There are over a million described species of animals known to science, of this number about 5% are known to evolve or possess a vertebrate column and are known are vertebrates. All others, 95%, are invertebrates. The division of life on earth into these two categories reflects a bias in favour of humans own relations to other vertebrates, we could just as easily divided life by arthropods and non- arthropods, this being actually quite a good idea as the latter category contains about 85% of all animal life. Even though they are classed together there is not a single common characteristic that invertebrates hold in common, besides the lack of vertebrate column, as the range of; size, structural diversity, natural range and adaptions being physical or behavioural for survival are enormous. Due to the large range of organisms that are classed under invertebrates a study of them is near impossible, and cannot be classed as a specialist form of zoology as a student of all biological aspects be it reproduction, diet, behaviour, embryology and ecology of 95% of all life on earth would hardly be classed as a specialist. This is why you will rarely find an invertebrate zoologist but you can find specialists such as a protozoologist, arachnologist, malacologist, and entomologist or specialise in a form of study such as physiology, ecology, behaviour or embryology of a range of animals. Due to the sheer size and diversity of invertebrates it is incredible hard to have more than a good general knowledge of the major groups.
It’s not all doom and gloom though for people intrested in all invertebrates this blog will be able to look at all aspects of invertebrate life, general and an in-depth, and even how their lives can change and affect ours from recent discoveries to well-known knowledge.