Ls2 afet unit 4 biodiversity of animals invertebrates
1. UNIT 4: BIODIVERSITY OF
ANIMALS:
INVERTEBRATES
( Campbell and Reece, 2010:
Chapter 32 and 33)
2. Welcome to Your Kingdom
• The animal kingdom extends far beyond
humans and other animals we may
encounter
• 1.3 million living species of animals have
been identified
• Invertebrates (animals that lack a
backbone) account for 95% of known
animal species.
3. EARLY EMBRYONIC
DEVELOPMENT IN ANIMALS
Most animals reproduce sexually, with the
diploid stage usually dominating the life
cycle
After a sperm fertilizes an egg, the zygote
undergoes rapid cell division called
cleavage
Cleavage leads to formation of a blastula
The blastula undergoes gastrulation,
forming a gastrula with different layers of
embryonic tissues.
5. EARLY EMBRYONIC
DEVELOPMENT IN ANIMALS
Fig. 32-2-1
Zygote
Cleavage
Eight-cell stage
Fig. 32-2-2
ygote
Cleavage
Eight-cell stage
Cleavage
Blastula
Cross section
of blastula
Blastocoel
6. EARLY EMBRYONIC
DEVELOPMENT IN ANIMALS
Fig. 32-2-1
Zygote
Cleavage
Eight-cell stage
Fig. 32-2-2
ygote
Cleavage
Eight-cell stage
Cleavage
Blastula
Cross section
of blastula
Blastocoel
Fig. 32-2-3
Zygote
Cleavage
Eight-cell stage
Cleavage
Blastula
Cross section
of blastula
Blastocoel
Gastrulation
Blastopore
Gastrula
Archenteron
Ectoderm
Endoderm
Blastocoel
7. • Many animals have at least one
larval stage.
• A larva is sexually immature and
morphologically distinct from the
adult; it eventually undergoes
metamorphosis.
8. 2. RELATIONSHIP BETWEEN
BODY PLAN AND GROUPING
OF ANIMALS IN PHYLA
• Zoologists sometimes categorize animals
according to a body plan.
• A body plan is a set of morphological
and developmental traits, integrated into
a functional whole living animal.
10. A. SYMMETRY
• Animals can be categorized
according to the symmetry of their
bodies, or lack of it
• Some animals have radial symmetry
• Two-sided symmetry is called
bilateral symmetry
14. C. TISSUES
• Animal body plans also vary
according to the organization of the
animal’s tissues
• Tissues are collections of specialized
cells
• During development, three germ
layers give rise to the tissues and
organs of the animal embryo
15. • Ectoderm is the germ
layer covering the
embryo’s surface
• Endoderm is the
innermost germ layer and
lines the developing
digestive tube, called the
archenteron
• Mesoderm: middle layer
of some body plans
GERM LAYERS ARE:
16. • Diploblastic animals have
ectoderm and endoderm
• Triploblastic animals have an
ectoderm, endoderm and intervening
mesoderm layer.
17. D. BODY CAVITIES
• Most triploblastic animals possess a body
cavity
• A true body cavity is called a coelom and is
derived from mesoderm
• Coelomates are animals that possess a true
coelom
• A pseudocoelom is a body cavity derived from
the mesoderm and endoderm
• Triploblastic animals that possess a
pseudocoelom are called pseudocoelomates
• Triploblastic animals that lack a body cavity are
called acoelomates
18.
19. E. PROTOSTOME AND
DEUTEROSTOME DEVELOPMENT
• Based on early development, many
animals can be categorized as having
protostome development or
deuterostome development
• These two types of developments differ in
regard to:
• Different cleavage
• Different coelom formation
• Fate of the blastopore
20. CLEAVAGE
• In protostome development, cleavage is
spiral and determinate
• In deuterostome development, cleavage
is radial and indeterminate
• With indeterminate cleavage, each cell in
the early stages of cleavage retains the
capacity to develop into a complete
embryo
21.
22. COELOM FORMATION
• In protostome development, the
splitting of solid masses of mesoderm
forms the coelom.
• In deuterostome development, the
mesoderm buds from the wall of the
archenteron to form the coelom.
23.
24. FATE OF THE BLASTOPORE
• The blastopore forms during
gastrulation and connects the
archenteron to the exterior of the
gastrula
• In protostome development, the
blastopore becomes the mouth
• In deuterostome development, the
blastopore becomes the anus
25.
26.
27. 3. SYNOPTIC CLASSIFICATION OF
THE ANIMAL KINGDOM
Kingdom: Animalia
Branch 1: Mesozoa (fish parasites)
Branch 2: Parazoa (cellular)
Phylum: Porifera (sponges)
Branch 3: Eumetazoa (multicellular)
33. Phylum: Porifera (sponges)
• Sedentary animals (fixed in one
position)
• They live in both fresh and marine
waters
• Cellular level of development
• Lack true tissues and organs
• Asymmetrical
34. Phylum:Cnidaria (Hydra, sea anemones)
• True tissue – Eumetazoa
• Both sessile and motile forms including jellies,
corals, and hydras
• Diploblastic body plan
• Radial symmetry
• The basic body plan of a cnidarian is a sac with
a central digestive compartment, the
gastrovascular cavity
• A single opening functions as mouth and anus
35. • Carnivores that use tentacles to capture prey
• The tentacles are armed with cnidocytes,
unique cells that function in defense and
capture of prey
• Nematocysts are specialized organelles
within cnidocytes that eject a stinging thread.
36. Phylum: Platyhelminthes (flat worms)
• Live in marine, freshwater, and damp
terrestrial habitats.
• Triploblastic development
• Acoelomates
• Flattened dorsoventrally and have a
gastrovascular cavity
• Gas exchange takes place across the surface
• Protonephridia regulate the osmotic balance
37. Phylum: Nematoda (round worms)
• Found in most aquatic habitats, in the soil, in
moist tissues of plants, and in body fluids and
tissues of animals
• They have an alimentary canal, but lack a
circulatory system
• Sexual Reproduction
• Internal fertilization
• Some species are parasites of plants and
animals.
39. Phylum: Arthropoda (crabs, insects)
• Found in nearly all habitats of the biosphere
The arthropod body plan consists of a
segmented body,
hard exoskeleton (made of layers of protein
and the polysaccharide chitin
jointed appendages
• The body is completely covered by the cuticle
• When it grows, it molts its exoskeleton.
• Includes: insects, crabs, spiders, millipedes,
centipedes, mites…
41. Phylum: Mollusca (slugs, snails)
• Includes snails and slugs, oysters and clams,
and octopuses and squids
• Most are marine, some inhabit fresh water and
some are terrestrial
• Soft bodied animals, but most are protected by
a hard shell.
42. Phylum: Echinodermata
(sea stars, sea urchins)
• Shared characteristics define deuterostomes
(Chordates and Echinoderms)
–Radial cleavage
–Formation of the mouth at the end of the
embryo opposite the blastopore
• Echinoderms have a unique water vascular
system, a network of hydraulic canals
branching into tube feet that function in
locomotion, feeding, and gas exchange
44. Phylum: Chordata (vertebrates)
• Phylum Chordata consists of two subphyla of
invertebrates as well as hagfishes and
vertebrates
• Vertebrates are a subphylum within the
phylum Chordata
• Chordates are bilaterian animals that belong
to the Deuterostomia.
• All chordates share a set of derived characters
• Some species have some of these traits only
during embryonic development
45. Four key characteristics of
chordates–Notochord
–Dorsal, hollow nerve cord
–Pharyngeal slits or clefts
–Muscular, post-anal tail
