Transcript Group2_Proto_deuterostomesx

GROUP2
PRESENTATION
Question
Discuss the
morphological and
functional
advances of
deuterostomes in
comparison to the
protostomes
Question key words
• Comparison, deutrostomata, protostomata,
morphology and functionality
What are protostomes
• Protostomes[proto-first …stome-mouth] are multicellular organisms
whose mouth develops from a primary embryonic opening; these
encampus the phlyla mollusca, anthropoda and the annelids

Protostomes are the most abundant animals in the
plankton and on the substrates of many marine and
freshwater environments.

They are also available in terrestrial settings
Protosomes are divided into two classes :ecdysozoans
Lophotrochozoans
•
Defined by periodic moulting (absence of ciliated cells) with
a unique pattern of homeobox genes
•
Lophotrochozoans share a different cluster of homeobox
genes and certain similarities in their rRNA genes
What are deuterostomes
• The deutrostomes [deutro-2nd
…stoma…mouth] these are animals whose
mouth develops from a second opening in the
early embryo, opposite to the initial opening
blastopore of the rudimentary gut. Chordates
and echinoderms are deuterostomes
Cleavage
division of cells in the early embryo
• Protostomes exhibit spiral determinate cleavage and
• Spiral cleavage is cleavage in which arrangement of the
blastomeres of each upper tier over the cell junctions
of the next lower tier so that the blastomeres spiral
around the pole to pole axis of the embryo, saying it is
determinate means its fate is guarantee the loss of one
cell in the cleavage simply means the distortion or loss
of a whole tissue in the organism
…Cleavage continued…
• deuterostomes exhibit radial indeterminate cleavage
• Radial cleavage is cleavage in which the spindle axis
are parallel or at right angles to the polar axis of the
oocyte, saying this radial cleavage is indeterminate
simply means the fate of the cell is not certain it can
develop into any tissue part of the organism
Diagrams showing cleavage patterns
Zv
Coelom formation
• Both protostomes and deuterostomes have body cavity
completely lined by mesoderm called a true coelom.
However the coelom develops differently in the two
groups.
• Coelom enables the digestive system and the body wall to
move independently and allows organs to be more
complex.
• In gastrulation the developing digestive tube of an embryo
initially forms as a blind pouch, the archenteron, which has
single opening to the outside known as the blastopore.
Coelom formation
• What is a coelom ; the body cavity in metazoa
located between the intestinal canal and the
body wall
• In deuterostomes the mesoderm forms as
evaginations of the developed gut that pinch off,
forming the coelom. This is called enterocoely
• In protostome a solid mass of the embryonic
mesoderm splits to form a coelom this is called
schizocoely
The formation of the mouth and anus
Circulatory system.
• All deuterostomes have a closed circulatory system except echinoderms.
This prevents blood from being contaminated and subsequently the
blood’s components being destroyed by other factors/chemicals in the
intestinal fluids. This also ensures efficient transportation of blood to all
parts of the body.
• The heart is the pumping organ in most deuterostromes [chordates] for
the efficient supply of blood at a higher pressure.
• In contrast, all protostomes except for the annelids have an open
circulatory system. Their circulatory systems join the coelom and mix with
intestinal fluids. An advantage of having an open circulatory system is
there is enough time for nutrients and oxygen to be absorbed by the cells
Circulatory system cont.
• Some protostomes (annelids) do not have a heart. They use
dorsal vessels to function as a heart. Furthermore these
vessels are linked to the hemocoel instead of capillaries and
venules.
Nervous system.
 Nervous system in the deuterostomes is more advanced. The
central nervous system has a dorsal tubular nerve chord
which is contained in a fluid-filled canal e.g. Branchiostoma .
The brain is well developed in deuterostomes e.g. in
vertebrates except in Echinoderms which have a central
nervous system that gives off radial nerves in each in arm e.g.
sea star. This allows extreme coordination of body organs,
muscles and development of senses e.g. sight.
 Protostomes have rather simple nervous systems with the
exception of some annelids and arthropods. Molluscs e.g.
octopi have a well developed brain but other animals in the
protostome group have ganglia connected by nerve chords.
Locomotion.
• Development of post-anal tail in
deuterostomes e.g in fish it increases
efficiency by the use of fins
• In other vertebrates, the tail is used for
balance’
• Protostomes used longitudinal and/or circular
muscles for movement e.g. earthworms and
some use suckers e.g. leeches.
Skeletal system.
 An endoskeleton is an internal support structure of an animal derived
from the mesoderm.
 The endoskeleton function for support, serves as an attachment site for
muscle thereby providing a means of movement.
 Endoskeleton is chiefly found in the deuterostomes e.g. lizard and it allows
organism to grow .
 An exoskeleton e.g. a shell in snails provides structural support and help
protect the animal. In insects e.g. beetles, the chitinous exoskeleton acts
as a waterproof i.e. prevents water loss.
 In protostomes and deuterostomes, the exoskeleton limits growth and it
is heavy e.g. in sea stars.
 The annelids and nematodes have a hydrostatic skeleton and the fluid
allows organism to change shape and to produce movement
Excretion.
•Protostomes excrete through simple cells ( tubules/canals ) e.g.
in earthworms.
•In other phyla, coelom acts the fluid for waste transportation
by accumulation of wastes.
• The Malpighian tubules of insects, and some other
arthropods move solutes and nitrogenous wastes from the
body’s fluid.
•Unlike protostomes, deuterostomes have more complicated
excretory systems, with the exception of Echinoderms which
lack waste disposal organs, and were waste diffuses from
respiratory surfaces. E.g. in starfish, waste is removed by tube
feet and papulae through diffusion.
Excretion cont.
•While lack of specialized excretory organs exist in
protostomes, some animals in the deuterostomata have also
this feature and these include the Ciona intestanilis ( Chordata
sub-phylum Urochorata) which have no kidneys at all and
excretion is through nephrocytes.
• The other deuterostomes have kidneys and these have made
this group more successful than the protostomes e.g. crocodile
(phylum Chordata)
Figure 1: Diagram showing excretory organs of an earthworm (Annelid;protostome) , Starfish (Echinoderm; deuterostome), lizard (Chordate;deuterostome)
Summary of Deutrosomes vs.
protosomes
the main difference between
protosomes and Deutrosomes is
how they develop in the early
embryonic stages
Protosomes
Deutrosomes
 Cleavage or division of the zygote is
spiral and determinate.
 Cleavage is radial and intermediate.
 During development process the
mouth in these animals arises from
the blastopore or from its anterior
margin.
 During embryonic development mouth
is formed at some distance anterior to
the blastopore and blastopore anus.
• Coelom or body cavity is formed
due to splitting of mesoderm
SERIES PROTEROSTOMIA
(PROTOSTOMES)
 Coelom is developed as an out
pouching of archenterons.
SERIES DEUTEROSTOMIA
(DEUTEROSTOMES)
 Mesoderm is derived from cells on
anterior lip of blastopore
 Mesoderm is derived from wall of
developing gut
 Lophophores belong to this group
 Chordates belong to this group
 This series includes animals belonging  This series includes animals belonging
to phyla aschelminthes (nematode)
to phyla Echinodermata. Hemichordate
annelida, mollusca, and arthropoda.
and chordate.
Thank you so much for your time!!!
2 Mapindu Munyaradzi
3 Mushove Donald
4 Chigiya William
5 Chingosho Praise
6 Moyo Desire
7 Matombo Tinotenda
8 Shiniwa Munyaradzi
9 Mabauwa Alwyu
10 Ndlovu Melissa
11 Chikaka Munashe
12 Magunda Ruramai
13 Marufu Tafadzwa
14 Marikanda Sohn
15 Bukuta Tatenda
16 Phalen Chiomba
17 Joy Chipidza
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FROM THE ABOVE GROUP MEMBERS