Planet Earth is populated by an enormous variety of living beings. There are also many ways to group or catalog them. A very common classification is the one that distinguishes them between vertebrates and invertebrates. Invertebrates are those members of the animal kingdom that “lack an articulated backbone or internal skeleton”. For some it may seem strange, but the majority group are invertebrates. From this uncomo.com article we will try to learn more about what invertebrate animals are like.
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Recent studies affirm that invertebrate animals represent 95% of the animal species existing on planet Earth. Within this overwhelming figure hides a huge variety of phyla, types, groups, etc …
We could start talking about arthropods, the most numerous phyla of the animal kingdom. The term is applied to invertebrate animals endowed with an external skeleton and articulated appendages. Within the arthropods the main groups are insects, arachnids, crustaceans and myriapods.
Insects are characterized by having a body divided into head, thorax and abdomen. Other features are its 2 antennae on the head and its 6 legs. On the other hand, arachnids stand out for being vertebrates in cephalothorax and abdomen and have 8 legs. Crustaceans are similar to arachnids but most have 10 legs and are usually aquatic. Myriapods have the body divided between head and trunk, this being formed by many articulated rings.
Another quite numerous phyla are molluscs. They are characterized by a soft body. Some have an external shell and others an internal shell. The three main groups are gastropods, bivalves and cephalopods.
The following groups of invertebrates are somewhat less numerous. These are worms, echinoderms (such as starfish), jellyfish and sponges.
If you want to read similar articles to How are invertebrate animals, we recommend that you enter our category of The Animal World.