Squid Lab Dissection

7/24/2019 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

Squid Lab Dissection

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