Millar Harley Zoology INVERTEBRATES INTRODUCTION.pdf

1. INVERTEBRATES (Zool-02506)
3(2-1)
Presented by: Nabeel Tahir
M.Phil. Zoology
Class: ADP 5 Semester

2. Course Contents
•Introduction: Classification of organisms; evolutionary relationships and tree diagrams; patterns of
•organization.
•Animal-Like Protists: The Protozoa: Evolutionary perspective. Multicellular and Tissue Levels of Organization: Evolutionary perspective:
origins of multicellularity; animal origins.
•Phylum Porifera: cell types, body wall, water currents and body forms; reproduction.
•Phylum Cnidaria (coelenterata) the body wall and nematocysts; alternation of generations; reproduction and classification up to class.
•Phylum Platyhelminthes: classification up to class; the free-living flatworms and their organ systems.
•Aschelminths: Evolutionary perspective; general characteristics; classification up to phyla with external features.
•Molluscan Success: Evolutionary perspective: relationships to other animals; origin of the coelom; molluscan characteristics; classification up
to class.
• Annelida: The Metameric Body Form: Evolutionary perspective: relationship to other animals, metamerism and tagmatization; classification
up to class. Annelida:
•Arthropods: Blueprint for Success: Evolutionary perspective: classification and relationships to other animals; metamerism and tagmatization;
metamorphosis.
•Hexapods and Myriadpods: Insect behaviour; insects and human.
•Echinoderms: Evolutionary perspective: relationships to other animals; echinoderm characteristics; classification up to class.

3. Practical
•Study of Euglena, Amoeba, Entamoeba, Plasmodium, Trypanosoma, Paramecium as representative of animal like
protists. (Prepared slides).
•Study of sponges and their various body forms.
•Study of principal representative classes of phylum Coelenterata.
•Study of principal representative classes of phylum Platyhelminthes.
•Study of representative of phylum Rotifera, phylum Nematoda.
•Study of principal representative classes of phylum Mollusca.
•Study of principal representative classes of phylum Annelida.
•Study of principal representative classes of groups of phylum Arthropoda.
•Brief notes on medical/economic
•importance of the following: Plasmodium, Entamoeba histolitica, Leishmania, Liverfluke, Tapeworm, Earthworm,
Silkworm, Citrus butterfly.
•Preparation of permanent stained slides of the following: Obelia, Daphnia, Cestode, Parapodia of Nereis.

4. Recommended Books:
• Hickman, C.P., Roberts, L.S. and Larson, A. Integrated Principles of Zoology, 11th Edition (International),
2004. Singapore: McGraw Hill.
• Miller, S.A. and Harley, J.B. Zoology, 5th Edition (International), 2002. Singapore: McGraw Hill.
• Pechenik, J.A. Biology of Invertebrates, 4th Edition (International), 2000. Singapore: McGraw Hill.
• Kent, G.C. and Miller, S. Comparative Anatomy of Vertebrates. 2001. New York: McGraw Hill.
• Campbell, N.A. Biology, 6th Edition. 2002. Menlo Park, California: Benjamin/Cummings Publishing
Company, Inc

5. Classification of organism
• The study of kinds and diversity of organisms and the evolutionary
relationships among them is called systematics or taxonomy.
• The study of systematics gives the order and relationship
among the organisms. This relationship arises from evolutionary
processes.
• The organisms are organizes into groups (taxa). This grouping is
based on degree of evolutionary relatedness.

6. Some biologists differentiate b/w systematics
and taxanomy
• Systematics:(Gr. systema, system
+ ikos, body of facts)
• The arrangement of species into
evolutionary group.
• Taxonomy:(Gr. taxis,
arrangement + L. nominalis,
belonging to a name).
• The original description of
species.

7. A taxonomic hierarchy
There are two basis of taxonomic hierarchy:
Taxonomic hierarchy based on morphology
• Karl von Linne gave the modern
classification system.
• He belie ved that different species
could be grouped into same
categories.
• This grouping is based on the
similarities b/w them.
• The group of animal with similar
characteristics forms a Taxon e.g.,
house fly similar with other flies.
Taxonomic hierarchy based on evolution
• Von Linne did not accept evolution.
But his many grouping show
evolutionary relationship.
•Morphological similarities b/w two
animals have a genetic basis - it give
rise to common evolutionary history.

8. V
on Linne recognized five taxa and modern taxonomists use
eight. It is arrangement from broad to specific

9. Nomenclatur e
The assignment of a distinctnametoeachspecies called nomenclature..
There are two problems with common names.
• First, common names vary
from country to country even
region to region.
• So the there must be a system
of naming organisms. So
biologists may communicate
easily with each other.
•Second, a common name
often does not specify a
particular species.
•E.g., different kinds of
pillbugs & crayfish cannot be
differentiated easily, same class
(Crustacea) but diff. orders
(lsopoda & Decapoda,
repectively).

10. pill bugs

12. Molecular Approaches to Animal Systematics

13. Molecular approaches to animal systematics
• Molecular approaches includes study of molecules like proteins,
DNA, RNA of different species.
•These approaches provide information which is used for taxonomic
studies.
•For example, gene products (proteins) are same in certain animals i.e .,
show the closeness b/w animals.
•So we easily compare the sequence of amino acids and nucleotides of
various organism's through this techniques.
• In this way the constant mutation rate is seen. The constant
mutation of organism is called molecular clock.

14. Continued...
•Sequencing nuclear DNA and mitochondrial DNA (mDNA) helps
taxonomists to study the taxonomic relationships.
mDNA is useful in taxonomic studies because:
• Mitochondria have their own genetic system.
•They are inherited through cytoplasm, which means it comes from
mother. So we can check the maternal lineages.
• mDNA is in small quantity so it changes at a relatively constant rate.

15. Molecular Clock
• The molecular clocks used to determine rates of evolutionary
changes. This information helps us to fill the time gaps in the fossil
record.
Molecular clocks run at different rate and depends on:
• Sequence of amino acids in proteins.
• Sequence of bases in mDNA.
• Sequence of bases in nuclear DNA.
• Data from different evolutionary lineages.

16. Animal Systematics (Classification)

17. Animal systematics (classification)
•There are certain classification groups are made to classify them. As
follows:
• Monophyletic groups
• Polyphyletic groups
• Paraphyletic groups

18. 1. Monophyletic groups
• The groups showing similarities due to single ancestors are called
monophyletic groups. & the classification is monophyletic classification.
•The species should have single ancestral species. All the descendants
should arise from his single ancestral species.
• The taxonomists look for characters, (indicate relatedness), for
searching out monophyletic groups.
• A character is anything that has a genetic basis and can be measured
from an anatomical feature to a sequence of nitrogenous bases in DNA or
RNA.

19. 2. Polyphyletic groups
•The group showing similarities but have separate ancestors are
called polyphyletic groups.
•Each group has a single ancestor. Polyphyletic group indicate
insufficient knowledge of the group.

20. 3. Paraphyletic groups
•A group formed temporarily for some lineage is called
Paraphyletic groups.
•Paraphyletic groups are formed due to insufficient knowledge of the
group.
•Simply, taxonomic grouping that is derived from a single ancestor
but does not include all members of the family group is called a
Paraphyletic group.

22. Types of animal systematics
• There are certain disagreements are present in animal systematics &
these are:
• In the methods of investigation.
• In the use of data in describing distant evolutionary relationship.
• So, on thebasis of these differences two contemporary schools of
systematics exist:
• Evolutionary systematics (traditional approach)
• Phylogenetic systematics (cladistics)

23. 1. Evolutionary systematics
•The systematics in which evolutionary relationship are developed by study of fossils of
ancestors of closely related animals is called evolutionary systematics.
•Its basic assumption is that organisms closely are related to an ancestor.
•According to this there are two similarities b/w organism:
•Homologies: The resemblances that result from common ancestry are called homology. It is
called divergent evolution. E.g., wing of bird and arm of human.
•Analogies: The resemblances that result from organisms adapting under similar evolutionary
pressures are called analogy. It is called convergent evolution.E.g., wings of birds and insects.
•Evolutionary systematics can be shown on ph ylogenetic trees. The organisms are grouped
according to their evolutionary relation ships in phylogenetic tree.

25. 2. Phylogenetic systematics (cladistics)
•The development of evolutionary relationship among the organism on the
basis of studyof fossil, analysis and tests is called ph ylogenetic systema tics.
•The cladists are mainly check/study the genealogical relationship among monophylretic
groups of organisms and use more testing and analysis. Therefore it is more scientific than
evolutionary systematics.
•The cladists differentiate b/w homologies & analogies.
•However, they believe that homologies of recent origin are most useful in phylogenetic
studies.
•The cladists study two types of characters:
•Symplesiomorphies
•Synapomor phies

26. Symplesiomorphies
•(Gr. sym, together; plesio, near; morphe,
form).
•The characters that all members of a group
share are called basic characters or
Symplesiomorphies.
•These characters are homologies that
may indicate a shared ancestry.
•But they are useless in describing
relationships within the group.
•To decide what character is ancestral for a
group of organisms, cladists look for a related
group of organism, called an outgroup.
Synapomorphies
• (Gr. syn, together; apo, away; morphe,
form).
•Characters that have arisen since common
ancestry with the out-group are called
derived characters or synapomorphies.
• Simply, A character that can be used to
distinguish an animal from other
animals within group is called a
synapomorphies.

28. PATTERNS OF ORGANIZATION

29. Pattern of Organization
4 major types
• Symmetry
• Asymmetry
• Radial symmetry
• Bilateral symmetry

30. Symmetry:
• arranged around a point or an
axis
Asymmetry:
• The arrangement of body parts
without central axis or point
(e.g., the sponges)

31. Radial symmetry
• The arrangement of body parts
such that any plane passing
through the oral-aboral axis
divides the animal into mirror
images (e.g., the cnidarians).
• Radial symmetry can be
modified by the arrangement of
some structures in pairs, or
other combinations, around the
central axis
Bilateral symmetry
• The arrangement of body parts
such that a single plane passing
between the upper and lower
surfaces and through the
longitudinal axis divides the
animal into right and left mirror
images (e.g., the vertebrates)

32. Radial symmetry Bilateral symmetry

33. Organization of animal bodies based on
tissue layers and body cavities

34. Diploblastic Organization
• Cells are organized into tissues in most animal phyla
• Body parts are organized into layers derived from two embryonic tissue layers.
• Ectoderm- Gr. ektos, outside + derm, skin gives rise to the epidermis the outer
layer of the body wall
• Endoderm- Gr. Endo, within, gives rise to the gastrodermis that lines the gut
• Mesoglea- between the ecto and endo and may or may not contain cells
• Derived from ecto and/or endo
• Cells form middle layer (mesenchyme)
• Layers are functionally inderdependent, yet cooperate showing tissue level
organization i.e. feeding movements of Hydra or swimming movements of a
jellyfish

36. The Triploblastic (treis, three +blaste, sprout)
• Tissues derived from three embryological layers
• Ectoderm- outer layer
• Endoderm- lines the gut
• Mesoderm- meso, middle, Third layer between Ecto and Endo
• Give rise to supportive cells
• Most have an organ system level of organization
• Usually bilaterally symmetrical or evolved from bilateral ancestors
• Organized into several groups based on the presence or absence of body
cavity and for those that posses one, the kind of body cavity present.
• Body cavity- fluid filled space in which the internal organs can be
suspended and separated from the body wall

37. Body cavities are advantageous
1. Provide more room for organ development
2. Provide more surface area for diffusion of gases, nutrients, and
waste into and out of organs
3. Provide area for storage
4. Often act as hydrostatic skeletons (supportive yet flexible)
5. Provide a vehicle for eliminating wastes and reproductive products
from the body
6. Facilitate increase in body size

38. Acoelomate a, without+ kilos, hollow
• Mesoderm relatively solid mass
• No cavity formed between ecto and endo
• These cells within mesoderm often called parenchymal cells
• Parenchymal cells not speciallized for a particular fnc.

39. Triploblastic Pseudocoelomate pseudes, false
• Body cavity not entirely lined by mesoderm
• No muscle or connective tissue associated with gut
• No mesodermal

40. The Triploblastic Coelomate Pattern
• Coelom is a body cavity completely surrounded by mesoderm
• Peritoneum- mesodermal sheet that lines the inner body wall and
serosa (outer covering of visceral organs)
• Having mesodermally derived tissue (muscle, connective tissue)
enhances the function of all internal body systems.

42. Organization of animal bodies based on
embryological characteristics, including early
cleavage patterns and the method of coelom
formation.

43. Series Proterostomia (Protostomes)
1. Cleavage or division of the zygote is
spiral and determinate.
2. During development process the mouth
in these animals arises from the blastopore
or from its anterior margin.
3. Coelom or body cavity is formed due to
splitting of mesoderm (schizocoelous).
4. Mesoderm is derived from cells on
anterior lip of blastopore.
5. This series proterostomia includes
animals belonging to phyla aschelminthes
(nematoda) annelida, mollusca and
arthropoda
Series Deuterostomia (Deuterostomes)
1. Cleavage is radial and indeterminate.
2. During embryonic development mouth is
formed at some distance anterior to the
blastopore and blastopore forms the anus.
3. Coelom is developed as an outpouching
of archenterons (enterocoelous).
4. Mesoderm is derived from wall of
developing gut (archenteron).
5. This series includes animals belonging to
phyla echinodermata, hemichordata and
chordata.

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