How are invertebrate animals
The planet Earth is populated by a huge 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 . By invertebrates we know those members of the animal kingdom that " lack a spine or an articulated internal skeleton" . For some it may seem strange, but the majority group are invertebrates. From this article of .com we will try to know more about how invertebrate animals are.
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Recent studies claim that invertebrate animals represent 95% of the animal species existing on planet Earth. Within this overwhelming figure hides a huge variety of edges, types, groups, etc ...
We could start talking about the arthropods, the most numerous edge 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 .
The insects are characterized by having a body divided into the head, thorax and abdomen. Other features are its 2 antennas on the head and its 6 legs. On the other hand, the arachnids stand out for being vertebrate in cephalothorax and abdomen and they have 8 legs. Crustaceans are similar to arachnids but most have 10 legs and are usually aquatic. The miriápodos have the body divided between head and trunk, this being formed by many articulated rings.
Another quite numerous edge are the molluscs . They are characterized by a soft body. Some have an external shell and others an internal shell. The three main groups are the gastropods, the bivalves and the cephalopods .
The following groups of invertebrates are somewhat less numerous. It's about worms, echinoderms (like starfish), jellyfish and sponges .