Natural classification of animals mention 2 types of animals according to their phylum. Vertebrates and Invertebrates are those 2 main types of animals. Vertebrates are the animals who do have a vertebral column and invertebrates are the animals who don’t have a vertebral column. We have discussed about vertebrates and its 5 types on Smart Science Pro.
Therefore, we’re going to concentrate on Invertebrates in this post.
A natural classification has few characteristics and all the classifications of this system are following those. So here are the features of this type of animals.
Characteristics of Invertebrates
Since now you realize who are invertebrates, it’s good to learn their other characteristics too. May be your science exam would ask these or you may want to clarify some animal’s type.
- Don’t have a vertebral column or spinal cord or backbone.
- Usually these are little and slowly moving animals.
- Presence of no lungs to respire since they do it through the skin.
- Invertebrates are heterotrophic since they can’t produce their own food.
- Reproduction is through fission of gametes.
- Some posses a hard exoskeleton.
- Multicellular organisms live on many environments.
Invertebrates includes every animal that doesn’t belong to vertebrates group. There are 4 main types of invertebrates as mentioned below by Phylum.
- Phylum Arthropods
- Phylum Mollusca
- Phylum Annelida
- Phylum Coelenterata
Each group have their own characteristics and unique adaptations. I’ll explain each of them below.
Arthropods are animals who do have a segmented body. They have a bilaterally symmetrical body with a very strong exoskeleton. Arthropods have the ability of adapting to various environments very quickly.
A pair of appendages can be seen in each segment of the body. There are jaws appear in some of the appendages.
Examples for Arthropods,
– Honey bee
Unlike arthropods these animals don’t have segmented body. Mollusca skin has a mantle which secrets a shell. Their skin is soft and the body is bilaterally symmetrical. Mollusca can be found in fresh water and sea water.
Examples for Mollusca,
Annelida group contains many of the worms around. They have segmented bodies made up of 3 layers, hence they can be known as Triploblastic animals. Triploblastic means they have 3 layers of skin as outer skin, middle skin and inner skin.
Annelida group animals have a cuticle which covers their skin. They posses coelem and hard bristles and the reproduction is sexual.
Examples for Annelida,
– Polychaete worms
Coelentarata animals have a radially symmetrical body. They are opened through the mouth to external atmosphere. These are diploblastic animals which means their body is made up of 2 layers called Ectoderm Skin and Endoderm Skin.
Presence of a central gastro vascular cavity used as the mouth and anus which is lined by Endoderm skin. Some coelentarata animals do have poisonous substances mixed special cells known as Endoblasts which protects them.
Examples for Coelnterata,
– Sea Anemones
– Sea Wasps