A Very Diverse Kingdom

Kingdom Animalia Characteristics

All animals share the following characteristics

1.Eukaryotic2.Multicellular3.Reproduce sexually4.Heterotrophic5.Motile, at least for part of their

life

Animals are taxonomically grouped based on three main features:

Number of body layers Type of Body cavity Body Symmetry

Kingdom Animalia Features

The 3 main layers appear very early in embryonic development. In humans the layers are:

Ectoderm – skin, nerves Mesoderm – muscles, blood,

kidneys Endoderm – lungs, liver, gut

lining

Feature 1: Number of body layers

The two main types of body cavities are:

Coelomates –have a fluid filled body cavity that supports organ systems

Acoelomates – lack a fluid filled body cavity like flatworms

Feature 2: Type of Body Cavity

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The three main types of symmetry are:

Bilateral – can be cut into two mirror images through a central line.

Radial – body is organized around a central axis. They are symmetrical around any central cut.

Asymmetry – no distinctive symmetry

Feature 3: Body Symmetry

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Top

Bottom

Back

Front

Animal Phyla

Animalia phyla are spilt into two major groups based on the presence or absence of a spinal cord and vertebra

1.Non-chordates or invertebrates

2.Chordates or vertebrates

These are animals without a notochord (backbone)

There are eight phyla of invertebrates1. Porifera, Sponges2. Cnidarians, jellyfish3. Platyhelminthes, Flatworms 4. Annelids, segemented worms

pinworm5. Nematoda, Roundworms6. Mollusca, snails, clams7. Echinoderms, starfish8. Arthropods, insects, crabs

spiders

Invertebrate Phyla

1. Porifera: Sponges lack any definite symmetry Sponges are the simplest

animals, lack defined tissues and organs

Are hermaphroditic Fertilized eggs become free-

swimming larvae, which then attach to the ocean floor, metamorphose and become fixed in one place.

2. Cnidarians: Jellyfish and Corals

Have radial symmetry

reproduce both sexual and asexually

Have tentacles with stinging cells that they use to capture food.

3. Platyhelminthes: Flatworms

Have bilateral symmetry.

Free living worms are hermaphroditic, they generate a reproductive system only during breeding season.

Can be free-living or parasites.

4. Nematodes: Roundworms

Have bilateral symmetry.

Have long thin, round worm like bodies

Most are free-living, however some are parasitic and can cause major health concerns.

Simplest organisms to have a complete digestive tract.

5. Annelida: Segmented Worms

Have bilateral symmetry

Have round, segmented bodies which is beneficial for movement, can move different parts at a time, increases flexibility.

Have a coelom

6. Mollusca: Snails, Clams, Squid

Have bilateral symmetry

Are coelomicThey are soft-

bodied animals. Most cover their body with a shell for protection.

Have radial symmetryHave spiny outer

covering for protectionMove by changing water

pressure inside tubes in the arms

Can be stationary or burrowing

Have a coelom

7. Echinodermata: Starfish

Have bilateral symmetry. Ecologically important part of food

chains due to their abundant numbers

Have a coelom, including simple respiratory, circulatory and excretory systems

There are four group of arthropods:1. Arachnids (spiders)2. Centipedes & Millipedes3. Crustaceans (crabs, shrimp)4. Insects

8. Arthropoda: Insects and Spiders

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