Animal Diversity - Jeppe High School for Girls · ANIMAL DIVERSITY Important features of body...

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ANIMAL DIVERSITY Important features of body plans: 1. SYMMETRY & CEPHALISATION: Asymmetry Radial symmetry Bilateral symmetry No symmetry in the body shape Body parts are arranged around a central axis Body parts are arranged on either side of a central axis No pattern to body parts, are irregular Mirror images will be seen along a number of planes if sliced longitudinally Can be cut in two mirror images in one plane only Cannot be divided into halves that are mirror images Radial animals have no front or back end They have a front and back end, and a definite dorsal and ventral surface Advantages: Food and oxygen can be absorbed through the whole body Advantages: The body can obtain food from all directions Stimuli can be observed in all directions for protection and catching of prey Advantages: Cephalisation causes the sensory organs to be concentrated in the front of the body Movement is very fast and effective Disadvantages: Animals are often sessile (stays in one place) Movement is absent or ineffective Cephalisation does not occur Disadvantages: Movement is slow and ineffective No concentrated nervous system Cephalisation does not occur Disadvantages: Due to cephalisation the organisms may have blind spots (cannot see behind themselves)

Transcript of Animal Diversity - Jeppe High School for Girls · ANIMAL DIVERSITY Important features of body...

Page 1: Animal Diversity - Jeppe High School for Girls · ANIMAL DIVERSITY Important features of body plans: 1. SYMMETRY & CEPHALISATION: Asymmetry Radial symmetry Bilateral symmetry No symmetry

ANIMAL DIVERSITY

Important features of body plans:

1. SYMMETRY & CEPHALISATION:

Asymmetry Radial symmetry Bilateral symmetry

No symmetry in the body

shape

Body parts are arranged

around a central axis

Body parts are arranged

on either side of a central

axis

No pattern to body parts,

are irregular

Mirror images will be seen

along a number of planes if

sliced longitudinally

Can be cut in two mirror

images in one plane only

Cannot be divided into

halves that are mirror

images

Radial animals have no

front or back end

They have a front and

back end, and a definite

dorsal and ventral surface

Advantages:

Food and oxygen can be

absorbed through the

whole body

Advantages:

The body can obtain food

from all directions

Stimuli can be observed in

all directions for

protection and catching of

prey

Advantages:

Cephalisation causes the

sensory organs to be

concentrated in the front

of the body

Movement is very fast and

effective

Disadvantages:

Animals are often sessile

(stays in one place)

Movement is absent or

ineffective

Cephalisation does not

occur

Disadvantages:

Movement is slow and

ineffective

No concentrated nervous

system

Cephalisation does not

occur

Disadvantages:

Due to cephalisation the

organisms may have blind

spots (cannot see behind

themselves)

Page 2: Animal Diversity - Jeppe High School for Girls · ANIMAL DIVERSITY Important features of body plans: 1. SYMMETRY & CEPHALISATION: Asymmetry Radial symmetry Bilateral symmetry No symmetry

2. EMBRYONIC TISSUE LAYERS:

Embryos develop layers of cells called germ layers. Germ layers give rise to specific

tissues and organs to make up a fully developed animals body. There are three germ

layers:

• Ectoderm – outer layer that forms the skin

• Endoderm – inner layer which lines the gut

• Mesoderm – middle layer that gives rise to internal organs

Diploblastic animals Triploblastic animals

Organisms have cells arranged in two

layers

Organisms have their cells arranged in

three layers

Ectoderm and endoderm Ectoderm, endoderm and mesoderm

Do not form tissues and organs – cellular

level of organisation

Allows an increase in complexity

3. DEVELOPMENT OF A COELOM:

Coelom – a fluid filled cavity that develops in the mesoderm

Provides a cavity for the development of internal organs and separates the digestive

canal from the body wall to allow it to function apart from each other. The liquid inside

the coelom acts as a shock absorber to protect the internal organs, and also acts as a

hydrostatic skeleton to allow muscle movement. It also allows materials to diffuse

rapidly through the fluid in the coelom to the body cells.

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Acoelomate Coelomate

No coelom is present in the mesoderm A coelom (body cavity) is present in the

mesoderm (surrounded by the mesoderm

Pseudocoelomate

The coelom is only surrounded on one side

by the mesoderm

4. NUMBER OF GUT OPENINGS:

Blind gut – having only one body opening through which ingestion (eating) as well as

egestion (defecation) takes place.

Page 4: Animal Diversity - Jeppe High School for Girls · ANIMAL DIVERSITY Important features of body plans: 1. SYMMETRY & CEPHALISATION: Asymmetry Radial symmetry Bilateral symmetry No symmetry

Disadvantages of a blind gut:

• The animal cannot ingest and egest at the same time

• The ingestion, digestion and egestion are not systematic

• There is a mixing of digested and undigested food

• Digested food is also expelled during egestion

Through gut – having two body openings, a mouth at one end and an anus/cloaca (common

opening for the digestive system and the reproductive system) at the other end.

Advantages of a through gut:

• Allows specialisation – mouth ingests food; stomach and intestines digest food;

intestines absorb food; anus egests undigested food

• Ingestion, digestion and egestion are systematic processes

• There is no mixing of digested and undigested food

Page 5: Animal Diversity - Jeppe High School for Girls · ANIMAL DIVERSITY Important features of body plans: 1. SYMMETRY & CEPHALISATION: Asymmetry Radial symmetry Bilateral symmetry No symmetry

Phylum Porifera Cnidaria Platyhelminthes

Symmetry

Cephalisation

Tissue layers

Coelom

Blood system

Gut

Other

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Phylum Annelida Arthropoda Chordata

Symmetry

Cephalisation

Tissue layers

Coelom

Blood system

Gut

Other

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CHARACTERISTICS OF CHORDATES:

The chordates are an extremely successful group of animals and they occupy a wide

range of habitats. They are all very similar in form. The following distinctive features

(some only present in embryos) distinguish Phylum Chordata from other animals. They

all have a:

• Notochord – a rod-like support that may persist throughout life but in most

cases, it is replaced by a vertebral column

• Hollow, dorsal, tubular nerve chord – persists throughout life in most

chordates and usually forms a brain at its anterior end

• Pharyngeal (gill) slits – appear during development of all chordates but in

terrestrial forms they disappear in adult animals

• Post-anal tail – body extends past the anal opening

• Blood circulating – from main ventral vessel and back through the body in a

dorsal vessel

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CHARACTERISTICS OF SUB-PHYLUM VERTEBRATA:

Chordates that have vertebrae, including fish, amphibians, reptiles, birds and

mammals – all the animals we are familiar with. They all have:

• An endoskeleton of cartilage and/or bone

• A notochord that, during embryonic development, becomes incorporated into

the vertebral column that is made up of cartilaginous or bony vertebrae

• Two pairs of appendages (fins or limbs) attached to girdles

• Extracellular (outside the cells) digestion in a complex digestive tract

• A closed circulatory system

• They may be ectotherms or endotherms

ROLE OF INVERTEBRATES IN AGRICULTURE & ECOSYSTEMS:

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