Transcript Classification and Introduction to Animals Chapter 18 & 34

CHARACTERISTICS
OF ANIMALS:
WELCOME TO YOUR
KINGDOM!
Adapted from Kim Foglia - April 2015
ANIMALS
Invertebrates
(animals without a backbone)
Porifera
Cnidaria
Worms
Mollusks
Echinoderms
Arthropods
ANIMALS
Vertebrates
(animals with backbones)
Fish
Amphibians
Reptiles
Birds
Mammals
CHARACTERISITCS OF ALL ANIMALS:
1.
2.
3.
4.
5.
Eukaryotic
Heterotrophic (ingestive)
Multicellular/differentiated cells
Cells have NO cell walls
Movement (at some point in
lifespan)
6. Reproduction (Most sexual)
ANIMAL EVOLUTION
Cnidaria
Porifera
sponges
jellyfish
Nematoda
Platyhelminthes
Annelida
Mollusca
Echinoderm
Arthropoda
flatworms roundworms mollusks segmented
worms
insects
spiders
Chordata
starfish
vertebrates
backbone
segmentation
endoskeleton
eucoelom
body cavity
bilateral symmetry
tissues
multicellularity
Ancestral Protist
LIFE ON EARTH
EMBRYOLOGY
REPRODUCTION
•Most animals reproduce sexually
•Diploid stage usually dominates life cycle
•Haploid stage characterized by sperm and
eggs produced by meiotic division
•In most animal species, a small flagellated
sperm fertilizes a larger non-motile egg,
forming a zygote
DEVELOPMENT
•The zygote then undergoes cleavage, a
succession of mitotic cell divisions with no
cell growth between divisions
•Cleavage leads to a multicellular (usually
hollow) ball called a blastula
•Blastula goes through gastrulation – the
layers of embryonic tissues that will
become adult parts are produced
•Result is a gastrula
•Some animals, including humans, develop
directly into adults
•Most animals include a larval stage
•Larva – sexually immature form of the
animal that is:
morphologically different from adult
Eats different food
Often has a different habitat
•Larvae go through metamorphosis to
juvenile stage that resembles adult
EMBRYONIC DEVELOPMENT
HISTORY OF ANIMALS SPANS MORE
THAN ½ BILLION YEARS
• The animal kingdom includes the
greatest diversity of living organisms
• Has an even greater diversity of extinct
ones; ~99% of all species that have ever
lived are now extinct
• Scientists estimate that the common
ancestor of living animals lived sometime
between 800 and 675 mya
ANIMALS CAN BE CHARACTERIZED BY
BODY PLANS
•Despite the diversity in morphology,
animals share a relatively small number of
“body plans”
•Body plan – particular set of
morphological and developmental traits,
integrated into a functional “whole”
SYMMETRY
•A basic feature of animals is their type of
symmetry – lack of it
•Asymmetrical (sponges)
•Radial symmetry: revolves around an axis
(sea anemone)
•Bilateral symmetry: two-sided; has 2 axes
of orientation, front to back and top to
bottom (crawfish)
KINDS OF SYMMETRY
Asymmetrical
Radial
Bilateral
DORSAL
POSTERIOR
ANTERIOR
VENTRAL
CEPHALIZATION
•Most animals with bilateral symmetry
have sensory equipment located at the
anterior end, including a central nervous
system (brain) in the head
•Provides efficient response to stimuli as
sense organs encounter stimulus before
rest of organism
TISSUE DEVELOPMENT
•In animals, true tissues are collections of
specialized cells isolated from other
tissues by membranous layers
•Sponges and a few others lack true
tissues
•Gastrulation develops these layers – called
germ layers
GERM LAYERS
•Ectoderm: covers surface of embryo;
gives rise to outer covering on animal (and
sometimes to central nervous system)
•Endoderm: innermost germ layer; lines the
pouch that forms during gastrulation;
gives rise to lining of digestive tract and
organs such as liver or lungs
•Animals that have only these two layers
are diploblastic
•Examples: sponges, jellyfish, anemones
TRIPOBLASTIC ANIMALS
•Most animals have a middle germ layer
called the mesoderm which fills much of
the space between the ectoderm and the
endoderm
•Forms muscles and most other organs
between digestive tract and outer
covering of animal
BODY CAVITIES
•Most tripoblastic animals have a body
cavity – a fluid or air filled space between
digestive tract and outer body wall
•This cavity is called a coelom
•A “true” coelom forms from tissues from
the mesoderm
•Coelomates – organisms with a true
coelom
•Pseudocoelomates –
coelom formed
from mesoderm and
endoderm; also a
fully functional
body cavity
•Acoelomates – lack
a body cavity
PROTOSTOME & DEUTEROSTOME
DEVELOPMENT
PROTOSTOMES
DEUTEROSTOMES
• Fate of embryonic cells
determined very early in
development
(DETERMINATE)
• SPIRAL cleavage
• Blastopore becomes
MOUTH
• INVERTEBRATES
except ECHINODERMS
• Fate of embryonic cells
determined later in
development
(INDETERMINATE)
• RADIAL cleavage
• Blastopore becomes
ANUS
• ALL VERTEBRATES
(Fish, amphibians, birds,
reptiles, mammals)
plus ECHINODERMS
“Exception to the rule”
ECHINODERMS ARE
THE ONLY
INVERTEBRATE
DEUTEROSTOMES