Transcript The Animal Kingdom – Pt-2

Symmetry
 As previously stated sponges are asymetrical – this
means that in whatever plane you cut them their
bodies will NOT be equal
 Jelly fish (Cnidaria) and star fish (Echinoderms)
show radial symmetry (like spokes on a wheel) this
means that you can cut the body in any plane and
have equal sides
 Higher animals show bilateral symmetry 0 this
means that the body can be cut in only one plane
and have equal left and right sides
Animals Can Also Be
Arranged by the
Arrangement of Their
Embryonic Cell Layers
Embryonic (Germinal)
Layers
 Animals whose cells are arranged into two
embryonic layers, an outer ectoderm and an inner
endoderm are called diploblastic
 Often an undifferentiated layer of cells is found
between these two layers and is called the mesoglia
 This type of arrangement is found in cnidarians
Embryonic (Germinal)
Layers
 Animals that have a third embryonic layer located
between the ectoderm and the mesoderm are called
triploblastic
 This layer of tissue is called the mesoderm
 Platyhelminthes to chordates are all triploblastic
What Becomes of these
Layers?
The Endoderm forms the stomach, intestines, lungs,
pancreas, bladder, trachea and thyroid gland
The Mesoderm forms the muscle, cartilage, urinary
tract (not including bladder), heat, spleen, dermis and
notochord
The Ectoderm forms the hiair, nails, lens of the eye,
sweat and sebacious glands, cornea, and the enamel of
the teeth
The Animal Kingdom – Pt-2
Classification and Organization
Dr. Jim Whitfield
Coelom
 The presence or absence of a cavity between the
body wall and the gut wall is very important in
classification
Coelom
 The presence or absence of a cavity between the
body wall and the gut wall is very important in
classification
 The body cavity id called the COELOM
Coelom
 The presence or absence of a cavity between the
body wall and the gut wall is very important in
classification
 The body cavity id called the COELOM
 Animals with a body cavity are called
COELOMATES
Coelom
 The presence or absence of a cavity between the
body wall and the gut wall is very important in
classification
 The body cavity is lined by mesoderm and called
the COELOM
 Animals with a body cavity are called
COELOMATES
 These include annelids, molluscs, arthopods,
echinoderms, and chordates
Coelom
 In some animals the mesoderm is scattered in
pouches throughout the endoderm and ectoderm.
Coelom
 In some animals the mesoderm is scattered in
pouches throughout the endoderm and ectoderm.
 This type of body cavity is called a pseudocoelom
 Animals with this type of body are called
pseudocoelomates
 Examples of this are the Aschelminthes (formally
part of the platyhelminthes)
Coelom
 Animals in which the body cavity is completely
absent are called ACOELOMATES
Coelom
 Animals in which the body cavity is completely
absent are called ACOELOMATES
 Examples are Platyhelminthes
Segmentation
 In some animals such as earthworms the body is
divided both internally and externally into
segments. Many of these segments have repeating
organs this pattern of organization is called
METAMERISM
Notochord
 The notochord is derived from mesoderm. It forms
on the dorsal side of the organism (Back)
 Animals with a notochord are called chordates
Notochord forming in
A chick embryo
SUMMARY OF ORGANIZATION
Phylum - Porifera
 The porifera are marine, asymmetrical animals
commonly known as sponges
Phylum - Porifera
 The porifera are marine, asymmetrical animals
commonly known as sponges
 Sponges have a water transport or canal system.
Water enters through tiny pores called ostia in the
body wall and enter into the spongocoel, or central
cavity, it finally exits though the osculum.
Phylum - Porifera
 The porifera are marine, asymmetrical animals
commonly known as sponges
 Sponges have a water transport or canal system.
Water enters through tiny pores called ostia in the
body wall and enter into the spongocoel, or central
cavity, it finally exits though the osculum.
 This pathway is important in food gathering,
repiratory exchange and removal of waste
Phylum - Porifera
 Choanocytes (Collar cells) are specialized cells which
contain a central flagellum which beats in unison help
move the water and food through the spongocoel
 Digestion is intracellular
 The body is supported by a skeleton made up of spicules
or spongin fibers. These also serve to deter predators
 Spicules are composed of calcium carbonate and spongin
is composed of modified collagen secreted by
sponogcytes
Phylum - Porifera
 Sponges are hermaphrodites – The sexes are not
separate
 Sponges reproduce asexually via fragmentation and
sexually via the formation of gametes (egg and
sperm)
 Fertilization occurs internally
 Sponges have a larval stage morphologically
distinct from the adult stage
Phylum – Cnidaria
Coelenterata
 Cnidarians are aquatic, sessile or free swimming,
radial symmetrical animals
 The name is derived from specialized cells called
cnidocytes which contain stinging capsules called
nematocytes
Phylum – Cnidaria
Coelenterata
 Cnidarians are diploblastic and exhibit tissue level
of organization
 Cnidarians have a central gastro-vascular cavity
with a single opening called a hypostome. The
hypostome is surrounded by tentacles to help bring
in food
 Some cnidarians (corals) have a skeleton composed
of calcium carbonate
Phylum – Cnidaria
Coelenterata
 Cnidarians have two body types called the polyp
and the medusa
The polyp is sessile and the medusa is
free swimming. Cnidarians exhibit
alternation of generations. This means
that the polyps produce the medusa
asexually produce polyps sexually
Phylum – Ctenophora
Coelenterata
 Ctenophora are marine, radial symmetrical
diploblastic organisms exhibiting tissue level of
organization.
 They are often referred to as sea walnuts or comb
jellies
 The body contains external rows of comb plates that
help with locomotion
Phylum – Ctenophora
Coelenterata
 Ctenophora exhibit bioluminescence (the ability to
emit light)
 All reproduction is sexual with external fertilization
Ctenophora
Phylum - Platyhelminthes
 Platyhelminthes or flatworms are bilaterally
symmetrical, triploblastic, acoelomates that exhibit
tissue level of organization
 Most are endoparasites (many found in humans)
 Many use hooks and suckers to absorb nutrients
directly from the host
 Specialized cells called flame cells help with
osmoregulation and excretion
Phylum - Platyhelminthes
 Platyhelminthes are hermaphrodites with internal
fertilization and development
 Many members of the phlya (such as planaria) show
high degrees of regeneration
Tapeworms
Flukes
Planaria
Phylum – Aschelminthes
Nematodes
 Nematodes are roundworms (refers to the shape of
their body in cross section)
 Nematodes may be free living or parasitic, aquatic
or terrestrial
 Nematodes exhibit organ level organization, they
have bilateral symmetry, with a triploblastic body
 They are pseudocoelomates with a complete
digestive tract and a muscular pharynx that pushes
food into the esphagus
Phylum – Aschelminthes
Nematodes
 Waste is removed through excretory pores in the
body
 Sexes are separate (Dioecious) with the females
generally being larger
 Fertilization is internal and development may be
direct or indirect
Phylum – Aschelminthes
Nematodes
 Over 25,000 species have been described
 Examples include: Hookworms, whipworms,
pinworms, dirophilaria (heart worms) and
trichinella
 Trichinella is the worm that causes trichinosis
Phylum - Annelida
 Annelids are fairly complex
 Annelids may be marine or terrestrial, they are
mostly free living (leeches are an exception) They
are triploblastic, coelomates with bilateral
symmetry and and organ level organization.
 There body surfaces are distinctly divided into
segments or metameres
Phylum - Annelida
 Alternating circular and longitudinal muscles help
with locomotion – This is an example of a
hydrostatic skeleton
Phylum - Annelida
 Aquatic annelids have specialized appendages
called parapodia to help with swimming
 Annelids have a closed circulatory system
 Annelids have nephridia. Nephridia come in pairs
and act similarly to the kidney. They are important
in osmoregulation and waste removal
 Annelids have a primitive brain called a ganglia that
attaches to the ventral nerve among other things it
can detect touch and temperature
Phylum - Annelida
 Annelids may be monoecious or dioecious
 Reproduction is sexual