Special Edition #1: Insect Anatomy

Day 2 of Beetles. A little about insect anatomy and beetles in particular. Insects are Arthropods, which means "jointed leg", and all Arthropods are divided into segments. The insect body plan has evolved through the process of specialization of the segments, this is called tagmosis. All insects are divided into three regions: head (front), thorax (middle), and abdomen (end).

Head:
The head is composed of approximately 6-7 highly modified segments fused together. Each mouthpart, antennae and the labrum and clypeus represent a segment, as does the remainder of the head. The image below is one I took of a specimen of mine, it is a Tiger Beetle called Cicindela trifasciata and happens to show all the major parts of the head anatomy very clearly.

Thorax:
The thorax of insects is composed of three segments, dived into the prothorax (front), mesothorax (middle) and metathorax (end). Each segment bears a pair of legs and the second and third segments have a pair of wings each. In beetles the plan is the same, but there are some special features that deserve mention to further understand what I'm talking about. In beetles, the plan is the same but looks different than in other insects. The top part of the prothorax is usually very pronounced and is referred to as the pronotum. The "abdomen" of a beetle is really the combination of the last two segments of the thorax and the abdomen together. They are covered up by the hardened first pair of wings called elytra. These aren't used for flight, and beetle rely on their hind wings for flight.

Abdomen:
The abdomen is fairly unsepcialized and can up to 11 segments long including genitalia, but many have fewer. In beetles the abdomen is usually covered by the elytra, though groups like the Rove Beetles (Staphylinidae) have very abbreviated elytra.

Hopefully this little tutorial will be helpful as I go through the insects. I'll mention other details as they arise

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Abdomen:
The abdomen is fairly unsepcialized and can up to 11 segments long including genitalia, but many have fewer. In beetles the abdomen is usually covered by the elytra, though groups like the Rove Beetles (Staphylinidae) have very abbreviated elytra.

Hopefully this little tutorial will be helpful as I go through the insects. I'll mention other details as they arise