Crayfish / Crawfish / Crawdads Morfology / Anatomy

Crayfish (also known as crawdads, crawfish, mudbugs, or yabbies), are common throughout the world. There are  over 400 difference species of crayfish, 330 of which are native to the United States. Crayfish are commonly used  as food, bait,

and pets. 
Like all crustaceans, a crayfish has a fairly hard exoskeleton that covers its body. As shown in the  diagram, its body is divided into two main parts, the cephalothorax and the abdomen. 
The cephalothorax consists of the cephalic (or head) region and the thoracic region. The part of the
exoskeleton that covers the cephalothorax is called the carapace. 
The abdomen is located behind the cephalothorax and consists of six clearly divided segments. The cephalothorax consists of 13 segments. Each segment of both the cephalothorax and the abdomen contains a pair  of appendages. 
The head (or cephalic) region has five pairs of appendages. The antennules are organs of balance, touch,
and taste. Long antennae are organs for touch, taste, and smell. The mandibles, or jaws, crush food by moving  from side to side. Two pairs of maxillae hold solid food, tear it, and pass it to the mouth. The second pair of  maxillae also helps to draw water over the gills.  

Of the eight pairs of appendages on the cephalothorax, the first three are maxillipeds, which hold food
during eating. The chelipeds are the large claws that the crayfish uses for defense and to capture prey. Each of the  four remaining segments contains a pair of walking legs. In the abdomen, the first five segments each have a pair  of swimmerets, which create water currents and function in reproduction. The sixth segment contains a modified  pair of uropods. In the middle of the uropods is a structure called the telson, which bears the anus. The uropod  and telson together make up the tail fan. The crayfish moves backward by forcing water forward with its tail fan. 

Encephalon: site of the mental functions of a crayfish / crawfish / crawdads.
Stomach: part of the digestive tract between the esophagus and the intestine.
Heart: blood-pumping organ of the crayfish / crawfish / crawdads.
Gonad: sex gland of a crayfish / crawfish / crawdads.
Extensor muscles: muscle that extends the tail of the crayfish / crawfish / crawdads.
Anus: outlet of the digestive tract.
Flexor muscle: muscle that bends the tail of the crayfish / crawfish / crawdads.
Digestive gland: glandular organ that produces digestive enzymes.
Ganglion of ventral nerve cord: budge related to a collection of nerves of the abdomen of a crayfish / crawfish / crawdads.
Ventral nerve cord: collection of nerves in the abdomen of a crayfish / crawfish / crawdads.
Maxilliped: pair of appendages of a crayfish used for holding prey.
Esophagus: part of the digestive tract between the mouth and the stomach.
Mandible: lower jaw.
Mouth: entrance to the digestive tract.
Green gland: antennary gland.
Eye: sight organ of a crayfish / crawfish / crawdads