In physiology, respiration is the movement of oxygen from the outside environment to the cells within tissues, and the removal of carbon dioxide in the opposite direction. In these slides you will get to know about Physiology of Respiration in Invertibrates.

1. Physiology of
respiration in invertebrates
20-pzo-002
VICTORIA MAUREEN.A

2. SYNOPSIS
Introduction
History
Respiratory organs of invertebrates
1. Trachea and spiracles
2. Gill
3. Book lung
4. Book gills
Respiration in
1. Protozoa
2. Porifera
3. Coelenterates
4. Aschelminthes and platyhelminthes
5. Annelids
6. Arthropoda
7. Mollusca
8. Echinoderm
Respiratory pigments
Functions of respiration
Videos
Question bank
Reference

3. INTRODUCTION
• The process of gas exchange in the body, called
respiration. The act of inhaling and exhaling air in
order to exchange oxygen for carbon dioxide
• The process of inhalation of oxygen and
exhalation of carbon dioxide is known
as respiration.
• There are two types of cellular respiration
aerobic and anaerobic. One occurs in the
presence of oxygen (aerobic), and one occurs in
the absence of oxygen (anaerobic).

4. HISTORY
• Marcello Malpighi (1628-1694) was an
Italian scientist who found the
anatomical basis of respiration, He
was one of the first biologists to make
use of the newly invented microscope
and is best known as the discoverer of
the pulmonary capillaries and alveoli.
• Henri Dutrochet, a French physiologist
who term 'respiration'. He also
discovered and named the process of
osmosis (passage of solvent through a
semipermeable membrane) that
occurs at cellular level in both plants
and animals.

5. Respiratory organs of invertebrates
Trachea
• This respiratory organ is a hallmark of
insects.
• It is made up of a system of branching tubes
that deliver oxygen to, and remove carbon
dioxide from, the tissues,
• The smallest tubes, tracheoles, penetrate
cells and diffuse water, oxygen, and carbon
dioxide.
• Tracheae are a system of tiny tubes that
permit passage of gases into the interior of
the body.
• Tracheal systems are highly efficient for
these small, terrestrial animals.
• The pores to the outside, called spiracles,
are typically paired structures, two in the
thorax and eight in the abdomen. Periodic
opening and closing of the spiracles prevents
water loss by evaporation,

7. Gills
• Many invertebrates use gills as a major means
of gas exchange
• Gills are branching organs located on the side
of heads that have small blood vessels called
capillaries. As the organism opens its mouth,
water runs over the gills, and blood in the
capillaries picks up oxygen that’s dissolved in
the water.
• Gills consist of plate-like structures called
filaments that are covered by an array of
lamellae enclosing a capillary blood network
• Oxygen-rich water passes through the narrow
channels formed by the lamellar layers, where
oxygen diffuses into the capillaries. The
densely packed lamellar structure is
advantageous because it provides a large
surface area for oxygen transfer.

8. Book lung
• It is a form of respiratory organ found
in certain air-breathing arthropods
(scorpions and some spiders).
• Each book lung consists of a series of
thin plates that are highly vascular
(i.e., richly supplied with blood) and
are arranged in relation to each other
like the pages of a book.
• These plates extend into an internal
pouch formed by the external
skeleton that opens to the exterior by
a small slit. This provides an extensive
surface for the exchange of oxygen
and carbon dioxide with the
surrounding air. There are four pairs
in scorpions and up to two in spiders.

10. Book gills
• It is believed that book lungs evolved from book gills. Although they have a
similar book-like structure,
• book gills are external, while book lungs are internal. Both are considered
appendages because book lungs develop from limb buds before the buds
flatten into segmented lamellae.
• Book gills are still present in the marine arthropod Limulus (horseshoe
crabs) which have five pairs of them,
• the flap in front of them being the genital operculum which lacks gills.

11. PROTOZOA
• Single-celled organisms,
such as bacteria and
protozoa, are in constant
contact with their external
environment. Gas
exchange occurs by
diffusion across their
membranes. The
respiratory gases may
diffuse in and diffuses out
trough the general body
surface, there are no
special organ for
respiration.

12. PORIFERA
• In sponges, the special
respiratory organs are absent
• Gaseous exchange occurs by
simple diffusion between the
cells of sponges and the
current of water
• Oxygen dissolved in water is
taken in by diffusion through
the general body surface and
carbon di oxide is given out
• Amoebocytes distributes
oxygen with in the
mesenchyme and carry away
carbon di oxide

13. COELENTERATES
• In coelenterates, the special
respiratory organs are absent
• Their body cells are ore or less
directly exposed to the
environment, both cell layers
absorb oxygen from and
expel carbon dioxide into the
surrounding water.
• the oxygen is absorbed into their
first layer of skin, called the
ectoderm.
• Then, it goes through to the second
layer, called the endoderm. The
oxygen molecules are used and
excess oxygen is released as carbon
dioxide.

14. ASCHELMINTHES AND PLATYHELMINTHES
• respiratory organs are absent The body
walls of aschelminthes are very thin and
thus it acts as their respiratory system.
• In living flatworms and roundworms, the
exchange of gases takes place through
general body surface
• In parasitic form, there is no exchange of
gases. Endo parasites lives n almost oxygen
free environment and fulfills its relatively
less energy requirements by anaerobic
respiration
• Flatworms are small, literally flat worms,
which 'breathe' through diffusion across
the outer membrane. The flat shape of
these organisms increases the surface area
for diffusion, ensuring that each cell within
the body is close to the outer membrane
surface and has access to oxygen.

15. ANNELIDA
• Respiration in annelids occurs primarily through
their moist skin, although certain species have
evolved specialized gills or use paired
projections called parapodia in gas exchange.
• In earthworms the respiration mainly occurred
or performed through skin the called as
cutaneous respiration
• The blood of earthworm contains a respiratory
pigment – Haemoglobin in a dissolved state in
its plasma
• The epidermis of the body wall acts as a
permeable membranes through which the
atmospheric oxygen diffuses in its capillaries
and combine with haemoglobin to form
oxyhaemoglobin

16. • The oxyhaemoglobin is circulated by
blood into the tissues where oxygen
tension is very low and carbon di oxide
tension is high
• The oxyhaemoglobin breaks up to release
oxygen to the tissues and haemoglobin in
a reduced state
• Now carbon di oxide from tissue diffuses
into the blood due to its high tension. The
carbon di oxide is carried by the blood
generally in a dissolved condition and
when it reacts to the epidermal capillaries
it diffuses from the blood to the
atmosphere due to low tension

17. ARTHROPODA
• Aquatic arthropods possess gills for respiration and are
covered by the exoskeleton, which is thin in this area
and not a barrier to the exchange of gases.
• Terrestrial arthropods possess tracheae and book lungs
as respiratory organs. The small, external openings
(spiracles) reduce water loss, the chitinous lining
prevents collapse
• Book lungs are chitin-lined internal pockets containing
many blood-filled plates over which air circulates. Most
spiders possess tracheae and book lungs, but large
spiders (such as tarantulas) and scorpions possess book
lungs alone.

18. • The respiratory system of cockroach
is very well developed to
compensate the absence of
respiratory pigment in the blood
• Ten pairs of spiracles or stigmata are
present on the lateral side of the
body. The largest first pair is present
on the mesothorax. The second pair
is on the metathorax and the rest
eight pairs are on the first eight
abdominal segments.
• the haemocoel contains a network
of elastic, closed air tubes or
tracheae. Three longitudinal
tracheal trunks are present on each
side of the abdominal cavity.

19. MOLLUSCA
• Basically all molluscs breathe by
gills that are called ctenidia (comb-
gills) because of their comb-like
shape.
• A ctenidium is shaped like a comb or a
feather, with a central part from
which many filaments or plate-like
structures protrude, lined up in a row
• In land snails and slugs, mantle cavity
has evolved into primitive lung
• the mantle cavity forms a pulmonary
chamber, the inner surface of which is
highly vascularised.
• Many molluscs have a siphon which
expels water and wastes

20. ECHINODERMS
• In echinoderms (starfish, sea urchins, brittle
stars), most of the respiratory exchange occurs
across tube feet (a series of suction-cup
extensions used for locomotion).
• Echinoderms typically breathe and respire by the
simple diffusion of gases like oxygen and carbon
dioxide in and out of their body cell membranes.
• However, this exchange is supplemented by
extensions of the coelomic, or body-fluid, cavity
into thin-walled “gills” or dermal branchiae
that bring the coelomic fluid into close contact
with seawater.
• Respiratory tree is the branches of cloaca just
inside the anus with the help of the drawing
water through the anus and then expelled

21. Respiratory Pigments in Invertebrates
• In order to facilitate the transport of oxygen to
different parts of the body, most animals have
developed respiratory pigments.
• In general, respiratory pigments are coloured proteins
that contain a metallic element in their constitution
and have the property of forming loose combination
with oxygen and sometimes with carbon dioxide.
• Four different (biochemically) respiratory pigments are
recognized – haemoglobin, chlorocruorin,
haemocyanin, and haemerythrin. Even in the same
phylum there may be several distinct pigments

22. • Haemoglobin:
It is the most efficient
respiratory pigment. It is
widely distributed in the
animal kingdom, starting
from some protozoa like
Paramoecium to almost all
vertebrates except eel larvae
and some Antarctic fishes.
Some invertebrate phyla viz.,
Porifera, Cnidaria and
Ctenophora, totally lack it

23. • Haemocyanin:
Among various copper-
proteins occurring in nature,
only haemo cyanin can
reversibly combine with
oxygen and thus, serves as a
transport pigment. It is
found in Chitons, some
gastropods and
cephalopods amongst the
molluscs and in crustaceans
and Limulus amongst the
arthropods. It always remain
dissolved in the plasma.

24. • Chlorocruorin:
This green coloured
metalloprotein is found in
the plasma of certain
polychaet families. It is a
metalloprotein with the
metal being iron (Fe++); the
metalloporphyrin is similar
to heme of haemoglobin
except that one vinyl (CH =
CH2) group is replaced by
formyl (0=CH) group in
Chlorocruorin. The
porphyrin is called
chlorocruoheme.

25. • Haemerythrin:
This violet coloured pigment is
found inside the corpuscles of
animals ex.polychaete worm
Magelona. It is also an iron
containing metalloprotein but
has no porphyrin.
• Pinna globin:
This brown coloured,
manganese containing
pigment is present in the
plasma of Pinna.

26. Functions of respiration
• Delivers oxygen to the cells in your body.
• Removes waste gases, including carbon
dioxide, from the body when you exhale.
• Breathing – movement of air
• Sound Production
• Olfaction, or Smelling, Is a Chemical Sensation

28. Question bank
PART-A
1. Define respiration?
2. What are the types of respiration?
3. Name the Respiratory organs of invertebrates?
4. What is Trachea?
5. What are tracheoles?
6. What are Spiracles?
7. Define Gills?
8. What are gill filaments?
9. What is book lung?
10. What are book gills?
11. Define diffusion?
12. What is the role of Amoebocytes in poriferan respiration?
13. Define cutaneous respiration?
14. What is oxyhaemoglobin ?
15. What is ctenidia ?
16. What is dermal branchiae?
17. What is Respiratory tree ?
18. What is respiratory pigments?
19. What are the types of respiratory pigment?

29. PART-B
1. Explain the mechanism of respiration in insects?
2. Explain the mechanism of respiration in annelids?
3. State the functions of respiration?
4. Give an account of respiratory organ “book lung”?
PART-C
1. Explain the types of respiratory organs in invertebrates ?
2. Give a detailed account of types of respiratory pigments?

30. References
• https://byjus.com/biology/respiration-cockroach-earthworm
• https://www.notesonzoology.com/cockroaches/process-of-
respiration-in-cockroaches-invertebrates/1989
• https://www.britannica.com/science/respiratory-system/Basic-
types-of-respiratory-
• https://www.webmd.com/lung/picture-of-the-trachea
• https://www.toppr.com/guides/science/respiration-in-
organism/respiration-in-other-animals/
• https://phylumrespiratioryexamin.weebly.com/porifera.html
• https://www.vedantu.com/question-answer/respiration-occurs-
in-annelids-by-a-skin-b-gills-class-11-biology-cbse-
6010e70fdfcfb40cf08fd05c
• Book: Manual of zoology part 1 Invertebrata
Volume 1 and 2
BY- M. Ekambaranatha Ayyar T.N Ananthakrishnan