterior sucker is oval & ventral bearing triradiate shape of mouth. •Posterior sucker is circular & forms a highly muscular disc at the posterior end as a powerful organ of adhesion & locomotion . •Dorsal fine segments bears five pairs of eyes . •Alimentary canal is straight tube, mid-dorsal , placed on 25th segment . • Nephridia are seventeen pairs segmentally arranged from 6-22 segments opening by nephridiopores  on the ventral suface. •They are Hermaphrodite .   Male organs of testis sac , vasa efferentia , vas deferens , epi

PHERETIMA CLASSIFICATION : Phylum : Annelida Class : Oligochaeta Genus : Pheretima COMMENTS : •Commonly known as Earthworm . •Body is long , narrow and cylindrical measuring upto 150 mm in lengths, brown in colour. • Anterior end is pointed , while the posterior end is more or less blunt . •Body is divided by circular furrows into a series by 120 ring-like segments or metameres . •Each segment (except the first & last) is provided with setae arranged in a ring enclosing the setal sac . •Mouth is crescentic aperture situated at the anterior end ventral to the prostomium . • Clitellum , a circulal band of glandular tissue, is present in 14th to 16th segment . •They are Hermaphrodite. But they do cross fertilization , no case of self fertilization is reported yet. • Female genital pore lies on the ventral surface in the 14th segment . •A pair of male genital pore is situated ventrally in the 18th segment. •Two pairs of genital papillae lie on the ventral surface in the

  SABELLA CLASSIFICATION : Phylum : Annelida Class : Polychaeta Genus : Sabella COMMENTS : • Sabella is commonly called Peacock worm . •Body is elongated, vermiform,metamerically segmented, measuring 24 to 28 cm in length. •Body comprises small head , thorax & abdomen . •Head consists of prostomium bearing tentacles, peristomium & collar region with segments. •Each tentacle bears two rows of small pinnules (hipinnate) having mucus- secreting. •Thorax consists of eight segments bearing parapodia having dorsal lobe hair like, ventral lobe hooked. •Abdomen consists of about 300 segments bearing parapodia having hooked dorsal- lobe & hair - like ventral lobe. •A dorsal faecal groove extends from mouth to anus. • Sabella is filter feeder , feeding by the movement of tentacles.

  Heteronereis CLASSIFICATION Phylum : Annelida Class : Polychaeta Genus : Heteronereis COMMENTS : • Heteronereis is the sexual form  of Nereis . •Some species of Nereis exhibit dimorphism and two distinct phases, Nereis phase & Heteronereis phase , occur in their life. •In such forms, the sexual maturity accompanied by certain changes in structure . •Heteronereis phase is the sexual phase exhibits the following characteristic features: • Eyes become large & much more prominent, and highly sensitive to light. •The body shows two distinct regions, an anterior atoke or non- sexual region and a posterior modified epitoke or sexual region which contains ova & sperms . • Parapodia in the posterior sexual region of the body become enlarged , vascular & foliaceous and setae become oar - shaped which help in active swimming. •Dorsal & ventral cirri of the parapodia appears to be highly enlarged . •The notopodium & neuropodium become large & leaf-like &a

  APHRODITE CLASSIFICATION : Phylum : Annelida Class : Polychaeta Genus : Aphrodite COMMENTS : • Aphrodite is commonly known as sea mouse. •It measures about 7.5 to 12.5cm in length and made up of 30-35 segments . •Body is short & broad, oval in shape & dorso- ventrally flattened. •Thick long setae of the notopodium are irridescent , they are woven into a blanket which covers the dorsal surface (back) including the elytra . •Ventral surface is flat, segmented & forms a creeping sole . •Between blanket and dorsal body wall is a space containing 15 pairs of elytra formed from modified dorsal cirri . •Stiff setae & irridescent bristles are also present on dorsal surface. •Head is small, situated anteriorly beneath the dorsal felt and bears a single small median tentacle & two large lateral palps. • Coelomic epithelium is ciliated which causes circulation, and projecting into rectum a series of strongly  cliated ridges.

NEREIS CLASSIFICATION : Phylum : Annelida class  : Polychaeta Genus :  Nereis COMMENTS : • Nereis  is commonly called  rag worm  or  clam worm . •The body is long, slender & dorso-ventrally flattered reaching a  length of 5-30 cm. •The body consists of distinct head followed by a no. similar segments. •Head consists of two parts: a roughly triangular anterior lobe, the  prostomium  and a posterior ring like portion, the  peristomium . •Prostomium bears a  pair of terminal tentacles , dorsally two pairs of eyes & ventrally a pair of jointed  palps . •Peristomium bears four slender cylindrical tentacles on each side & a  transverse aperture , the  mouth on the ventral surface . •Each segment of the body behind peristomium bears a pair of appendages known as  anal cirri  and  terminal anus . •At the bases of parapodia on the ventral side in each segment are the paired openings of the nephridia, the  nephridiopores . •Sexes are separate,  gonads develop temporarily  during repr

PHYLUM ANNELIDA GENERAL CHARACTERISTICS : •Annelids are mostly aquatic, Marine or freshwater,  burrowing or lining in tubes, some free living forms. •Body triploblastic, symmetrical, elongated & vermiform. •The body is metamerically segmented , externally by transverse grooves & internally by septa into a number of divisions, each division is called segment by metamere or somite . •First segment is called peristomium which contains a part having mouth. This part is called prostomium . Last segment contains a part having anus called pygidium . •The body wall consists of moist cuticle , it is single layered epidermis of columnar cells and well developed musculature , the cuticle is a lbuminoid . •Body wall contractile , consists of an outer epidermis, Circular & longitudinal muscles . •Appendages when present are unjointed . •Locomotory organs are segmentally arranged, paired sitae or chaitae . •Presence of three coelom divided by intersegmental septa . •Alimentary ca