M-16: Squid Dissection
Overview: Students dissect a squid and learn more about its
anatomy.
An activity from the
Environmental Volunteers
Program Area:
Marine Ecology
Grade Levels:
3-6
EV Learning Objectives:
1. Squid have many unique
features both internally and
externally that help them to
survive.
EV Sustainability Principles
E. Understanding the beauty of
our planet, the elegance of
natural systems, and the
interconnectedness of all its
parts.
MATERIALS LIST
Dissection scissors
Tweezers
Probes
Plastic disposable plates
Paper towels
Wet wipes
Magnifying glasses
Newspapers or other table cover
Tape
Pencils
Student worksheets
Key for student worksheets
Pictures of male and female dissection samples
Snack sized ziplocs
Labels for ziplocs
To purchase before class
fresh or frozen whole squid available at a fish market or grocery
CALIFORNIA EDUCATIONAL STANDARDS
All standards are for science unless otherwise noted. 1
Third Grade
• 3a. Students know plants and animals have structures that
serve different functions in growth, survival, and
reproduction.
Fifth Grade
• 2a. Students know many multicellular organisms have
specialized structures to support the transport of materials.
• 2c. Students know the sequential steps of digestion and the
roles of teeth and the mouth, esophagus, stomach, small
intestine, large intestine, and colon in the function of the
1
Note about EEI Learning Objectives: this learning station supports these objectives of the Education
and the Environment Initiative’s Environmental Principles and Concepts. As the learning objectives do
not have their own numbering convention, the one used here show the number of the standard before the
dash and the number after the dash is the bullet point from the list of objectives for that standard.
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digestive system.
ACTIVITY
Note: This activity is written up as a double station. You have 30 minutes for the
activities. Usually there are two stations committed to squid dissection. Half the
students do this while the other half rotate through two other stations.
BEFORE CLASS SET UP
Buy frozen squid for the dissection and be sure they are thawed (but still cold) by class time.
Use newspapers to cover the area where the students are working. The tape can be used to secure
the newspaper.
If you are going to give students the option take home the pen or eyes of the squid, put labels on
the ziplocs. This gives a place to put the student’s name, as well as a hint of what it is when they
get it home.
INTRODUCTION
(Time required: 2-4 minutes)
ASK:
ASK:
ASK:
ASK:
ASK:
EXPLAIN:
What do you know about squid?
How does it eat?
How does it swim? How does it steer
How does it protect itself?
Is it male or female? How can you tell?
We find out the answers to these questions (and find out how much you knew!)
by the time we are done with our dissection.
ACTIVITY 1: External Anatomy
(Time required: 12-15 minutes)
DO: Give each pair of students a squid on a plate, and each student a worksheet, and a
pencil.
ASK: What is something you observe about the external anatomy of your squid?
RESPONSE: As students offer their answers, discuss each one in turn as suggested below.
Guide them with questions to any that they miss. Have the students fill in their
worksheet as you discuss each one.
Fin: There are two fins on each side of the head that help the squid stay stable and steer when
swimming.
Mantle: The main part of the squid’s body. It covers most of the major internal organs.
Chromatophores: The spots on the skin, which can change color to aid in finding a mate,
camouflage, or in warning other squid. It does this by the spots changing size.
Pen: The squid is related to other "shelled" animals like clams and snails. The pen is all that is
left of the shell the squid's ancestors once had.
DO: Have the students scrape the skin back from the tip of the pen and then use their
tweezers to pull it out. They may have to pull fairly hard to get it out.
Eyes: Squid eyes are structured like human eyes (unlike something like a fly’s compound eye),
and they can see about as well.
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DO: Have the students see if they can dissect out the eye. It will be a tiny, clear pearl
that is easily lost, so they should be careful. When they get it out, let them tape it
to their worksheet.
Arms/Tentacles:
ASK: How many arms do squid have?
RESPONSE: Typically it is said squid have 10 arms. (Octopi have 8.)
ASK: Take a look at the arms. Are they all the same?
Arms: These are the 8 shorter appendages, which are covered in suction cups.
Tentacles: These are the 2 longer appendages, which only have suction cups at the tips and are
used to pass food to the arms and then to the mouth.
Suction cups: Used for holding onto food.
Beak: (on the internal side of the worksheet) the squid’s mouth.
DO: Have the students pull back the arms to locate the beak. They can remove the
beak if they want.
ACTIVITY 2 Internal Anatomy
(Time required:10-12 minutes)
DO: Instruct the students to position the squid on the plate with the siphon facing up.
DO: Ask students to make one long incision from the bottom of the mantle, above the
siphon, to the tip of the mantle next to the fins. Be sure to instruct the students to
lift up with their scissors when cutting so as not to cut into the internal organs of
the squid.
ASK: What is something you observe about the internal anatomy of your squid?
RESPONSE: As students offer their answers, discuss each one in turn as suggested below.
Guide them with questions to any that they miss. Have the students fill in their
worksheet as you discuss each one.
Siphon: Squirts out water to help propel the squid like a jet plane.
Brain: The brain is highly developed for an invertebrate.
Ink sac: The squid will squirt ink out through its siphon when in danger.
DO: Have students cut open the ink sac and then use the squid’s pen to write their
name on their worksheet (just like an old fashion quill). Be sure that one student
doesn’t use up all of the ink before their partner has a chance to try it.
Heart: Circulates blood like in other animals.
Gills: Absorbs oxygen from the water.
Gonad: The reproductive organ. The male’s is white, and the female is clear. (See photos for
reference)
DO: Have students look at each other’s squid to be sure they see both a male and a
female. After the first group, save one of each just in case you don’t get both in
the next group. You can also check the group that is doing the station in parallel
with you, or the laminated photos if you have to.
TWO-MINUTE WARNING
(Time required: 2 minutes)
You may start this before your 2 minute warning so you have enough time to clean up.
EXPLAIN: Let’s see if we know more about the questions we discussed at the beginning.
ASK: How does it eat?
RESOPNSE: It pulls things in with it’s tentacles and arms and chews them with its beak.
ASK: How does it swim? How does it steer
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RESOPNSE: It pushes water out through its siphon and uses the fins to steer.
ASK: How does it protect itself?
RESOPNSE: It can camouflage with the chromatophores or it can squirt ink to blind a predator
and escape.
ASK: Is it male or female? How can you tell?
RESOPNSE: You can look at the gonads on the inside. The male’s is white, and the female is
clear
CLEAN UP
Squid and table covers are thrown away.
Between sessions wipe down the tools and plates. At the end, wash everything thoroughly,
including wiping down the script, etc. Leave the tools in the cloth bag to dry.
Students should wash their hands before going to the next station.
ALTERNATE SCRIPTS
HELPFUL HINTS
If you will not have two rotations to do this kit, spend less time on each body part, skip some
(like the brain, beak, eyes, etc.), let students write just one letter with the ink or skip that step all
together.
GLOSSARY
Fin: on each side of the head that help the squid stay stable and steer when swimming.
Mantle: The main part of the squid’s body. It covers most of the major internal organs.
Chromatophores: The spots on the skin, which can change color to aid in finding a mate,
camouflage, or in warning other squid. It does this by the spots changing size.
Pen: The pen is all that is left of the shell the squid's ancestors once had.
Arms: These are the 8 shorter appendages, which are covered in suction cups.
Tentacles: These are the 2 longer appendages, which only have suction cups at the tips and are
used to pass food to the arms and then to the mouth.
Suction cups: Used for holding onto food.
Beak: the squid’s mouth.
Siphon: Squirts out water to help propel the squid like a jet plane.
Ink sac: The squid will squirt ink out through its siphon when in danger.
Gills: Absorbs oxygen from the water.
Gonad: The reproductive organ. The male’s is white, and the female is clear.
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SCIENCE BACKGROUND
The squid is one of the most highly developed invertebrates. Some of the animal structures
explored in this lesson illustrate the ways in which the squid has adapted to life in the ocean. Its
streamlined body and jet propulsion, which occurs as the squid squeeze water out of its body
through its siphon, make the squid a fast, active predator. This animal also has a very good
defense mechanism.
All mollusks have a soft body with a special covering called the mantle, which encloses
all of the body organs such as heart, stomach and gills.
• Squid can be as small as a thumbnail, or as large as a house. The giant squid,
Architeuthis, can measure 60 ft. in length and weigh three tons!
• Squid have ten arms, which are wrapped around the head. Eight are short and heavy, and
lined with suction cups. The ninth and tenth are twice the length of the others, and are
called tentacles. Suction cups are only on the flat pads at the end of the tentacles.
• Squid feed on small crustaceans, fish, marine worms, and even their own kind! They use
their tentacles to quickly catch their prey, which is pulled in by the arms and down to the
radula, or beak, which uses a tongue-like action to get food to the mouth so it can be
swallowed whole.
• Squid are a major food source for many fishes, birds and marine mammals.
• Squid produce a dark ink that they use to escape from predators. When a squid is
startled, the ink is released through the anus, and the cloud of inky water confuses the
predator while the squid swims away.
• After mating, a female squid will produce 10-50 elongated egg strings, which contain
hundreds of eggs each. In many species, the parents will soon die after leaving the
spawning ground. The egg strings are attached to the ocean floor, are left to develop on
their own, and hatch approximately ten days later.
• Squid are an important part of the ocean food web. Squid are gaining popularity as a
food source for humans around the world. Overfishing is a growing concern because
there are no regulations on squid harvesting.
• Southern California squid populations spawn mainly in the winter (December to March).
Squid are seined commercially at their spawning grounds. About 6,000 metric tons are
taken yearly for human food and bait.
This kit was greatly inspired by an activity by the Natural History Museum of Los Angeles.
http://www.wbrschools.net/techcds/webpage%20science78/Life%20Science/Squid%20Infor
mation%20G7%20GLE%2023.pdf
A good video showing many of the same things we do:
http://video.google.com/videoplay?docid=7230364635680690685#
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EV SUGGESTS- TIPS, TRICKS, AND NEWS
REFERENCES
Female photo: http://wwwbio200.nsm.buffalo.edu/labs/tutor/Squid/Squid62D.html
Male photo: http://wwwbio200.nsm.buffalo.edu/labs/tutor/Squid/Squid29D.html
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