Crayfish

Kingdom:    Animalia
Phylum:         Arthropoda
Subphylum:      Crustacea

 

Dorsal View of Crayfish

1.  These are the crayfish's uropods. It has two pairs of these appendages.

2.  This is the crayfish's telson, the posterior-most extension of the last body segment. It, in combination with the uropods, is used in rapid, backwards escape swimming.

3.  This is the crayfish's abdomen. Its paired appendages are the swimmerets and the uropods.

4.  This is the crayfish's cephalothorax. It is covered with a heavily mineralized carapace that offers some protection form predators.

5.  This is the cephalic groove, a lateral seam in the carapace between the head and thorax regions.

6.  These are two of 8 (4 pairs) of walking legs. Each walking leg has an attached gill that occupies the animal's branchial chamber.

7.  This is the crayfish's left cheliped. These appendages are used for defense and food handling.

8.  This is the crayfish's left eye.

9.  This region of the carapace is called the rostrum.

a.  This is the crayfish's left long antenna, a sensory organ.

Source:  http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/crayfish_stuff/dorsal_view.html

 

Ventral View of Crayfish

1.  These are the crayfish's uropods. It has two pairs of these appendages.

2.  These are the crayfish's swimmerets. There are five pairs of these appendages.

3.  These are the crayfish's walking legs. There are four pairs of these appendages.

4.  This is the crayfish's right cheliped. These appendages are used for defense and food handling.

5.  This specimen is a male. It's first two pair of swimmerets are elongate and form a sperm transfer organ. In females, the first two pairs of swimmerets are unmodified.

6.  This is the crayfish's right long antenna, a sensory organ.

 Source:  http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/crayfish_stuff/ventral_view.html

 

Detailed Ventral View, Male Crayfish

1.  This is a swimmeret, a short, filamentous appendage.

2.  The pin points to the male genetal opening. Sperm are released here and delivered by the male's modified swimmerets to the female's seminal receptacle.

3.  In the male, the first two pairs of swimmerets are longer, and prong-shaped. They serve as a sperm transfer organ during mating. In this photo, the right modified swimmeret has been pushed aside, while the left one is in place.

4.  This is the base of the fifth pair of walking legs.

5.  This is the base of the fourth pair of walking legs.

6.  This is the base of the third pair of walking legs.

 

7.  This is the base of the second pair of walking legs.

8.  This is the base of the first pair of walking legs, called the chelipeds.

Source:  http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/crayfish_stuff/male.html

 

Detailed Ventral View, Female Crayfish

1.  The arrows point to several swimmerets, short, filamentous appendages that are unmodified in the female.

2.  The arrow points to the seminal receptacle. Sperm received from the male are stored here until the female releases eggs.

3.  This is the fifth pair of walking legs.

4.  This is the fourth pair of walking legs.

5.  The female genital openings are located on the bases of the third pair of walking legs. The arrow points to an opening.

6.  This is the base of the second pair of walking legs.

 

Source:  http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/crayfish_stuff/female.html

 

Branchial View of Crayfish

1.  The arrows show where the gills are attached to each of the five pairs of walking legs.

2.  The carapace covering the right branchial chamber has been removed showing the gills. Water is drawn into the posterior end of this chamber, flows across the gills, and leaves via the anterior end.

3.  This is the cephalic groove, a lateral seam in the carapace between the head and thorax regions.

4.  The arrow points to the right third maxillilped.

5.  This is the crayfish's right cheliped. These appendages are used for defense and food handling.

6.  This is the crayfish's right eye.

7.  This region of the carapace is called the rostrum.

8.  This is the crayfish's right long antenna, a sensory organ.

Source:  http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/crayfish_stuff/branchial.html

 

Cephalothorax (Dorsal View) - Crayfish

1.  The arrow points to a gill within the exposed branchial cavity.

2.  The arrow points to the crayfish's heart.

3.  The arrow points to a portion of the crayfish's hepatopancreas gland.

4.  The arrow points to the mandibular adductor muscle. It was attached to the inner surface of the carapace. It's contraction causes the mandibles to come together.

5.  The arrow points to the gastric stomach, the portion of the digestive system containing the gastric mill, a chitinous arrangement of teeth, files, and sieves used to grind up the food.

6.  The arrow points to the crayfish's right eye.

Source:  http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/crayfish_stuff/cephalothorax.html

 

Cephalothorax, Deeper View - Crayfish  (Note: the mandibular muscles, much of the hapatopancreas gland, and the stomach has been removed to reveal deeper structures.)

1.  The arrow points to a portion of the crayfish's hepatopancreas gland.

2.  The arrow points to a green gland. These osmoregularoty organs secrete excess water and ammonia. The filtrate exits via the renal pore.

3.  The arrow points to the cut gut tube at the level of the esophagus. The stomach has been removed.

4.  The arrows point to the circumesophageal connections of the ventral nerve cord. The brain is anterior and not visible. The nerve cords leave the brain, encircle the esophagus, and become the ventral nerve cord, characteristic of the arthropods.

Source:  http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/crayfish_stuff/green_glands.html

 

Abdomen - Crayfish

1.  These are the crayfish's uropods. It has two pairs of these appendages.

2.  This is the crayfish's telson, the posterior-most extension of the last body segment. It, in combination with the uropods, is used in rapid, backwards escape swimming.

3.  These are the crayfish's abdominal flexor muscles. They provide the major force for rapid backwards swimming by flexing the tail.

4.  These are the crayfish's intestine.

5.  The arrow points to the porterior portion of the crayfish's right branchial chamber.

 

Source:  http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/crayfish_stuff/tail.html

 

Cephalothorax, Lateral View - Crayfish

1.  The arrows point to the cut bases of walking legs 3, 4, and 5.

2.  This is the right branchial chamber. The gill filaments have been trimmed to reveal deeper structures.

3.  The arrow points to the heart. Look below to see an isolated crayfish heart.

4.  The arrow points to a portion of the crayfish's hepatopancreas gland.

5.  The arrow points to the stomach. Look below to see a dissection of the gastric mill within the cardiac portion of the stomach.

Source:  http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/crayfish_stuff/lateral_view.html

 

Crayfish Heart  (Note: the arrow points to an opening (ostium) through which blood enters the heart. There is a pair of ostia on each side.)

Source:  http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/crayfish_stuff/heart.html

 

 

 

 

 

Crayfish Gastric Mill

 

Note: the cardiac stomach has been cut open ventrally and rinsed out. You are looking at the interior, dorsal surface. The arrows point to two sets of chitinous lateral teeth and a set of medial teeth. Muscles move this gastric mill to mascerate food before it is passed on to the pyloric stomach.

Source:  http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/crayfish_stuff/stomach.html

 

 

Below are diagrams you can click on with very detailed information about Crayfish. 
Source:  Wards Biology Clip Art CD.  (Color Diagram from Prentice Hall, Biology Transparency Book)