Identifying the Squid:
First, the students identified and documented all the parts of the squid. The students then counted the arms and tentacles. They also had already drawn pictures of the squid and answered questions relating to the squid's exterior anatomy.
Dissecting:
Depending upon the student, this step was either fun or disgusting. The students proceeded to cut open the squid and identified the internal organs. Next, they determined whether the squid was a male or a female. Then the students wrote their names with squid's pen and ink on their drawings.
Learn More About Squid:
The squid is one of the most highly developed invertebrates. Some of the animal's
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 squeezes
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.
Squid Parts:
CHROMATOPHORES
These spots change size
to change the squid's color
for camouflage or possibly
communication.
FIN
These help squid
change direction
when swimming. MANTLE
This is the main part of the
squid's body--all the organs
are inside.
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.
EYE
Squids have a well
developed eye that
allows them to see
about as well as people!
ARM
Squid have 8
arms covered
suction cups.
SUCTION CUPS
The suction cups help the
squid to hold onto food.
TENTACLE
The tentacles are longer
than the arms and have
suction cups only at the tips.
These are used to pass food
to the shorter arms and then
to the mouth.
From Pen to Ink
