Classification of Animals According to Backbone Structure 1

Classification of Animals According to Backbone Structure 1

A.  Invertebrates

More than 95 percent of the earth's animal species are invertebrates. These are animals without backbones. They are found in almost every habitat — from forest to grasslands, from oceans to ponds, from deserts to a garden.

The following are types of invertebrates:

1.    Poriferans

Porifera means "pore bearer." Sponges represent the animals belonging to this group. There are about 5,000 species of sponges. Sponges do not have heads, arms or internal organs. Their size ranges from 2.5 centimeters to more than 1.2 meters long. They are the sources of scrubbing pads.

2.    Worms

Worms are of three types. The segmented worms are called the                 

annelids. The unsegmented worms are the round worms or nematodes and the flatworms.

a.   Nematodes or Round Worms

These are examples of unsegmented worms. Their bodies are round, slender and usually pointed at the ends. Examples of this type are the asca^is, hookworm, pinworms.

b.   Annelids or Segmented Worms

Earthworm and leeches are examples of annelids. Earthworms eat decaying plant matter,.whereas leeches suck the blood of fish and other water creatures.

c.   Flafworms

Most flatworms measure less than 2.5 centimeters long. Tapeworms, the largest flatworms, grow up to 30 meters long. Almost all flatworms are hermaphrodite — they have both male and female reproductive organs.

3.     Coelenterates

Jellyfish, sea anemones and corals are examples of coelenterates. Most                      

coelenterates are marine. They are also carnivorous but do not chase prey.                

They trap food organisms that accidentally come in contact with their stinging cells.

4.    Molusks

Most mollusks have hard shells enclosing a soft body. They have a skin like organ called a mantle. Mantle is a fleshy extension of the body wall that secretes liquid shell materials. Snail, slugs, oysters, clams, squids and octopus are examples of mollusks.

5.    Echinoderms

Echinoderms are slow-moving. They have spiny skins. They have tube-feet which are tubelike structures that protect from the body in rows. The tube feet is used for moving, feeding and breathing.

Starfish, sea urchins, sea lilies and sea cucumbers are examples of animals belonging to the Phylum Echinodermata.         

6.    Arthropods

All arthropods have jointed limbs and segmented bodies. These bodies are covered by an exoskeleton or outside shell. The exoskeleton contains chifin, a stiff horny material that act as framework.

Spiders, insects, cockroaches, beetles, flies and butterflies are some examples of arthropods belonging to the Phylum Arthropoda.

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tyyy 6 years ago

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