Phlum annelida

A PowerPoint presentation by
SARTHAK SHEKHAR

Content
 General feature
 General characteristic
 Body structure
 Locomotion
 Features related to body
 Features related to digestive system
 Features related to respiratory system
 Features related to circulatory system
 Features related to excretory system
 Features related to nervous system
 Classification
 Special points

General Features
 What does the phylum annelida includes???
The answer is that it includes over 9000 species of
metamerically segmented animals with true coelom.
 Who coined the term annelida???
Lamarck termed the word annelida due to the
metamerically segmented rings that these organism
possess called “Annuli”

General Characteristic
 HABITATE
They are free living animals, found in the moist soil, fresh water
,sea or few are parasite.
 SYMMETRY
These organism are bilaterally symmetry.
 GERM LAYER
These organism are triploblastic in nature.
 LEVEL OF ORGANISATION
These organism have organ system grade level of organisation.
 BODY PLAN
These organism have tube within tube plan.

Body Structure
Soft and elongated
Cylindrical
Flattened
Divided into segments
Metameres by rings called ANNULI.
CEPHALISATION present
in(polychaeta)

locomotion
PARAPODIA-polychaeta
CHITINOUS SEATE-oligochaeta
MUSCULAR CONTRACTION-
hirudinea

Features Related To Body
 CUTICLE
 EPIDERMIS
 MUSCLE LAYER (Longitudinal and circular)
 First protostomic eucoelomate animals
 Body cavity is true coelom lined by MESODERMAL
coelomic epithelium.(SCHIZOCOEL)
 NO SKELETON IS PRESENT

Features Related Digestive System
 DIGESTIVE TRACT IS COMPLETE
 It is straight
 It extends throughout the body
 The gut has both longitudinal and circular muscles
 Digestive gland are developed for the first time in
annelida

Features Related respiratory
System
 Respiration mostly occur through skin
 This type of respiration is called CUTANEOUS RESPIRATION
 Some have gills for respiration present in polychaeta.
 This type of respiration is called Branchial Respiration

Features Related Circulatory
System
 Circulatory system is closed
 Some blood vessels enlarge to act as pumping heart
 Heart appeared for the first time in annelida
 Blood is red in colour but the haemoglobin is dissolved
in plasma (Erythrocruorin)
(chlorocruorin)

Features Related Excretory System
 Excretory organ is nephridia which is further of 2
types
i. ECTO-integumentary
ii. ENDO-1.septa nephridia
2.pharyngial nephiridia
 Coiled tubules which also helps in osmoregulation
 Excretory matter is of 2 types
1. Ammonia in aquatic form
2. Urea in land form

Features Related Nervous System
 Nervous system consist of following types
1. A circum pharyngeal nerve ring, these are of 3
types
A. Supra pharyngial ganglio
B. Connectives
C. Sub pharyngial
1. A double midventral nerve chord
2. Nerve chord is paired ganglia 8 connectives

Features Related Reproductive
System
 Sexes may be separate ( Dioecious, eg-Nereis )
 Or they may be united( Monoecious, eg –Earthworm)
 Reproduction is sexual
 Development is direct or indirect
 Larva is trochophore larva

Classification of Annelida
 Annelida is classified into four classes namely
 Polychaeta
 Oligochaeta
 Hirudinea
 Archiannelida

Polychaeta
 Mostly marine and free-living
 Many setae, on fleshy lateral outgrowths of the body
wall known as parapodia
 Well developed head bearing appendages,
cephalisation present
 Sexes separate, with a free-swimming trochophore
larva
 Citellum absent

Polychaeta(Contd.)
 Body is divided into three regions:
1. Atoke -asexual body region
2. Epitoke -sexual body region
3. Heteronereis-anterior-atoke,posterior-epitoke
 Ex. Nereis, Chaetopterus- paddle worm shows bio-
florescence, great power of regeneration.

Oligochaeta
 Are terrestrial with a few aquatic species or moist soil
 Have few setae no. of seate is limited
 No parapodia
 No distinct head appendages
 Clitellum present for cocoon formation
 Hermaphrodites, with copulation required
 Eggs are deposited in a cocoon and development is direct
 Ex. Pheretima and Eutphaeus ARE NORTH INDIAN
EARTH WORM
 MEGASCOLEX DRAVIDA LARGEST EARTHWORM
SOUTH INDIA

Hirudinea
 Ectoparasites, blood sucker sanguivorous
 No setae or parapodia
 Clitellum present only during reproduction(9-11
segments)
 Two suckers – anterior and posterior
 Anti coaugulant hirudin present in saliva
 Bisexual and direct development
 Number of segments 33 are fixed

Hirudinea(Contd.)
 Haemocoelomic system is present . A special type of
mesodermal tissue botrydial tissue made up of adipose
tissue for fat storage is present
 Ex. Bonellia -sea leech male is ill developed and lives
permanently in the uterus of female (unisexual)
,Hirudo-medicinal leech (highly
modified),Hirudinaria-fresh water leech

Archiannelida
 They are exclusively marine
 Cephalisation absent
 Parapodia and seate absent
 Clitellum absent
 Unisexual
 LARVA KNOWN AS LOVENS LARVA
 External segmentation is not very distinct
 Ex. Polygordius- connecting link between annelida
and mollusca (living fossil)

Special Points
 IN NEREIS PARAPODIA SERVES THE DUAL
PURPOSE OF LOCOMOTION AND RESPIRATION
SPECIAL ORGAN OF RESPIRATION LACKS IN
NEREIS
 FOUR PAIRS OF TUBULAR HEART PRESENT IN
EARTHWORM

Phlum annelida

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Phlum annelida