Introduction to the world

of Invertebrates

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Essential Functions for all organisms:

• 1. Respiration

• 2. Feeding/Digestive System

• 3. Response/Nervous System

• 4. Circulatory System

• 5. Reproduction System

• 6. Excretory System

• 7. Movement

These lead to diversity in all living organisms

• The Animal Kingdom is the most diverse kingdom in appearance.

– Each phylum has its own typical body plan / arrangement.

– We will examine the physiology and anatomy of all the Animal Kingdom phyla:

Physiology is the study of the function of the organs

Anatomy is the structure and location of the organs.

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FEEDING:

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-all animals are heterotrophic- must obtain their food from another source.

Types of feeding:

Herbivore:Eats only plants

Carnivores:Eats only animals

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Omnivores:Eats both plants and animals.

Filter Feeders:Do not moveMust filter out food from water

Detritovores:Eat dead and decaying plants and animals

Parasites:Feed off another organism (host) and

harms the host.

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Types of Digestive Systems:

Simplest:Two way digestive systemEnters and exits out the same

opening.

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More complex system:One way digestive systemEnters and exits out different openings.

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Respiratory System:

All animals must:-take in oxygen-give off carbon dioxide

Small and aquatic (water) animals must:

-respire through moist skin-called cutaneous respiration-rely on the process of diffusion

Larger animals:-have various forms of complex modes of respiration

Circulatory System:

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Used to transport items throughout the body.-oxygen-carbon dioxide-food molecules

Small aquatic organisms simply transport items from water into their body by diffusion.

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Two types of circulatory systems:

Open Circulatory Systems -Blood is only partially contained within

a system of blood vessels.-One or more hearts or heartlike organs

pump blood through vessels into surrounding tissues.

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Closed Circulatory Systems

-A heart or heart like organ forces blood through vessels that extend throughout the body. -Closed circulatory systems are characteristic of larger, more active animals.

Excretory System:

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To rid the body of toxic, nitrogenous cellular waste

-main nitrogenous waste is ammonia-ammonia must be eliminated

OR-convert ammonia into a less toxic substance that can then be removed.

Response :

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Receptors used for detecting touch, sound and light.

-utilizes the nervous system

Some organisms have netlike arrangement of nerve nets which consist of individual nerve cells

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Cephalization:

-concentration of sense organs and nerve cells in the front of the body forming a “head region”.

Movement:

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-some animals are sessile- nonmoving

-most are mobile-uses a set of muscles to coordinate the motion.-muscles must be attached to the skeletal system.

Types of skeletal systems:

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Exoskeletons-An external skeleton- is a hard body covering - made up of chitin.

Endoskeleton:

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-Is a structural support located inside the body.

Reproduction:

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-Most animals reproduce sexually-requires what two things?

-sperm -egg

Two types of sexual reproduction:

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1. Internal Fertilization:

2. External Fertilization:

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FISH

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Frogs

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Some simpler animals may reproduce asexually

-one organism divides into 2 new identical organisms.

Hydra and Planarians:

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Some organisms are hermaphrodites.-one organism has both male and female organs and sex cells.

Hermaphrodites:

Trends in animal evolution:• Cell specialization:

– cells, tissues, organs, organ systems

• Early development:– Zygote

• Fertilized egg

– Blastula• A hollow ball of cells

– Blastopore• The blastula folds in creating this opening

– Protostome• Mouth is formed from blastopore

– Deuterosome• Anus is formed from blastopore

– Anus• Opening for solid waste to exit from digestive system

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• Cells of most animal embryos differentiates into three layers called germ layers.

• Ectoderm:– Outermost layer

– Develops into sense organs, nerves, outer skin layer

• Mesoderm:– Middle layer

– Develops into muscles, circulatory system, reproductive system and excretory system

• Endoderm:– Innermost layer

– Develops into digestive and respiratory systems.

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• Cephalization:

– An anterior concentration of sense organs• To have a head region• The more complex the animals become the more

pronounced their cephalization.

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• Segmentation:– “Advanced animals have body segments, and specialization of

tissues.

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