The document provides a comprehensive guide for educators on conducting crayfish dissections, highlighting the benefits of using video and PowerPoint presentations to enhance the learning experience while prioritizing safety. It outlines essential safety procedures, anatomy of the crayfish, and step-by-step dissection instructions to ensure the activity is educational and secure for students. The document emphasizes ethical considerations and the importance of accommodating students who may not participate in physical dissection.

1. Reasons to Use the Dissection Video and
Accompanying PowerPoint Presentation
 Reduce the number of specimens used by a class
 Increase the quality of the dissection for the students
 Review opportunity, increasing the learning experience
for the students
 Student unable to dissect due to pregnancy or
hypersensitivity to the preservatives
 Student chooses not to dissect due to ethical/moral
reasons
Dissection 101:
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2. Dissection 101:
As an educator you are responsible for the implementation
of the dissection activity described in the video and
PowerPoint. You must have safety procedures and rules
established for your classroom and make sure all of the
students follow the rules to ensure a safe environment.
South Dakota Public Broadcasting and Dakota State
University cannot in any way be responsible or liable for
any injury as a result of performing the described
dissection. Complete the dissection if you feel it is
appropriate and safe for your individual class.
Have fun and stay safe!
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Safety Considerations
 Age appropriate activity for the children in your care
 Safety Data Sheet (SDS) available for accident reference
 Poison control number/phone readily available
 Latex free gloves, eye protection and apron/lab coat
 Eyewash station, shower and sink
 Sharp instruments (cut away from self and others)
 Sharps and specimen(s) disposal
 Encourage students to report all accidents
 Basic science laboratory rules (strictly enforced)

3. Click
Dissection 101:Crayfish
Crayfish are arthropods, which are the most
diverse and abundant group of animals on
earth. There are more species of arthropods
than all other animals combined.

4. Click
Dissection 101:Crayfish
Arthropod characteristics:
o Jointed appendages – bend to move in specific directions
and specialized for specific jobs
o Exoskeleton – hardened cuticle, which is an outside layer of
skin; it is nonliving tissue called chitin that does not grow
with the body and must be removed for growth in a process
called molting (shedding)
o Body segmentation – specific regions

5. Segmented Body Plan (2 main regions)
Cephalothorax – head and thorax region
Abdomen – segmented tail
Exterior of the Crayfish
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The telson and uropods form the
flipper-like structure at the end of the
abdomen (tail); used to propel the
crayfish in a backward direction by
whipping the tail forward
(third law of motion)
Telson
Uropods
Tail movement
Crayfish movement

6. Exterior of the Crayfish
Chelipeds (pinchers) – 1st of the
paired walking legs; modified for
defense, fighting, and capturing
prey (can regenerate, but slow)
Carapace -
specialized
portion of the
exoskeleton;
covers the head
and thorax
regions
Antennae – 2 pair, smaller
anterior paired called antennules;
used for taste (chemicals in
water) & touch
Rostrum – anterior section of
carapace; protects eyes/head
Walking legs – 4 pair of
jointed legs for movement
Smaller regenerated
cheliped
1st pair of smaller walking
legs also has a pincher
Click
Ventral
view

7. Click
Exterior of the Crayfish
Maxillipeds – 3 pair
of larger appendages
near mouth; handle
food
Mandibles – Jaw like
structure; break
food apart; move
side to side
Videos of Mouthparts (Parts / Eating)

8. Click
Exterior of the Crayfish
Male (R) – First 2 pair of
swimmerets are
hardened/enlarged
(copulatory swimmerets);
used to deposit sperm
from opening of sperm
duct to seminal receptacle
of female
Swimmerets - structures
used to help propel
crayfish through the
water; move water across
gills; hold fertilized eggs
and larva in females
Female (L) – Has a
seminal receptacle which
is an opening to the
female reproductive
system (eggs expelled
and held by swimmerets
after they are fertilized)
Female Northern Crayfish Carrying Eggs
(Photo courtesy Missouri Department of Conservation)
Anus – Complete digestive system

9. Click
Getting Started
 Use water to rinse the excess preservative from
your specimen
Dissection 101: Crayfish

10. (YouTube Version)
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Getting Started – Initial Cuts
Dissection 101: Crayfish

11. Click
Getting Started
 Use a scissors to cut the carapace along the side of the crayfish
toward the eye (repeat for other side); then make a third cut at the
anterior of the crayfish connecting the first two cuts; additional
photos to following (click to proceed through photos)
Dissection 101:Crayfish
Always cut away
from yourself

12. Dissection 101:Crayfish
Click
Repeat for other side
Connect the first two cuts
Carefully remove the carapace
Cut the carapace along the side

13. Click
Dissection 101:Crayfish
Gills - Feather-like structures (increased surface area)
used for respiration; remove oxygen from water

14. Click
Dissection 101:Crayfish
Heart (may be attached to the carapace) Gills have been
removed; open circulatory system; keeps blood moving
under low pressure

15. Click
Dissection 101:Crayfish
Digestive gland – Produce enzymes to digest food;
also absorption of nutrients

16. Click
Dissection 101:Crayfish
Cardiac
Stomach
Pyloric
Stomach
Cardiac
Stomach
Pyloric
Stomach
Side View
Digestion
Gland
Gills
Stomach – Storage and digestion – 2 chambered: cardiac
stomach is anterior (closer to the mouth), has a gastric mill
which is a teeth-like structure used to break food into smaller
pieces; pyloric stomach connects to the intestine

17. Dissection 101:Crayfish
Exposing the Antennal Glands
(YouTube Version)
Click

18. Dissection 101:Crayfish
Click
Stomach removed
Closeup of gastric mill found
within the cardiac stomach

19. Dissection 101:Crayfish
Crayfish with Stomach Removed
Antennal glands (green glands) -
Paired; excretion of body wastes
(equivalent to urine)
Click
Ganglia:
Nervous
tissue

20. Dissection 101:Crayfish
Exposing the Intestine
(YouTube Version)
Click

21. Click
Dissection 101:Crayfish
Cut along both sides of the abdomen (tail)
Remove the exoskeleton
(do not damage the intestine)
Intestine: Passage of undigested
food from the stomach to the anus
(complete digestion)
Muscle

22. Dissection 101:
Produced by Dakota State University
and South Dakota Public Broadcasting
Crayfish
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