Squid Dissection - Jasmin Lidder 1 6l1j5w

MARINE BIOLOGY SQUID DISSECTION LAB

INTRODUCTION:

Adapted by Anne Maben from HMSS ​Living Ocean text

Name: Jasmin Lidder Partners: Jasmeen Padda, Siman Grewal

The cephalopods include squid, octopus, cuttlefish, and nautilus. The class name, ​CEPHALOPODA ​ , meaning "head-foot," aptly describes this group. The foot in this group has specialized by dividing ​ into ​arms, which are attached to the head. Most cephalopods do not have external shells. The squid has an internal remnant of a shell, called ​ a ​pen, that looks like a sheet of thick plastic. This long, thin shell helps the body. The cuttlefish, a close relative of the squid, has a harder, more brittle plate, called a​ ​cuttlebone. A cuttlebone is made of calcium carbonate (CaCO3) secreted by the animal; in composition it is similar to the shells of other mollusks. Gas moving in and out of chambers in the cuttlebone lets the cuttlefish move up and down in the water. Cuttlebones are often put in bird cages for the bird to peck on, sharpen its beak, and eat the calcium, a necessary nutrient.

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In the mouth of the squid ​ is a ​beak shaped much like the beak of a parrot. The beak is not part of the shell but a separate tooth-like structure. When a squid catches prey, such as a fish, it bites off and swallows chunks of it. The squid has ​ a small ​radula but it uses it only to pull in chunks of food past the beak. Cephalopods are also masters of camouflage, using pigment in their skin cells to quickly change its skin color to blend into its surroundings. These skin cells, called ​chromatophores, contain an elastic sac filled with pigment. The cells are attached to a set of muscle cells. When the muscle cells contract, they pull the chromatophore out flat, spreading the pigment over a larger area and making the skin darker. When the chromatophore is smaller, the skin is lighter. The cells can change shape very rapidly, producing a pulsating patterns of complex color changes. Cephalopods use chromatophores to communicate their moods to others - bright red for anger or ion; white for fear. Pelagic squid even have bioluminescent chromatophore on their ventral side, which they can change the light intensity of to ​Α​match​≅​ ​the light from the ocean​=s​ surface (making them invisible to predators below.) The highly intelligent cuttlefish appear to use chromatophores as a ​Α​visual language​≅​ ​between their fellows, a language humans have yet to decipher.

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In cephalopods, the primary swimming organ is the muscular mantle, which forms a chamber that opens to take in seawater. When the mantle closes forcefully, seawater ejected through the ​siphon jet-propels the animal in short bursts. Squids and cuttlefish change course by quickly redirecting their siphon. They steer by pressing their arms together. They can speedily elude an attacking predator. They can also squirt ink from the ​ink sac into the water, creating an ink cloud for camouflage and confusing the predator. The squid an cuttlefish can also wave their paddle-shaped ​fins to move slowly forward or backward. The fins also aid the squid in steering and in stabilizing their movements.

Most cephalopods are relatively small. The giant squid, the largest of invertebrates, reaches lengths of 15 m. It is the favorite prey of sperm whales and the basis for many myths about sea monsters.

MATERIALS fresh or defrosted squid wax paper dissecting scissors dissecting tray blunt probe microscope slide dissecting microscope

PROCEDURE 1.

Lay the squid dorsal side down on a piece of wax paper laid a dissecting tray. Lay the squid with its head to the left and its siphon up. See Fig. 6-13.

2.

Reach under the animal and remove the pen from the dorsal side by grasping it firmly with your fingers and pulling it free from the mantle.

3.

Using a scalpel or dissecting scissors, cut the mantle from its anterior edge next to the siphon to its posterior tip. Do not cut into the internal organs.

4. Using a blunt probe, find these structures and describe their functions. Refer Fig. 6 -14 as needed. a. caecum f. ovary or testis b. intestine g. gills c. pen h. chromatophores d. ink sac I. kidney e. heart j. nidamental gland

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5.

Examine a single sucker from an arm. a. Cut off a O.5-cm piece of the arm and place it on a glass slide. b. View it under the dissecting microscope. c. Draw a picture of it in the Discussion section.

6.

Observe the chromatophores, small freckle-like spots on the outer layer of the mantle. Cut out or peel off a small piece of the skin that contains the spots. Ob serve at about 2OX under a dissecting microscope. Stretch the skin, noting any apparent change of color. Record your observations.

7.

Remove the beak. a. Cut the arms from the head with scissors at line (A) as shown in Fig. 6-15 b. Push out the beak. Wash it and save it. Draw a picture of it in the Discussion section. c. Remove the internal organs and wrap them in a plastic bag or newspaper. Give them to your teacher or save them for feeding aquarium organisms.

Name: Jasmin Lidder

Date: May 10, 2018

Period: ABCD

Group: Jasmeen Padda, Siman Grewal

DISCUSSION: STRUCTURE

caecum ovary or testis intestine

FUNCTION

Receives digested food from the stomach and absorbs it into the bloodstream for further use. Used to reproduce (females have an ovary to produce eggs, testis used to produce sperm). Receives digested food from the caecum and supplies the nutrients to the blood.

Respiratory organs that exchange oxygen and carbon dioxide between the blood and sea water. Found within the mantle on the dorsal side (remnants of the shell), functions as a for pen the mantle. Bags filled with different pigments that allow the squid to change the colour of their skin to chromatophores camouflage themselves/blend into the environment. Organ that stores a black substance (ink) that serves to deceive potential predators and allow ink sac escape from predators. Used to remove waste products from the blood. kidney gills

systemic heart brachial heart nidamental gland (​>​) beak siphon fins retractor muscles brain optic nerve

1.

Heart that is larger than the other two hearts and is located between the branchial hearts, receives blood from the branchial hearts and pumps it throughout the body. Two hearts that are located at the base of the gill to pump blood from the body to the gills Secretes the gelatinous matrix that surrounds the squid eggs, hardens the eggs before being released. Used to tear food into small pieces, attached the the esophagus. Small tube on the ventral side of a squid/octopus that can be directed in any direction for jet propulsion Extension of the mantle used to guide and steer during swimming and to change speed when swimming. Allow the squid to move, direct, and create streams of water through its funnel. Highly developed organ that controls the squid’s actions. Used to tell the difference between light and dark, can also be used to see a complete image of what it is looking at

What are the distinguishing features of cephalopods?

All cephalopods have 3 hearts - two of which move blood to the gills, and the other one pumps blood to the rest of the body. They also have blue blood due to the binding of oxygen with the protein hemocyanin. Cephalopods have much larger and more developed brains than other invertebrates. They also have chromatophores which allow them to change colour quickly to escape predators and hide. They can even make intricate patterns and shapes on their skin. Lastly, all cephalopods have at least 8 arms. 2.

What features relate cephalopods to other mollusks?

Both cephalopods and mollusks have an unsegmented soft body, a mantle, a mantle cavity, and radula. 3.

What advantages do cephalopods get from their chromatophores?

Chromatophores are sacks of pigment that allow cephalopods to change the colour of their skin rapidly to escape/hide from predators using camouflage. It is also used as a part of mating rituals (males use their colours to try to impress females). 4

Describe jet propulsion and control of direction in a squid.

To travel by jet propulsion, a squid fills its muscular mantle cavity with water and then quickly expels the water out of a small tube (the siphon). The force of water coming out of the siphon opposes the equal amount of force of the squid’s body. The two opposing, equal forces allow the squid to jet away from its water stream. By pointing the siphon in different directions and by changing the amount of water drawn in, the squid can modify its direction and speed. 5. Describe several methods of escape (defense mechanisms) used by cephalopods.

Cephalopods can camouflage by using their ink to create ink clouds to escape predators. They can also change the colour of their skin to blend into their surrounds and hide. As well, they can use shells to protect themselves from predators. Lastly, they can use jet propulsion to rapidly escape predators.

Pictures:

Before

After

Conclusion: Through this dissection, we were able to discover that the dissected squid was a male (due to the absence of eggs). As well, we were able to find the ink sac which is a vital part of protection for them. We were also able to find the pen, hearts, lungs, and brain. Lastly, we were able to take the lens off the eyes. In conclusion, we were able to see a variety of functions of the squid through the dissection.