Download - Squid Lab Dissection
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Squid:
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Virtual Squid Dissection
This page can be used as a substitute for a hands-on squid dissection.Students without access to squid, or who were absent the day of the
dissection can view photos of the squid and complete the lab guide.
Step 1: Examine the External Anatomy of the Squid
Squids are shipped in bags and are stored in a preservative, when you firstopen the bag, you might notice a pungent aroma. Rinse the squid off andlay it in a dissecting pan.
Determine the dorsal (back) side of the squid by looking for a darkercoloration and the presence of fins.
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The eyes are quite large for an invertebrate and lie on either side of thehead. Note the mantle that surrounds the main part of the body. The squidhas two main parts: the mantle (with the fin) and the head region that alsocontains the tentacles (foot). In fact, that is why they are calledCEPHALOPODS, the word translates to mean "head-foot."
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Stretch the arms out so that you can count them and locate the two longertentacles. How many arms are visible?
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Each arm and tentacle comes equipped with suckers to help them latchonto and hold prey.
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The ventral side of the squid is lighter in color and the water jet is clearlyvisible from this angle.
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The mouth is found in the center of the arms. Pull the arms apart so thatthe mouth can be located.
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With a probe, you can feel the hard structure inside the mouth known asthe beak. The beak is used to tear prey and can be very sharp (and deadlyto fish!). To remove the beak, you probably will need to also remove themuscular bulb that surrounds it, known as the buccal bulb. The buccal bulb(or mass) can be removed by cutting at the base of the tentacles where themouth is located.
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In the photo below, the bulb has been removed and you can see the sharpbeak within it.
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In the following photos, you can see the buccal mass attached to a longtube. That tube is the esophagus. Cutting through the muscle of the buccalbulb will reveal two jaws. The jaws are also called the BEAK because itresembles the beak of a bird. This structure is sharp and strong and is usedto tear prey, such as fish.
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Part 2: Internal Anatomy of the Squid
Scissors are the best tool to open the squid's body cavity. You can easilyraise the mantle just where the water jet is located and cut to the anteriorend of the squid (toward the fins). The photo below shows the mantle of thesquid cut, but has not been pinned. The mantle is rubbery and will not stayopen unless you pin it open.
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Pin the mantle open so that the inside of the squid can be viewed. You maysee eggs if you have a female.
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One of the more obvious structures in the squid is the ink sac. It is visibleas a dark structure in the middle of the body cavity near the water jet.
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The feathery structures that lie on either side of the body cavity are thegills, at the base of each you find a heart, or more accurately called the gill-heart.
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The large structure in the middle of the squid is called the nidamentalgland. It is more noticeable in female squids.
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If you lift the nidamental gland, the stomach lies just underneath it. The
stomach is often a thin membraned structure that can easily be missedamong the other organs of the squid.
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At the water jet, are long structures that are used for movement - the
retractor muscles.
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If you push all of the organs of the coelom to the side, you can locate andremove the PEN of the squid. The pen is a hard structure that is used tostabilize the squid when its swimming. If you are careful, you can remove itin one piece.
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These are pens that have been successfully removed.
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Part 3 - Clean Up
The squid is often a messy dissection, trays are lined with paper towels tohelp with the cleanup process. Since a virtual lab skips the messy part,consider a mental clean-up of the structures you need to know. Studentswere also required to label the squid. Print out theSquid DissectionGuideand make a sketch of the external anatomy and label the internalanatomy of the squid.
http://www.biologycorner.com/worksheets/squid_dissection.htmlhttp://www.biologycorner.com/worksheets/squid_dissection.htmlhttp://www.biologycorner.com/worksheets/squid_dissection.htmlhttp://www.biologycorner.com/worksheets/squid_dissection.htmlhttp://www.biologycorner.com/worksheets/squid_dissection.htmlhttp://www.biologycorner.com/worksheets/squid_dissection.html -
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SQUID VASCULAR SYSTEM
Ctenidia: -
A ctenidium is a respiratory organ orgill which is found in many molluscs. A ctenidium is shaped like
a comb or a feather, with a central part from which many filaments or plate-like structures protrude,
lined up in a row. It hangs into themantle cavity and increases the area available for gas exchange.
Branchial hearts: -
A muscular enlargement of a vein of a cephalopod that contracts and drives the blood into the gills.
Anterior (or cephalic) vein: -
Large vein that drains the head and lies on the ventral surface of the visceral sac, along side or dorsal
to the intestine. The cephalic vein terminates by dividing into the two vena cavae, each of which
passes through the "kidney" (nephridium), the branchial heart and into the gill.
Anterior (or cephalic) artery: -
Blood is then pumped from the systemic heart to the body via the main cephalic artery.
Heart: -
Branchial heart- A pulsating gland at the base of the gill and through which the afferent blood to
the gills flows. It contributes to the blood flow through the gill but also is the site of hemocyanin (the
blood respiratory pigment) synthesis.
Ink sac: -
Ink sac- Organ composed of a gland that secretes ink, a sac that stores ink and a duct that connects
it to the rectum. The ink sac generally appears black from the outside although it may be covered by
silvery tissue in some species.
https://en.wikipedia.org/wiki/Gillhttps://en.wikipedia.org/wiki/Mantle_cavityhttps://en.wikipedia.org/wiki/Mantle_cavityhttps://en.wikipedia.org/wiki/Gill -
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Reproductive System:
Female:
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MalGill
Penis with spermatophores
Gill
Penis with
spermatophores
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Funnel or siphon Funnel retractor muscle Gill Penis Sp
Gill or branchial heartGillRectum Systemic heart
Male Squid
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Male Squid
Spermatophores Sperm duct
Branchialheart
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Female
Ovary with eggs Nidamental Gland
Funnel retractor muscle FunnChromatophores (Pigment cells)
GillCecum
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ENidamental glandAccessory
nidamental gland
Female
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Gill (Branchial) Heart
Gill (Branchial) HeartSyste
Heart
Medial mantle artery
Lateral
Mantle
Artery
Male Squid
Caudal AortaTestis
Gill
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Cecum
Testis Penis
Gill
Gill
Systemic
Heart
Gill (Branchial)
Heart
Gill
Heart
Caudal
Aorta
Medial
Mantle
ArteryFunnel or Siphon
Ste
M
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A.
B.C.
D.
E. F.
G. H. I. J. K.
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Answers
A. Cecum
B. Lateral mantle artery
C. Medial mantle artery
D. Gill (Branchial) heart
E. Systemic heart
F. Gill
G. Testis
H. Caudal aorta
I. Penis
J. Stellate ganglion
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1. 2. 3. 4. 5.
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Answers
1. Funnel or siphon2. Funnel retractor muscle
3. Gill
4. Nidamental gland
5. Ovary
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Left gill (branchial) heart p
blood to the gills
Afferent gill blood vess
low O2blood to from gil
gills.
Efferent gill blood ve
high O2blood to syst
Systemic
heart
Caudal
aorta
Right
ateral
mantle
artery
Gill
Note that I removed the
right gill (branchial) heart
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Left gill (
Syste
Caudal
aorta
Lateral
mantle
artery
Gill
Note that I r
right gill (bra
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Right lateral
mantle arteryCaudal aorta Systemic heart
Left lateral
mantle artery
Left gill (branchial) heart
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Gill Left lateral mantle artery
Systemic heart
Caudal aorta
Right lateral
mantle artery
1. 2.
3.
4.
5.
6.
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Answers
1. Systemic heart2. Caudal aorta
3. Right lateral mantle artery
4. Left lateral mantle artery
5. Gill (branchial) heart
6. Gill
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Annotations:
Testis:
Males do not possess these organs, but instead have a largetestis in place of the ovary, and a
spermatophoric gland and sac. In mature males, this sac may containspermatophores,which are
placed inside the female's mantle during mating.
https://en.wikipedia.org/wiki/Testishttps://en.wikipedia.org/wiki/Spermatophorehttps://en.wikipedia.org/wiki/Spermatophorehttps://en.wikipedia.org/wiki/Testis