The animals which lack the backbone or vertebral column are called invertebrates.
With 2 million known species on earth, about 97% of the animals are invertebrates.
Many invertebrate animals have soft body while some arthropods and molluscs have hard exoskeleton for supporting and protecting their body.
Spongilla, Jellyfish, Tapeworm, Roundworm, Earthworm, Leech, Prawn, Butterfly, Spider, and Millipede, etc are examples of invertebrate animals.
The invertebrate animals ha eight phyla category.
1. Phylum: Porifera
The term Porifera means pore bearer animals.
The members of this phylum are called the first multicellular animals and are commonly called sponges.
Sycon and sapodilla etc are the examples of this phylum.
2. Phylum: Coelenterata
The term Coelenterata means a group of animals whose body has a central cavity called coelenterata.
Most of the animals of this phylum are marine except hydra.
Hydra, jellyfish, coral and obelia etc are the examples of this phylum.
3. Phylum: Platyhelminthes
The phylum Platyhelminthes includes animals with a flat and soft body.
We identify this type of phylum animals as flatworms.
Liver fluke, tapeworm, blood fluke and planaria etc are the examples of this phylum.
4. Phylum: Nemathelminthes
The term Nemathelminthes means threadworms.
We also call it roundworm.
Ascaris, hookworm and pinworm etc are the examples of this phylum.
5. Phylum: Annelida
The term Annelida means the animals having a ring-like body.
The animals of this phylum are commonly known as segmented worms.
Earthworm, leech, and sandworm etc are the examples of this phylum.
6. Phylum: Arthropoda
The term Arthropoda means animals with jointed feet or appendages.
The phylum Arthropoda is the largest animal phyla because they are a presence in all habitat like air, water and land too.
Crab, grasshopper, housefly, scorpion, centipede and bee etc are the examples of this phylum.
7. Phylum: Mollusca
The term Mollusca means animals with a soft body.
It is the second-largest phylum in a number of species.
Octopus, snail, cuttlefish, slug, chiton and unio etc are the examples of this phylum.
8. Phylum: Echinodermata
The Echinodermata includes spiny skinned animals.
All the animals of this phylum are marine and usually found at the bottom of the sea.
This phylum is of great interest because of its close relation to the phylum Chordata.
Starfish, sea urchin, sea lily, and sea cucumber etc are the examples of this phylum.
The animals which have vertebrae spinal cord and notochord are called vertebrates.
In simple words, the animals having a backbone are called vertebrates.
Fish, frog, cat, dog, rat, lion, bat and wolf etc are the examples of vertebrates.
Vertebrate animals belong to the phylum Chordata and subphylum Vertebrata.
The phylum Chordata is further divided into four subphyla on the basis of the development of the notochord.
1. Sub phylum Hemichordata
The animals possess the notochord in the anterior region of their body.
2. Sub phylum Urochordata
The notochord is present in the tall region of the larval stage only but it is not present in the adult stage.
e.g. Polycarpa and hardmania etc.
3. Sub phylum Cephalochordata
The animals belonging to this subphylum have the notochord that extends from the anterior to the posterior part of the body.
e.g. Amphioxus and branchostoma etc.
4. Sub phylum Vertebrata
The notochord is present only during the embryonic stage and it is later replaced by the vertebral column/backbone in the adult stage.
e.g. Bat, sea horse, frog, Hyla, salamander, rabbit and man etc.
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