Download Name___________________________ Squid (Loligo pealeii

Name________________________________
Squid (Loligo pealeii) Dissection Lab
Background information:
There have always been folktales about giant creatures with long arms that live in the
depths of the sea. Squid belong to a large group of marine animals called mollusks.
They vary in size from 5 cm. to 6 meters. The giant squid is the largest of all
invertebrates.
Questions:
1. Squid belong to a group called
2. Squid range in size from
3. _________________ is a word meaning sea or related to sea.
Body characteristics of the squid
Squid have a body shaped like a cylinder with a head attached to one end. On the head
there are ten arms. Of these ten arms, two are much longer and have suction cups near
their tips. Below the head is the squids’ body which is covered by a mantle. On the
mantle are two lateral fins. The shell usually associated with other mollusks is only a
tough transparent structure inside the mantle called the pen.
The circulatory system of the squid is a system of veins and arteries. Their blood is not
based on hemoglobin (which contains iron and makes our blood look red) but instead is
copper based (hemocyanin) which makes their blood appear green.
Questions:
4. The squid’s body is shaped like a _________________.
5. How many arms do squid have?
6. What is a pen?
7. What color is squid blood?
Why?
Nervous System
Squid have a large brain protected by cartilage-like shields in their head. The brain is
complex and controls the sense organs, body parts and behavior of the squid. The squid
has huge nerve cells that coordinate the mantle and arms.
Questions:
8. The brain controls _____________________, _____________________ and
______________________________.
9. What protects the squid’s brain?
How squid move
Squid are powerful swimmers. Some squid are capable of reaching high speeds and are
able to leap 3 meters above the water. To move they allow water to enter the mantle
cavity, when the mantle is contracted the spaces are closed and water is forced through a
funnel propelling the squid through the water.
Questions:
10. How does water enter the squid’s body?
11. Which part of the body moves through the water first the mantle or the head?
How do Squid eat?
Squid grasp their prey with the suction cups on their arms, bringing the prey to their
mouths and attack it with their strong beak like jaws. The food is then broken down by
the radula, a toothed organ in their mouth.
Defense
Squid are the favorite food of many sea animals such as fish and sea mammals. To get
away the squid will first release a fluid called ink. This confuses the attacker and allows
the squid to quickly swim away and hide. Squid also have the ability to change their
color to match their background.
Questions:
12. How do squid capture their prey?
13. How do squid keep from being eaten?
Reproduction:
Squid have two different sexes. The male fertilizes the female’s eggs inside the mantle.
The eggs are encased in a gooey mass that hardens when it is released into the water.
Most squid lay one egg at a time. Young squid look like a smaller version of the adults.
Questions:
14. How many sexes do squid have?
15. Where does fertilization take place?
The Squid Dissection
Materials:
Dissecting scissors, Tweezers, dissecting tray and one squid
Procedure:
With your group do the dissection step by step as given in the directions. Answer the
questions as you go. Label the diagram at the end. When you have finished your
dissection, make sure throw away all parts of your squid, wash your trays and dissecting
equipment and return it dry.

Examine the outside structures of the squid, looking closely at the arms, head,
mantle and lateral fins.
Questions:
1. How many arms are there?
2. Do all the arms have suction cups? If not how many do not.
3. What is covering the mantle?