Animal: Introduction
Animals are multicellular, aerobic
heterotrophs that reproduce sexually and
some asexually
Outline
Key concepts
Several characteristics of animals
Some terms
Classification of Animal kingdom
Major animal groups
Key Terms
Conclusions
Key Concepts:
All animals are multicelled heterotrophs
Animals reproduce sexually or asexually
Animals originated about 1.2 million years ago
Comparisons of body plans of existing animals
with fossils reveal that there were several trends
in the evolutions of certain lineages
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Key Concepts:
The
sponges are structurally simple animals
without body symmetry
Cnidarians
have radial symmetry
Bilateral
symmetry is seen in animals more
complex than the cnidarians and have
developed organ systems
Several characteristics of animals
Animals
– Multicellular Eukaryotes
– Their cells lack cell walls
– Heterotrophs - That ingest their food
– Aerobic respiration - Oxygen
– Most animals reproduce sexually - With the
diploid stage usually dominating the life cycle
– Motile - life cycle
– Nervous tissue and muscle tissue - unique to
animals
Some terms
The entire structure of an animal, its organ
systems, and the integrated functioning of its
parts are known as its body plan.
Protostomes and deuterostomes differ in
the fate of the blastopore , the opening of
the cavity that forms in the spherical
embryo.
In the protostomes, the mouth arises from
the blastopore.
In the deuterostomes, the blastopore gives
rise to the anus.
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Body Plans: Basic Structural Designs
Overall shape is referred to as symmetry. A
symmetrical animal can be divided into similar halves
along at least one plane.
Animals that have no plane of symmetry are said to be
asymmetrical.
An organism with radial symmetry has one main axis
around which its body parts are arranged.
Bilaterally symmetric animals can be divided into
mirror images by a single plane.
Examples of Body Symmetry
1. Radial
Live in water
2. Bilateral
Mirror image
Bilaterally symmetrical
animals have
– A dorsal (top) side and a
ventral (bottom) side
– A right and left side
– Anterior (head) and
posterior (tail) ends
– Cephalization, the
development of a head
Ne matoda
Rotifera
Ne mertea
Annelida
Arthropoda
Mollusca
Chordata
Deuterostomia
Platyhelminthes
Brachiopoda
Echinodermata
Phoronida
“Radiata”
Ectoprocta
Cnidaria
Ctenophora
Evolutionary Relationships Among
Major Groups of Animals
Porifera
Protostomia
Bilateria
Eumetazoa
Metazoa
Ancestral colonial
flagellate
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Major Animal Groups
Some
Representatives
Group
Poriferans
Cnidarians
Flatworms
Existing
Species
Sponges
Hydras, jellyfishes
Turbellarians, flukes, tapeworms
8,000
11,000
15,000
Annelids
Leeches, earthworms, polychaetes
15,000
Mollusks
Snails, slugs, squids, octopuses
110,000
Arthropods
Crustaceans, spiders, insects
1,000,000+
Roundworms
Pinworms
20,000
Echinoderms
Sea stars, sea urchins, sea cucumbers
6,000
Chordates
Invertebrate chordates:
Tunicates, lancelets
Vertebrate chordates:
Jawless fishes
Jawed fishes
Amphibians
Reptiles
Birds
Mammals
84
21,000
4,900
7,000
8,600
4,500
2,100
Ingestion
Bilateral symmetry
Asymmetry
Deuterostomes
Radial symmetry
Protostomes
Body plan
Dosal
Ventral
In Conclusion
Animals
are multicellular, aerobic
heterotrophs that reproduce sexually and
some asexually
They
have tissues, organs, and organ systems
Animals
range from simple sponges to
vertebrates
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In Conclusion
The sponge body is asymmetry
Cnidarians have radial symmetry and have tissue
level organization
Almost all animals above cnidarians show bilateral
symmetry, form tissues, organs and organ system
Two major lineages diverged shortly after flatworms
evolved: Protostomes and Deuterostomes
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