Scorpion Anatomy

Prosoma: The anterior part of the body or anterior cephalothorax (the combined head and thorax).

Mesosoma: Also pre-abdomen. Forms together with the metasoma the opisthosoma (or abdomen). The mesosoma is the middle part of the body and is divided into 7 segments. Each segment is divided into a tergite (dorsal), a sternite (ventral), and two pleurites (lateral).

Metasoma: Also post-abdomen (or tail). Forms together with the mesosoma the opisthosoma (or abdomen). The metasoma is divided into 5 segments and the telson. Each segment is divided into a tergite (dorsal), a sternite (ventral), and two pleurites (lateral). The telson is not a segment.

Carapace: Hard outer covering (or shield) on the dorsal section of the cephalothorax.

Tergite: A dorsal sclerite (a hardened plate into which the exoskeleton is divided) of a segment.

Chelicerae: The jaws or the first pair of appendages of the cephalothorax. They are divided into 3 segments: coxa, tibia (or fixed finger) and tarsus (or movable finger). Used to grab and crush the prey.

Lateral eyes: Pairs of small eyes on the lateral (the side) corners of the carapace.

Median eyes: 2 eyes in the middle of the carapace.

Telson: The telson is located after the fifth metasomal segment and is divided into the vesicle and the curved aculeus. The telson is not a true segment, like the 5 segments of the metasoma.

Vesicle: A sac containing the paired venom glands.

Aculeus: A curved needle (or sting) at the vesicle.

Trochanter: Second segment of the pedipalp between the coxa and femur.

Femur: The third segment of the leg or pedipalp between the trochanter and patella.

Patella: The fourth segment of the leg or pedipalp between the femur and tibia.

Tibia: The tibia is the large fixed finger of the chela. It is the fifth segment of the pedipalp after the patella.

Tarsus: The tarsus is the movable finger of the chela. It is the sixt segment of the pedipalp after the tibia.

Setae: Sensory 'organ'. A very fine hair (or bristle) for 'feeling/sensing' vibrations in the air.

Granulation: Covered with grains (a small knob-like elevation).



Pedipalp: The second pair of appendages of the cephalothorax. They are used in prey capture, defense and mating. The pedipalp is divided into coxa, trachanter, femur, patella, tibia and tarsus. The tibia and tarsus forms the chelae of the pedipalp.

Sternum: The sternum is a ventral plate where the coxae of most legs meet. The form of it is used to differentiate the scorpion families.

Genital operculum: A lid that covers the reproductive organs. The form of the genital operculum can be used to determine the sex.

Pectines: Used in selecting places for dropping spermatophores (a packet containing sperm) and for sensing textures of substrate. The pectines are made up of a basal plate with 2 combs on it.

Pectines teeth: Rows of teeth along the rachis (or main branch) of the pectines. These teeth are covered with sensory structures (peg sensillae).

Sternite: A ventral sclerite (a hardened plate into which the exoskeleton is divided) of a segment.

Spiracles: Holes located on the lateral surface of the sternite which opens into a book lung (respiration organ). These book lungs contain hollow leaf-like structures through which the blood flows.

Coxa: The coxa is where the leg and the cephalothorax come together. It is the first segment of the leg.

Trochanter: Second segment of the leg (or pedipalp) between the femur and coxa.

Femur: The third segment of the leg (or pedipalp) between the trochanter and patella.

Patella: The fourth segment of the leg (or pedipalp) between the femur and tibia.

Tibia: The fifth segment of the leg (or the fixed finger of the chela) after the patella.

Basitarsus: The sixth segment of the leg between the tibia and tarsus.

Tarsus: The last segment of the leg after the basitarsus (or the movable finger of the chela).

Ungues: Or claws.



Chelicerae: The jaws or the first pair of appendages of the cephalothorax. They are divided into 3 segments: coxa, tibia (or fixed finger) and tarsus (or movable finger).

Tergite: A dorsal sclerite (a hardened plate into which the exoskeleton is divided) of a segment.

Carapace: Hard outer covering (or shield) on the dorsal section of the cephalothorax.

Median eyes: 2 eyes in the middle of the carapace.

Lateral eyes: Pairs of small eyes on the lateral corners of the carapace.

Granulation: Covered with grains (a small knob-like elevation).





Reference: Alan Mommerency - [You must be registered and logged in to see this link.]

nice info. about scorps.