Download Animals in a `nutshell` #1 - Phillips Scientific Methods

What are Animals?
General Characteristics:
1) multicellular, ingestive heterotrophic
eukaryotes
2) animal cells lack cell walls
3) unique tissues: nervous and muscle
4) Most reproduce sexually
5) Diploid is dominant phase of life
cycle
Early Embryonic Development
Zygote
Cleavage
Blastula
Gastrulation
Gastrula
Some organisms develop directly into some form
of a miniature adult, but many organisms go
through a larval stage.
Typically, after the larval stage, metamorphosis
occurs, which is a resurgence of development that
transforms the animal into an adult.
Insect metamorphosis
Bilateral symmetry: animal can be divided
Into mirror images
Radial symmetry:
Anterior
Animal can be divided
Posterior
Into equal halves through
Dorsal
a central axis
Ventral
Body Plans
Gastrovascular cavity: cnidaria
Acoelomate: flatworms have no internal
cavity
Pseduocoelomate: roundworms have
internal cavity in contact with endoderm
Coelomate: other animals have an
internal space completely lined by
mesoderm
Acoelomate – no body cavity
Pseudocoelomate –
Cavity not completely
lined with mesoderm
Coelomate –
Cavity completely lined
with mesoderm
Phylum Chordata:
Subphylum: Urochordata: sea squirts and
tunicates
Cephalochordata: amphioxus
Vertebrata: lampreys, sharks, fish,
amphibians, reptiles, birds, and mammals
Phylum Chordata
Characteristics
1) a notochord
2) a dorsal, hollow nerve cord
3) pharyngeal gill slits
4) muscular postanal tail
4 characteristics of Chordates
Urochordata and Cephalochordata
are invertebrate chordates
Vertebrates characteristics
1) highly cephalized
2) well developed sense organs and brain
3) a vertebral column
4) a closed circulatory system
5) endoskeleton
6) usually paired appendages
7) separate sexes
Superclass Agnatha: The jawless vertebrates
Jawless, cartilaginous, lack
paired appendages,
gills, notochord
Lampreys
and
hagfish
Two important adaptations furthered the
diversity and resources used by vertebrates
1) Jaws
2) Two Paired appendages
Jaws evolved from pharyngeal gill slits
Example of modern jawed, paired appendage, no lung organism
Class Chondrichthyes
Cartilaginous
endoskeleton
gills
Internal
Fertilization
Sharks, skates, and rays
Bony Fishes (class Osteichthyes) – Swim Bladder: an air sac that
helps control buoyancy in fish
Bony skeleton and jaws
External Fertilization
Gills
Swim Bladder
Overview of
Chordate Phylogeny
Next Big
Innovation:
Legs
First vertebrates on land were Amphibians:
Examples of Amphibians
Amphibians
Lungs and skin serve as respiratory
organs
Skin is smooth and moist
Metamorphosis found in some species
External fertilization and external
development
Overview of
Chordate Phylogeny
Next Big
Innovation:
Amniotic Egg
The Amniotic Egg allowed vertebrates to
further explore terrestrial habitats
Why?
The Amniotic Egg allowed vertebrates to
further explore terrestrial habitats
because it allowed embryonic
development to be completed
in the absence of water – thus
enabling complete terrestrialism
Amniotic egg – provides nutrients and protection
Modern Reptiles
Reptiles
Scales, help prevent dehydration
Well-developed lungs
Ectothermic
Amniote egg
Internal fertilization
Most external development
Endotherm –
Uses metabolic Energy to
Regulate Body temp
Ectotherms
- uses Environmental Energy to
Regulate body temperature
Flight adaptations:
Aves
Feathers
Scales on legs
Adaptive to flight
Bones are light
Toothless but have beak
Gizzard
Lungs and 4 chambered heart
Endothermic
Internal fertilization, external development in
amniote egg
Overview of
Chordate Phylogeny
Mammals and
Hair
3 major groups of mammals:
1) Monotremes – egg-laying mammals
2) Marsupials – pouched mammals
3) Eutherians – placental mammals
Phylogeny of Mammals
Evolved to fill
similar niches
Mammals
Mammary glands
Long duration of parental care
Hair
Diaphragm
Differentiation of teeth, shearing,
grinding, or crushing
Excellent sensory system
Primates
Primates
Opposable thumb
Brachiation
Larger brain capacity
Care of young