The document provides a detailed overview of the phylum Annelida, which includes segmented worms such as polychaetes, oligochaetes, and hirudinea, encompassing over 12,000 species. It describes the anatomical features, reproductive systems, and classifications of these worms, highlighting differences among the three major classes, including their habitats and physiological traits. Key characteristics include bilateral symmetry, a coelomic cavity functioning as a hydrostatic skeleton, and distinct respiratory systems adapted to their environments.

1. ANNELIDA
(Segmented Worms)
Nolie Calidro Gerardo
Nicole Calidro
Mariano Marcos State University
COLLEGE OF TEACHER EDUCATION

2. • Annelida came from the Latin word “annelus” means little
ring
• Over 12,00 known species are grouped into 3 classes:
Polychaetes, Oligochates and Hirudinea
• The most highly advanced and most successful of the
various “worms phyla
• Symmetry bilateral; three germ layers
• Soft bodied animals in which the large fluid filled coelom
serves as a hydrostatic skeleton

3. 3 MAJOR CLASSES
CLASS POLYCHAETA
• From the Greek word poly (many) and chate (spine or
bristle)
• Largest class of annelids with over 8,00 species
• Live in ocean
Features
• Long, slender, greenish body is rounded and flattened
vertically and composed of 200 or more similar somites
• Distinct head is formed by prostomium and peristomium

4. • The protosmium bears 2 short protosmial tentacles,
pulps and eyes
• The peristomium surrounds the ventral mouth and
carries 4 pairs of peristomial tentacles
• The anus is the first somite on which are two soft
sensory anal carri
• The body was covered by cuticle
• Within the body wall was coelemic cavity

5. EXAMPLES

6. Digestive System
• Includes mouth, pharynx, esophagus, stomach, intestine and
anus.
Circulatory System
• Comprised a dorsal and ventral vessel
• The plasma is red containing dissolved hemoglobin and
amoebocytes
• Circulation results from peristaltic contraction of dorsal
vessel

7. Respiration
• Effected by capillaries in the parapodia and body wall
Excretion
• Performed by paired nephridia
Nervous System
• Includes brain, nerves to the bead and tentacles, connectives
to the mid ventral nerve cord and a pair of ganglia and
lateral nerves
Reproduction
• Sexes are separate and gonands are present only on
breeding season
• Fertilization occurs in the sea
• Allows epitoke

8. SUB CLASS
1. Errantia
• Those are free living and crawl or swim
• Have body of similar segments with well developed
paopodia
• A muscular eversible proboscis with teeth or jaws
• Distinct head and organs
Alitta succinea
(known as the pile worm or clam worm)

9. 2. Sendentaria
• Those confined permanently to tubes, often with
the body divided into 2 or more regions or tagma
• Without a protrustible proboscis with jaws
• With a reduced head
Cirratulus cirratus

10. 3. Archiannelidda
• Small in size; segmentation chiefly internal
• Parapodia and setae usually absent
• Nervous system in epidermis; usually dioecious;
gonads numerous
• Marine
Polygordius (polychaete genus)

11. CLASS OLIGOCHAETA
From the Greek word oligos (few) and chaeta (spine), have few
setae per segment
• Live in fresh water and moist soil
• 3,100 species
External Features
• The body is long and cylindrical bluntly tapered at each
end
• There’s no distinct head
• The mouth is the first somile and the anus is the last somile
• The clitellum that secrets material forming cocoons to
contain eggs

12. • A mature worm is divided into 115 200 somites
• Dorsal pore connect the body cavity and
exterior
Earthworm

13. Internal Structure
• The space between of the two concentric tubes, the outer
body wall and the digestive tract is the body cavity or coelom
• The coelom and all organisms within it are covered by
peritoneum

14. Digestive System
• Consist of the mouth, pharynx, esophagus, crop, intestine
and anus
• The intestine is thin walled and bulges laterally in each
somile and its dorsal wall carries an infolded thyposole
for absorption of food

15. Circulatory System
• Blood consist of fluid plasma that contains
amoebocytes
• Plasma is colored red by hemoglobin
• Blood circulate in a system of closed blood
vessels

16. Respiration
• No organized respiratory system
• Through epidermis
Excretory System
• Every somile except the first three and last has a pair
of nephridia
• Nephridia act much like tubules in human kidney

17. Nervous System
• A pair of supra pharyngeal cerebral ganglia, the
brain
Reproduction
• Monoecious; both male and female sex organs are
ventral and anterior
• Males sex organs: 2 pairs of minute testes, 2 sperm
funnel, ductus efferens, ductus deferens, malepore and
seminal vesicles
• Female sex organs includes ovaries, oviduct funnels,
oviduct and seminal receptacles

18. ORDER
• Lumbriculida
Lumbriculus variegatus

19. • Monilogastrida
Moniligaster

20. • Haplotaxiada
Sub-Orders
A. Haplotaxina
B. Tubifiana
C. Lumbricana
haplotaxis
Tubifex
megascolides

21. CLASS HIRUDINEA
• Aquatic or terrestrial worms
• Have enlarged terminal suckers for locomotion
and attachment
• Most are fluid feeding
• Blood sucking group( most)
• Scavengers, predators, or parasitic
• The body is divided into 34 somites
• 500 species

22. Features
• The body of a leech at rest is long or oval in outline
• Usually flat dorsoventrally and very flexible maybe
stretched
• Posterior end is a rounded sucker
• Another sucker surrounds the mouth at the anterior
end in many species

23. Digestive system
• Includes the mouth, pharynx, short esophagus, 20 pairs of
lateral caeca, a slender intestine, short rectum
Circulatory System
• Longitudinal sinuses , dorsal, ventral and lateral, with many
cross sections
• Pulsations in some of three cause the blood to circulate

24. Respirations
• A network of capillaries beneath he epidermis
Excretion
• It pairs of peculiar nephridia
• Sometimes branched and sometimes have closed
nephrostomes
Nervous Sysem
• Pair of dorsal ganglia and paired connectives to the
ventral nevre cord
• Four of the anterior ganglia
• Seven at he posterior end are fused

25. Reproductive Sytem
• Male reproductive system includes 4 to 12 pairs of testes
beneath the crop, ductus deferens running anteriorly
• 2 ducts enter a median penis to which accessory glands
connect
• The penis is within the general pore
• Female reproductive system includes 2 ovaries and oviducts
joining a single albumen gland and a median vagina that
opens just behind the male pore
• Sexes are united

26. Image Source: Google Images