Intro to Animals
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Transcript Intro to Animals
Intro to Zoology
What is an animal?
Typical Characteristics:
1) Eukaryotic –each cell has a nucleus
2) Multicellular-Made up of many cells
Cells>Tissue>Organs>Organ Systems
3) Heterotrophic- must eat food to get energy and
nutrients- through ingestion and digestion
4) Do not have cell walls
5) Can Move (some are sessile, which means that they
don’t move) EX: sponges and barnacles
Origins of animals :
Most likely evolved from colonial
protists
Believed to have developed in
the water
Phylums
Porifera
Cnidaria
Platyhelminthes
Nematoda
Annelida
Mollusca
Arthropoda
Chordata
***There are
more than 9
phylums but
these
represent the
most
commonly
seen
animals.
Match the name of phylum with a picture of a member!
http://www.biologycorner.com/resources/animal_phylu
m_chart.gif
Reproduction and
Development
Most animals reproduce sexually.
Some can reproduce asexually.
Fertilization occurs when a sperm penetrates an egg to
form a single cell called a zygote.
This may be external (outside male and female) EX:
Fish or internal ( inside the female) EX: Horse
Cell Division
Zygote begins dividing by mitosis to form two new cells.
Each new cell will continue to divide over and over
again until a hollow ball called a blastula is formed.
One side of the blastula begins to fold inward, making
an inner pouch. At this point, the embryo is called a
gastrula.
Germ Layer Development
The layers that form will eventually form the tissue and
organs of the animal. Most animals possess three
layers of tissue (sometimes called germ layers):
1) Ectoderm: outermost layer of cells; eventually forms
the outer covering (skin) and nervous system.
2) Mesoderm: middle layer of cells; eventually forms
the skeleton, muscles, and circulatory system
3) Endoderm: Inner layer of cells; becomes the
digestive tract, internal organs, and respiratory tract
Body Cavities
As the layers of tissue form organs and organ systems,
some organisms develop a fluid filled space that forms
between the digestive tract and the outer wall of the
body during development.
Not found in simple animals
May aid in movement
Fluid may act as a reservoir for nutrients and wastes,
which diffuse into and out of the animal’s body
Types of Body Cavities
Acoelomates: 3 layers of tissue, but no body cavity is
present ( Gut)
Pseudocoelomates- 3 Layers of tissue and a modified
body cavity present ( not lined with mesoderm)
Coelomates- a true body cavity present (lined with
mesoderm)
http://pulpbits.com/wp-content/uploads/2013/12/threefunctions-of-a-body-cavity.jpg
Patterns of Symmetry
Asymmetrical – an irregular shape. Some simple
animals do not display symmetry (EX: Sponges)
Radial- Similar parts branch out in all directions from a
central line ( like spokes on a bicycle tire)
Bilateral- two halves on either side of a central plane
are similar
A. Usually exhibit cephalization –concentration of
sensory structures in the anterior (head) end of the
animal.
Bilateral Symmetry words
Terms used to describe location of certain structures
and organs on an animal:
Anterior: head end
Posterior: Tail end
Dorsal: Back
Ventral: Front
http://www.dogsindepth.com/hound_dog_breeds/image
s/greyhound_h05.jpg
Segmentation
A body composed of repeating similar units
In some phyla, segments may look different and have
different functions.
Support and Protection of
Body
Hydrostatic skeleton- body is supported by the
pressure of their fluid filled bodies (EX: jellyfish)
Exoskeleton- A rigid outer covering that protects the
soft tissue of many animals ( includes many
invertebrates such as crabs and beetles)
Endoskeleton- an internal skeleton that can support a
large, heavy body
Vertebrate VS. Invertebrate
Most animals that exist today are classified as
invertebrates; animals that lack a backbone
EX: insects, sponges, starfish, jellyfish, clams, worms,
etc.
Humans are a type of chordate called a vertebrate, an
animal with a backbone.
Chordata is the only phylum that contains vertebrates
(although not all chordates are vertebrates)
Digestive System
In Sponges, digestion occurs within individual cells
(intracellular)
Gastrovascular Cavity- A digestive chamber with a
single opening (incomplete digestive system) Ex:
jellyfish and flatworms
Digestive tract (or gut) runs from the mouth to the
posterior end or anus. EX: humans, earthworms, and
spiders
Respiratory System
Gas Exchange: the process of exchanging carbon
dioxide (in the blood) with oxygen (in the environment)
Gills: Organs that are specialized for gas exchange in
water
Lungs: Organs for gas exchange, which are composed
of moist, membranous surfaces deep inside the
animal’s body
Circulatory System
Moves blood or a similar fluid through the body to
transport oxygen and nutrients to the cells.
Open circulatory system- blood like circulatory fluid is
pumped from vessels in the body into the body cavity (
it bathes the organs) then is returned to the vessels.
Closed circulatory system- blood circulates through
the body in tubular vessels.