Answer in 15 minutes
Write true or false (with correct)
1- Metazoa Included Parazoa and metazoa .
2- Metazoa the animals have unicellular body.
3- Eumetazoa have bilateral symmetry only .
4- Parazoa cellular organization .
5- Parazoa are not differentiated cells in layers.
6- Parazoa have true tissues .
7- As example of parazoa are clams .
8- Triploblastic have 2 layers .
9- Eumetazoa divided to triploblastica and uniblastica .
10- Diploblastica have ectoderm , endoderm & mesoderm tissues.
11- Diploblastic have three tissues .
12- Triploblastic is important for movement .
13- Body cavity lying between the body wall and the internal organs .
14- Body cavity may be rich of Mesenchyme cells .
15- Bilateral animals having distinct body cavity .
16- for example of pseudocoelomates Acanthochiton .
17- Mesenchyme cells are occupying the space between the body wall and the
anus of the animals .
18- The body cavity derived from the gut of the embryo .
19- This cavity is lined by mesodermal epithelium .
1
Answer in 15 minutes
Write true or false (with correct)
20- Ceolom is Internal fluid-filled cavity .
21- Ceolomates have body cavity lined with mesoderm .
22- pseudocoelomates have body cavity partially lined with mesoderm .
23- Schizocoelous are liquid masses of mesoderm split to form the coelomic
cavities As the archenteron .
24- Enterocoelous are not mesoderm buds off from the wall of the
archenteron and hollows to become the coelomic cavities .
2
3
Lecture 2
4
Syllabus
•Introduction
•Phylum: Annelida (General charactes)
•Nereis
•Allolobophra caliginosa
•Hirudo medicinalis
•Phylum: Arthropoda (General charactes)
•Astacus fluviatulis & Neptunus pelagious
•Daphnia, Cyclops, Balanus
•Scolopendra morsitans, Lycosa ferox
•Phylum: Mollusca (General characters)
•Acanthochiton spinigira, Helix pomatia
•Loligo peadlii, Anodonta sp.
•Phylum: Echinodermata (General characters)
•Astropecten sp.
5
6
Aim










What do know about Segmented worms ?
What do know about Segmentation ?
What do know about Symmetry ?
What do know about Organ Systems ?
What do know about Mechanism/Mode of Locomotion ?
What do know about Typhlosole ?
What do know about Polychaeta ?
What do know about Body wall in Polychaeta ?
What do know about habitat in Polychaeta ?
What do know about Organ Systems in Polychaeta ?
7
Remember
8
Phylum Annelida
General characters
9
Phylum Annelida
General characters

Segmented worms







15,000 species
Triploblastic
Protostome
Bilateral symmetry with cephalisation obscured in
some species
Internal body space is partitioned ( - ‫فصل بحاجز‬
‫ قسم‬by septae
Marine, freshwater and terrestrial (in moist
soil/humus) species
Cutaneous respiration

Skin is highly vascularised and must stay moist
10
Phylum Annelida
General characters
Segmentation

is the subdivision of
the body into segments


Two advantages result from embryonic segmentation
1- Each segment
may develop a
more or less
complete set of
adult organ
systems .
2-Locomotion is far
more effective
because of
increased flexibility
of movement .
11
Phylum Annelida
General characters
Segmentation
12
Phylum Annelida
General characters
Segmentation
 body
space is partitioned by septae
13
Phylum Annelida
General characters
Symmetry
14
Phylum Annelida
General characters
Symmetry
radial symmetry
the parts of the body are
arranged around a central
axis
bilateral symmetry
the body has a right and left
half that are mirror images of
each other
1-Allows different organs to be located in different parts of the body.
2-Ultimately led to cephalization.
3-Evolution of a definite head and brain area.
15
Phylum Annelida
General characters
systems
1- Muscular
System
2Integumentary
System
3- Nervous
System and
Sensory organs
4- Circulatory
System
5- Respiratory
System (gas
exchange)
6- Digestive
System
(food/water
supply)
7- Immune
System
8- Excretory
System
9- Reproductive
System
16
Phylum Annelida
General characters
1- Muscular System
1-Both longitudinal and circular
muscle fibers Allows for
coordination of propulsive
muscular waves in body wall;
peristalsis ( ‫حركات تقلصية متتابعة‬
‫فى قناة أو انبوب ( فى الجسم‬
‫لدفع الغذاء أو الفضالت‬
2-Special muscles attached to setae
to move setae
3- In polychaetes, oblique muscle
groups run into the parapodia for
movement
Note
Mechanism/Mode of
Locomotion
peristalsis involving the
alternating contractions of
longitudinal and circular
muscle
* layers to change the shape
of individual segments
* Burrowing and creeping
using peristalsis and/or
parapodia
17
Phylum Annelida
General characters
Integumentary System (skin)




1- Cellular epidermis that secretes a mucus
2-Thickened, non-living transparent cuticle
3-Cilia present in many forms chitinous setae often present; setae absent
in leeches; greater number of setae in
4-As compared to oligochaetes
Coelom is fluid-filled space

Allows for coordination of propulsive muscular waves
18
Phylum Annelida
General characters
Integumentary System (skin)
19
Phylum Annelida
General characters
Note
Not all organ systems
are metameric (‫ينقسم إلى‬
‫مفصصات أو أجزاء متماثلة‬
‫متتابعة علىامتداد الجسم كجسم‬
‫)دودة األرض‬
For example: the
digestive system
extends the length of
the organism and is
differentiated along its
length .
20
Phylum Annelida
General characters
21
Phylum Annelida
General characters
Nervous System





1- Consists of a brain .
2- cerebral ganglia with two
fused ventral nerve cords .
3- various ganglia similar to
arthropods .
(ganglion in each segment
(metameric))
4- leeches have an anterior
brain of six pairs of fused
ganglia and a posterior brain
of seven pairs of fused
ganglia
.
22
Phylum Annelida
General characters
Sensory Organs
sensory tentacles
 Palps
 Eyespots in polychaetes
 (Especially on prostomium)

23
Phylum Annelida
General characters
Circulatory System
1- closed circulatory
system that is
segmentally arranged
with aortic arches
(“hearts”)
 2- and ventral and dorsal
blood vessels
surrounding pharynx for
circulating blood
 3- blood contains
respiratory pigments
including hemoglobin
 4- Blood with haemoglobin
as O2-carrying molecule

24
Phylum Annelida
General characters
Respiratory System (gas exchange)
gas exchange by simple
diffusion = cutaneous
respiration and/or
 Gills in some polychaetes
and/or
 parapodia in polychaetes
act as gills = example of
convergent evolution to
appendages
 and specialized gills seen in
arthropods

25
Phylum Annelida
General characters
Digestive System (food/water supply)




Complete digestive system
with mouth and anus, not
segmentally arranged
well muscularized pharynx in
oligochaetes
Crop for storage, Gizzard for
grinding and Typhlosole
with increase surface area for
absorption in oligochaetes
In oligochaetes, ingested soil
may contain high levels of
calcium; calciferous glands
along esophagus secrete
calcium ions into gut to
reduce calcium ion
concentration and maintain
acid-base balance in blood
26
Phylum Annelida
General characters
Digestive System (food/water supply)




In tube worm polychaetes,
specialized feathery arms or
radioles use ciliary
‫هدبي‬action
Mucous to trap food particles of
a digestible size
leeches are parasitic, but also
predaceous and scavenging
‫تنظيف‬on fluids and tissues
terrestrial leeches feed on
insect larvae, earthworms and
slugs
27
Phylum Annelida
General characters
Digestive System (food/water supply)
Typhlosole
28
Phylum Annelida
General characters
Immune System

Ameobocytes found in blood
29
Phylum Annelida
General characters
Excretory System





Well developed metanephridia in most
segments that involves removal of
wastes from the blood and the coelom .
Generally have metanephridia; some have
protonephridia each metanephridium has
a ciliated funnel or nephrostome that
leads by a small ciliated tubule through
the septum in to the segment behind to a
nephric tubule that empties into a
bladder and waste is excreted out a
nephridiopore (opening) .
Aquatic annelids secrete ammonia .
Terrestrial oligochaetes secrete less
toxic urea .
Osmoregulation occurs via the body
surface and the nephridia .
30
Phylum Annelida
General characters
Reproductive System
-Monoecious in oligochaetes and leeches
(Hirudinae) with internal fertilization and
direct development (no larval stage =
juvenile worms look like mini adults)

-Dioecious ( ‫ثنائي البيت اي ان اعضاء‬
‫التذكير التناسلية في فرد واعضاء التأنيث‬
)‫ التناسلية في فرد اخر‬in polychaetes with
external fertilization and formation of a
trochophore larva .
-Asexual = most highly organized animals
capable of complete regeneration.
- This ability varies considerably within the
phylum.
- Evolutionarily, regenerative capability has
been lost in many species.
-Both anterior (tail to head) and posterior
(head to tail)

-Segment regeneration has been shown in
some species.

31
Phylum Annelida
General characters
Reproductive System

Hermaphrodites - with
cross fertilization
Clitellum is a special
region at the anterior end
of the worm that
1-secretes a mucus
cocoon,
2-both during mating (to
hold the worms together)
3-protective coat around
eggs
 Trochophore is typical
larval stage

32
Phylum Annelida
General characters
Major Classes
Class:
Hirudinea
Class:
Oligochaeta
Class:
Polychaeta
33
Phylum Annelida
General characters
Polychaeta










1- (pol'e-ke'ta) (Gr. polys, many, + chaiti?, long
hair).
2- About 5300 species.
3- Segmented inside and out; parapodia used in
locomotion with many large number of
chitinous bristles setae
4- Distinct head with eyes
5- palps, and tentacles
6- No clitellum
7- Separate sexes
8- Trochophore larva usually present
9- Mostly marine.
10- Examples: Nereis
34
Phylum Annelida
General characters
Polychaeta
Well - developed head .
 *Prostomium is well equipped
with sensory and feeding
structures .

Jaws
Teeth
Postomial tentachels
Peristomial palps
Peristomial tentachels
35
Phylum Annelida
General characters
Polychaeta
Body wall

It consists of an outer cuticle
which is secreted by :
The cells of the
hypodermis just beneath
it .
several muscular layers
under the hypodermis
36
Phylum Annelida
General characters
Polychaeta
1- Bristle worms
 2- Mostly marine
 3- Most free-living (living in
substrate or free-swimming),
but some live in mucussupported tubes that are
surrounded by substrate
 4-Many are active predators,
while others are filter
feeders

37
Phylum Annelida
General characters
Polychaeta
Habitat

Many crawl on or burrow
in the seafloor.
 A few drift and swim in
the plankton.
 Polychaetes include
carnivores, scavengers,
and planktivores.
 The brightly colored
fanworms trap planktonon
feathery tentacles.
38
Phylum Annelida
General characters
Polychaeta
systems
Nervous
System
Digestive
system
Circulatory
System
Respiratory
system
Excretory
System
Reproduction
39
Phylum Annelida
General characters
Polychaeta
Nervous System














1-dorsal brain
(brain is fund above the pharynx in the head whis is consists of a pair of supra
pharynx geal ganglia .
- it is connected with a pair of sub pharyngeal ganglia by acircumpharyngeal
commissure on either side which from aring around the pharynx).
2- ventral, with a pair of ganglia
3-solid nerve cord, with ganglia in each segment.
4- Endocrine- hormones secreted by nervous system.
The brain gives off:A- An optic nerve to each eye
B- Palpal nerve to each palpus
C- Atentacular nerve to each group of tentacles.
5- Three pairs of nerves arise from each of ganglia of the ventral nerve chain
- One pair to
1- the parapodia
2- the anterior segment
3- the muscles of the segment
40
Phylum Annelida
General characters
Polychaeta
Nervous System
41
Phylum Annelida
General characters
Polychaeta
Digestive system
Mouth
Is located
just below
the
prostomium,
but in front
of the
modified
segments peristomium
Esophagus
Is
surrounde
d by
digestive
glands
Pharynx
Intestine
Is
equipped
with
pincerlike jaws
1-Straight
2-finally
opens
with anus
in the
anal
segment
42
Phylum Annelida
General characters
Polychaeta
Digestive system
1- The mouth opens into the pharynx which
forms assort of proboscis .
 (This is accomplished by protractor and
retractor muscles ).
 2- The pharynx leads into a slender
esophagus which have digestive gland .
 3 - Straight stomach following the esophagus

it extending to the anus
.
43
Phylum Annelida
General characters
Polychaeta
Digestive system

Feeding:

Clamworms (Nereis) crawl
about on marine surfaces
hunting for food using
well-developed sensory
structures. Once located,
prey are seized with
chitinous jaws on a rapidly
everted, muscular pharynx
44
Phylum Annelida
General characters
Polychaeta
Digestive system
•
Digestive
system
•
Includes a
muscular
pharynx
that can be
everted
through
the mouth
Note
45
Phylum Annelida
General characters
Polychaeta
Circulatory System
Closed system
 Use hemoglobin as oxygen carrier.

46
Phylum Annelida
General characters
Polychaeta
Circulatory System
1- The blood is contained in contractile
tube ( the blood vessels ).
 2- There is a dorsal vessel , that lies
between the two dorsal longitudinal
muscles bands ( which carried blood
anteriorly ).
 3- A ventral vessel below the intestine
which carries blood posteriorly.
 4- In each segment , the longitudinal
vessels are connected on either by right
and left transverse vessels to form

networks of capillaries in parapodia
.
47
Quiz
48
Answer
1- Parapodium
11- Ventral blood vessel
2- Coelom
12- Circular muscle
3- Dorsal blood vessel
13- Cuticle
4- Intestine
14- Nephridium
5- Longitudinal muscle
15- Nephridiopore
6- Capillary ped in parapodium
16- Setae
7- Notopodium
8- Neuropodium
9- Transverse parapodial muscle
10-Venteral nerve cord
49
Phylum Annelida
General characters
Polychaeta
Respiratory system
•
•
Although many of the
smaller polychaetes lack
respiratory structures, the
larger one do possess gills
Gills are usually
modifications of the
parapodia
50
Phylum Annelida
General characters
Polychaeta
Excretory System
Every segment contains a pair of
nephridia except the peristomium and
the anal segment .
 Each nephridium opens into the
coelomic cavity by means of a ciliated
funnel.
 Each nephridium passes posteriorly
through the septum into the following
segment. Where it forms coiled tube .
 It opens at the base of aparapoium on
the ventral surface through
nephridiopore .

51
Phylum Annelida
General characters
Polychaeta
Reproduction








1- Sexes are separate.
2- No well _ defined gonads are present but
during breeding season ova or spermatozoa
arise from the wall of the coelom in each
segment except near the anterior end.
3- At this time the worm is differentiated into 2
regions:
An anterior atoke.
A posterior epitoke which contains the gonads.
4- The specialized worm is called aheteronereid.
5- Fertilization occurs (external ) in the open
water.
6- Trochophore larvae develop from the
fertilized eggs.
52
Phylum Annelida
General characters
Polychaeta
Reproduction
53
Phylum Annelida
General characters
Polychaeta
Reproduction

Epitoky
 Morphological changes
that take place in many
polychaetes associated
with the reproductive activity
in tube-dwelling species
 At breeding time, many
morphological changes
associated with swimming
allow the worms to leave their
tubes and swarm to the
surface of sea for mating
54
General view
55
Quiz















1- Annelida are ……………. , ………….. , ………… and ……… worms .
2- What the meaning of cutaneous respiration ?
3- What the meaning of Segmentation ?
4- What the advantages result from embryonic segmentation ?
5- Body space is partitioned by …………… .
6- What the meaning of Symmetry ?
7- Compare between two type of Symmetry ?
8- Symmetry are ………………… and ………….. .
9- What the important of Symmetry ?
10- What are the systems of Annelida ?
11- Both longitudinal and ……………………………..allows for
coordination of propulsive muscular waves in …………………………. .
Special muscles attached to …………. to move it .
12- What are the mechanism of locomotion of Annelida ?
13- Illustrate Integumentary System ?
56
14- ……… epidermis that secretes a …….. .
Quiz











15- ……………….. transparent cuticle .
16- setae absent in …………… .
17- Coelom is ……………….. Space .
18- Not all organ systems are …………….. .
19- Illustrate the nervous system with drawing ?
20- leeches have an …....... brain of ……… pairs of fused
ganglia and a …… brain of …… pairs of fused ganglia .
21- What are the sensory organs of Annelida ?
22- Circulatory System in Annelida is …………… .
23- ventral and dorsal blood vessels surrounding
……….. for circulating ………… .
24- Blood contains
…………………………………..including hemoglobin .
25- Blood with hemoglobin as O2-carrying ……….. .
57
Quiz












26- Gas exchange by simple …………… .
AS
27- ……………. in some polychaetes .
Respiratory
28- parapodia in polychaetes act as ……………. .
System
29- ………………………seen in arthropods .
30- A meobocytes found in ……………… .
31- A meobocytes act as ……………. System .
32- ……………… digestive system with mouth and anus, not
…………… arranged .
33- well muscularized pharynx in ……………. .
34- Crop for ………, Gizzard for ……. and Typhlosole with
increase surface area for ………………. in oligochaetes
35- In oligochaetes what is the function of calciferous glands ?
36- leeches are ………….
37- Terrestrial leeches feed on …………….. , …………………..
and …………….. .
58
Quiz













38- Aquatic annelids secrete ………….. .
39- Write short notes on excretory system ?
40- Type of sex in oligochaetes …………..
41- Type of sex in polychaetes ……….. with external fertilization and
formation of a ………….. larva .
42- Annelids are ……………… with cross fertilization .
43- …………….. is a special region at the anterior end of the worm .
44- What is the function of clitellum ?
45- ……………………. is typical larval stage
46- What are the major classes in Annelids?
47- Write short notes on the three major classes in Annelids (what are
you know about them ) ?
48- What the meaning of monoecious , dioecious ?
49- In polychaetes ……………………. used in locomotion with many
large number of ………………………setae
50- Write five characters of polychaetes ?
59
Quiz











51- What do you mean when you say Prostomium and what the function ?
52- Write short notes on habitat of polychaetes ?
53- What are the components of nervous system in polychaetes and can
you illustrate how the syrians of nervous is flow ?
54- Draw the nervous system ?
55- ………….. is located just below the prostomium, but in front of the
modified segments – peristomium .
56- …………. is surrounded by digestive glands .
57- ………………is equipped with pincer-like jaws
58- ………………… is straight , finally opens with anus in the anal segment
59- In polychaetes can you illustrate the way which any particles tack it to
arrange to anus ? ( with draw and the type of this particle )
60- Muscular pharynx exist in …………….. and can be everted through the
………………… .
61- Draw the circulatory system in polychaetes and illustrate each function
of vessels ?
60
Quiz





62- Every segment contains a pair of………….except the
peristomium and the anal segment .
63- Each nephridium opens into the coelomic cavity by means of
………………..
64- Each nephridium passes posteriorly through the ………. into the
following segment. Where it forms ……………….
65- Reproduction tack place in ……………….
66- Give notes about epitoky and the function of it ?
 Can
you give another example
of polychaetes with it systems?
 (search)
61
Quiz
What do you benefit in this lecture ?
(write in short point and we
will see it in the next lecture )
Prepare the next lecture please
62