Do you have any idea about how many animal species are there on Earth? There are as many as 30 million animal species alive. It always excites an individual to learn more about these species, but it's pretty a challenging task too. As there's enormous number of species, it becomes tough to bear in mind each one of them. So, to have a clearer idea, you can segregate these species of animals into 6 basic groups.
Invertebrates are the first animal species category. The name of the category itself suggests that invertebrates do not have a vertebral column or a spine. Most of the back pain sufferers may as well wish that they were born without a spine too. Flatworms, micro-organisms, insects and so on are some of the species, which fall under this group.
Fishes is another animal group. They were the 1st vertebrates to evolve. Fishes could be broadly classed into cartilaginous fish, ray finned fish and lobe finned fish. Amongst the three, it's ray finned fish that's the most versatile and has 24,000 species. If you want an additional pet along with your pet dog, then fishes are a great choice.
Another broad category of animal is amphibians. These are the animals that live both- on land and water. The first amphibians developed from lobe finned fishes, approximately 370 million years ago. Approximately, there are 5000 to 7000 species of amphibians. Some animals that fall in this category include frogs, salamanders and the like.
One of the most critical categories of species of animals is Reptiles. These cold blooded vertebrates exhibit two varying features. One of their traits is that they have scales all over their body and the other is that they produce hard eggs. 1st amphibian came into existence 340 million years ago. Some of the popular amphibians are crocodiles, tuataras, squamates, turtles, etc.
Now the other and the most developed category of animals is Mammals. These species exhibit a varied selection of characteristics like they are pretty adaptable and they can acclimatize to an array of habitats. 5,400 mammals are alive today. In addition, this category of species is quite diverse. Small Bumblebee Bat that is three centimeters is a mammal; on the other hand, 33m long blue whale is also a mammal. Are you conscious of the fact that human beings too are mammals?
When we chat about animals, we also talk about birds. There are a lot of birds that are animals and that can also fly. Moreover, birds have unique characteristics that make them different from the others. These features are furcula, feathers, bills, etc. Flying birds give a feel of contentment. So, bird watching is a hobby for many individuals. You can also enjoy bird watching, without any worries regarding sun tan.
Knowing more about several categories of animas is enriching really.