WHAT ARE INVERTEBRATES?

Characteristics of Invertebrates

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General characteristics of invertebrates are as follows:

• The main characteristic that separates invertebrates from other organisms is the absence of the spinal column and backbone.
• They are multicelluar organisms, they completely lack cell walls.
• They are devoid hard bony endoskeleton. 
• Due to the lack of complex skeletal systems, some invertebrates tend to be slow and small in nature. 
• Due to the lack of the backbone and complex nervous system the invertebrates cannot occupy mulitple environments, though they are found in the harshest of the environments. 
• Invertebrates live all over the world in various habitats.
• Body is divided into three parts - head, thorax and the abdomen.
• They do not have lungs for respiration.
• Respiration is through skin.
• Some invertebrate groups possess a hard, chitinous exoskeleton. 
• Most of them have tissues, that are specific organization of cells.
• Most of them reproduce sexually by the fusion of the male and female gametes. 
• Few invertebrates like the sponges are sedentary, but most of the organisms are motile. 
• Most invertebrates are organized with symmetric body organization.
• They can not make their own food, are heterotrophs.