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

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Origins of animals :



Most likely evolved from colonial protists

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Believed to have developed in the water

 Porifera  Cnidaria  Platyhelminthes  Nematoda  Annelida  Mollusca  Arthropoda  Chordata

Phylums

***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/three functions-of-a-body-cavity.jpg

Patterns of Symmetry

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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

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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

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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.