Category: 2nd Semester

Clam Dissection Questions

 

 

  Clam Dissection Questions

 

Pre-lab:
1. Give the kingdom, phylum, and class for the clam.

 

2. Describe the body of bivalves.

3. How do bivalves move?

4. Why are they called bivalves?

5. Is their digestive tract complete or incomplete?  Explain your answer.

 

6. Do bivalves show cephalization?  Explain your answer.

 

7. What are siphons & what is their purpose?

 

8. How can you distinguish a mussel from a clam?

 

9. Adults are usually sessile, but the larva or _________________ is free-swimming.

10. Are bivalves protostomes or deuterostomes?

11. Their body cavity is called the _____________ cavity.

12. Body organs make up the ___________ mass and are protected by the _____________ which secretes the ___________.

13. Is circulation open or closed?

14. Give several examples of bivalves.

Lab Questions:
1. What is the oldest part of a clam’s shell called and how can it be located?

 

2. What do the rings on the clam’s shell indicate?

3. Name the clam’s siphons.

4. What holds the two shells together?

5. What muscles open & close the clam?

6. Describe the inside lining of the shell.

7. What is the function of the tooth-like projections at the dorsal edge of the clam’s valves?

8. Where is the mantle located in the clam?  What is its function?

 

9. Describe the clam’s foot.

 

10. What is the mantle cavity?

 

11. How do clams breathe?

12. What helps direct water over the gills?

13. Where are the palps found and what is their function?

 

14. Describe the movement of food from the current siphon through the digestive system of the clam.

 

 

15. Where is the clam’s heart located?

 

16. What are the parts of the clam’s nervous system?

 

17. Why are clam’s referred to as “filter feeders”?

 

18. Label the internal structures of the clam and draw arrows showing the pathway of food as it travels to the clam’s stomach:

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Crayfish Dissection

 

Crayfish Dissection

 

Virtual Crayfish Dissection – Cornell Virtual Crayfish Dissection – Penn State
crayfish_mini1.gif (6395 bytes) bottom.jpg (95862 bytes)

 

 

By Day:    Day 1        Day 2        Day 3

By Region: External Anatomy    Internal Anatomy

By Topic:      Skeletal       Integumentary     Cardiovascular     Muscular    Endocrine    Nervous
Reproductive     Respiratory    Excretory    Digestive

 

You must create a series of labeled drawings that illustrate the structures outlined below:

Day 1

I. Abdomen – Ventral View          (Day 1)         top

Place the crayfish supine (ventral surface up) on the dissecting tray and DRAW the following:

 

  1. Telson (What is the telson’s function?)
  2. Uropod  (Describe the location of the Uropod to the telson.   How do the add to the telson’s function?)
  3. Anus (In which of the two structures above did you find the anus? 1 or 2 way digestive system?)
  4. Swimmerets -numbered in pairs, 1-5 w/ the 5th one the most posterior (What is their function, and how is it different from the telson’s function?)
  5. Is your Crayfish a male or a female (Note the anterior-most swimmeret.   In the male, its function is to guide the sperm toward the female during copulation; as such, it will be enlarged, and pointed anteriorly in the male.  In the female there is no difference between the swimmerets)?  (Describe the appearance of the crayfish’s swimmerets in your answer.)
  6. Walking Legs (How many are there?  In terms of this feature alone, is this organism closer to an insect, or an arachnid?)
  7. Chelipeds – some people like this meat the best . . . (What is their function?)

 

II. Head – Ventral View             (Day 1-2)         top

 

  1. Mandibles – 2 – hard & white  (What are they equivalent to in humans?  How is their action – think direction of movement – different from that of humans?)
  2. Maxilla – softer w/ jagged edges  (Given the difference in texture, how is their function different from that of the mandibles?)
  3. Maxillapeds, or “mouth-feet” -3 pairs  (What is their function?  Why not use the Chelipeds?)
  4. Green Gland Ducts – (From what organ do they open out?  What is the equivalent organ in humans? What is the purpose of the duct?  Is its location at all disturbing to you?)

  

 

II. Cephalothorax – Dorsal View             (Day 1-2)         top

  1. Rostrum (What is cephalization?  Given that, what organ would you expect to be inside the rostrum?)
  2. Eyes (Does this organism have binocular vision – depth perception, why or why not?)

     


    Eye

     

  3. Carapace (What is the function of the carapace?  What two body systems in humans perform equivalent functions?  The support function is in reference to one system in particular; given the external location of the carapace, explain the name of the type of system compared to our own, internal variety.  The support function implies specifically the attachment of organs of what body system to the inside of the carapace?

Day 2

Make a Dorsal Midline Incision from the posterior end of the thorax to the posterior end of the rostrum using the rounded scissors w/ the rounded end down! Open the carapace and pin it back.

III. Thorax – Dorsal View, Part I          (Day 2)         top

  1. Heart & Ostia – the opening on the heart’s superior surface (Is this a sign of an open or closed circulatory system?  Differentiate between the two in your answer.)
  2. Gills (What are they equivalent to in humans?  To what body system do they belong?  Why are the gills so feathery – i.e., how does this aid in their function?)
  3. Cardiac Stomach -draw whole (There appear to be fibers attached to the outside of the stomach.  What is their purpose in relation to the stomach and the esophagus?)

IV. Thorax – Dorsal View, Part II         (Day 2)         top

  1. Remove one gill and draw on high power (What is the red/pink material within each “finger” of each gill?  How does this material relate to the function of the gill?)
  2. GENTLY remove one walking leg, and you will see that a gill is attached to each walking leg.  (How is this important to the function of the gills?  In your answer refer to the different requirements of the body during times of high physical activity, and how they are related to the gill-walking leg connection.)
  3. Cut open the Cardiac Stomach and draw the Gastric Mill – reddish-brown lateral “teeth” – on high power  (What is their function?  What type of digestion involves the gastric mill?  Do we accomplish that type of digestion in our own stomach?)

Day 3

V. Thorax – Dorsal View, Part III         (Day 3)         top

Gently remove the Heart.

  1. The Intestine (Given its location posterior to the stomach, what is its function?  What function of the stomach is lacking in the intestine?)
  2. The Hepatopancreas Gland (What two organs is this equivalent to in humans?  What are some of the functions of this gland?  How is its location important to its function?)
  3. The Seminifierous Tubules or Ovaries  (What is the function of each? To what body system do these belong?  Which of the two does your specimen contain?  How is this related to the swimmerets?)

 

 

VI. Thorax – Dorsal View, Part IV         (Day 3)         top

Gently remove the Cardiac Stomach.

  1. Esophagus  (Describe how it’s position relative to the stomach is different from the worm and the human.)
  2. Green Gland (What is/are the equivalent organ(s) in humans?   Do/does the analogous organ(s) appear in pairs in humans?  To what body system do the green glands belong?  What organ in our equivalent body system is missing in the crayfish?)
  3. Brain (Describe the appearance of the brain and the nerves in terms of the type of symmetry.  There are nerves that are attached to the front and the back of the brain.  Describe the function of both the anterior and the posterior nerve pairs.)

VII. Abdomen – Dorsal View, Part I       (Day 3)        top

Make a Dorsal Midline Incision from the anterior end of the abdomen to the posterior end of the abdomen using the rounded scissors w/ the rounded end down! Open the exoskeleton and pin it back.

 

In order for a Crayfish to determine BALANCE, it must insert a grain of sand in one of it’s appendages.
Every time it molts and makes a new exoskeleton, it must get a new grain of sand!
(In what part of the body is that function taken up by the human body?)

 

  1. Dorsal Blood Vessel  (Is this vessel sending the blood to, or away from, the heart?  What name would we give to that type of vessel in our body?)
  2. Large Intestine (How is the location of this organ related to the name of this section of the body [it is NOT a tail]?  What is the function of the large intestine?  Given it’s contents, is it wise, or unwise, to eat it when eating a lobster?  Explain.)
  3. Abdominal Flexor Muscles  (How do muscles function, by shortening,   lengthening, of both?  Moving the abdominal flexor muscles will cause flexion, but what is flexion?  How will the abdomen – it is NOT a tail – change shape during flexion?  What direction will the crayfish move during flexion?  Given the size and strength of the muscle, during what circumstances would the crayfish use this muscle over its walking legs?)

VIII. Abdomen – Dorsal View, Part II        (Day 3)        top

Gently remove the Abdominal Flexor Muscles.

  1. Ventral Blood Vessels  (Given that there is no main ventral blood vessel, how does the blood return to the heart?  Is this a sign of an open or closed circulatory system?)
  2. Ventral Nerve Cord  (To what phylum does the crayfish belong?   How is the location of the nerve cord different from creatures in our own phylum?   Name our own nerve cord.  How is the protection of the nerve cord different in both phyla?)

Drawings:

  1. Use a PENCIL!!

  2. Make the drawings “larger than life” size, as the specimens are so small.

  3. Draw the general shape (outline) and location of the organs, as the squiggles so many of you use to “shade” your drawings make your drawings sloppy and hard to interpret.

  4. Include Labels on all drawings.

  • Labels should start outside the drawing, and be connected to the structure by arrows with tips (===>).

  • The Tip of the arrow should be touching the structure.

  • Be sure to include the magnification for any drawings done with the dissecting microscope.

Hang on to the drawings; they will all be handed in later, together with some questions to answer!


Day 1        Day 2        Day 3         top

Modified from  Lazaroff Biology

 

Crayfish Appendage Table

Crayfish Appendage Table

Appendage Function Location Attach Appendage Here
Antennules Senses touch & taste; helps crayfish maintain balance in front of the mouth .
Antenna Senses touch and taste in front of the mouth .
Mandible or jaw Crushes food mouth .
First Maxilla Moves food to the mouth behind the mandibles .
second maxilla moves water in the gill chamber behind the mandibles .
First maxilliped Holds food; Senses touch and taste at ventral and forward part of the thorax region .
Second maxilliped Holds food; Senses touch and taste at ventral and forward part of the thorax region .
Third maxilliped Holds food; Senses touch and taste at ventral and forward part of the thorax region .
Cheliped Grasps food at ventral part of thorax-posterior to the maxillipeds .
walking leg locomotion at ventral part of thorax-posterior to the maxillipeds .
Swimmeret 1st swimmeret in males transfers sperm to female; females use the 2nd-5th swimmerets to hold eggs & young; locomotion abdominal region on the ventral side .
uropod swimming posterior or tail end .
telson swimming posterior or tail end .

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Crayfish Dissection

 

Crayfish Dissection
Objectives:
• Describe the appearance of various organs found in a crayfish.
• Name the organs that make up systems of the crayfish.

 

Materials:
• safety goggles, gloves, magnifying glass, a lab apron, plastic zip lock bag preserved crayfish,  pen, dissecting tray, paper towels, scissors, forceps, dissecting needle, and dissecting pins.

 

Purpose:
In this lab, you will observe the external structures of a crayfish and dissect it to study its internal structures and systems.

 

Background:
Like all crustaceans, a crayfish has a fairly hard exoskeleton that covers its body. As shown in the diagram on the next page, its body is divided into two main parts, the cephalothorax and the abdomen. The cephalothorax consists of the cephalic (or head) region and the thoracic region. The part of the exoskeleton that covers the cephalothorax is called the carapace. The abdomen is located behind the cephalothorax and consists of six clearly divided segments. The cephalothorax consists of 13 segments. Each segment of both the cephalothorax and the abdomen contains a pair of appendages. The head (or cephalic) region has five pairs of appendages. The antennules are organs of balance, touch, and taste. Long antennae are organs for touch, taste, and smell. The mandibles, or jaws, crush food by moving from side to side. Two pairs of maxillae hold solid food, tear it, and pass it to the mouth. The second pair of maxillae also helps to draw water over the gills. Of the eight pairs of appendages on the cephalothorax, the first three are maxillipeds, which hold food during eating. The chelipeds are the large claws that the crayfish uses for defense and to capture prey. Each of the four remaining segments contains a pair of walking legs. In the abdomen, the first five segments each have a pair of swimmerets, which create water currents and function in reproduction. The sixth segment contains a modified pair of uropods. In the middle of the uropods is a structure called the telson, which bears the anus. The uropod and telson together make up the tail fan. The crayfish moves backward by forcing water forward with its  tail fan.

Procedure Part 1—External Anatomy of a Crayfish

1. Put on safety goggles, gloves, and a lab apron.

 

2. Place a crayfish on its side in a dissection tray. Use the diagram below to locate the cephalothorax and the abdomen. The carapace, a shield of chitin, covers the dorsal surface of the cephalothorax. On the carapace, observe an indentation, the cervical groove, that extends across the midregion and separates the head and thoracic regions. On the thoracic region, locate the prominent suture or indentation on the cephalothorax that defines a central area separate from the sides. Note the individual segments of the abdomen.

 

What is the main difference between the cephalothorax and abdomen?

___________________________________________________________

3. Turn the crayfish with its DORSAL side upward, and locate the rostrum, which is the pointed extension of the carapace at the head of the animal shown in the diagram above. Beneath the rostrum locate the two eyes. Notice that each eye is at the end of a stalk.

4. Locate the five pairs of appendages on the head region. First locate the antennules in the most anterior segment. Behind them observe the much longer pair of antennae.

Why is it useful to view the specimen on its Dorsal side for this part of your study?
______________________________________________________________

5. Locate the mouth. Then observe the mandibles, or true jaws, behind the antennae. Now locate the two pairs of maxillae, which are the last appendages in the cephalic region.

Which appendages in the cephalic region are related to the eating of food?
_____________________________________________________________

 

6. On the thoracic portion of the cephalothorax, observe the three pointed maxillipeds.

How are the maxillipeds related to eating?
______________________________________________________________

 

7. Next observe the largest prominent pair of appendages, the chelipeds, or claws. Behind the chelipeds locate the four pairs of walking legs, one pair on each segment.

 

8. Now use the walking legs to determine the sex of your specimen. Locate the base  segment of each pair of walking legs. The base segment is where the leg attaches to the body. Use a magnifying glass to study the inside surface of the base segment of the third pair of walking legs. If you observe a crescent-shaped slit, you have located a genital pore of a female. In a male, the sperm duct openings are on the base segment of the fourth pair of walking legs. Use a magnifying glass to observe the opening of a  genital pore.

 

Is your specimen a male or a female?
_____________________________________________________________

Exchange your specimen with a nearby classmate who has a crayfish of the opposite sex. Then study its genital pores.

 

9. On the abdomen, observe the six distinct segments. On each of the first five segments, observe a pair of swimmerets.

10. On the last abdominal segment, observe a pair of pointed appendages modified into a pair of uropods. In the middle of the uropods, locate the triangular-shaped telson.

 

11. Now turn the crayfish ventral side up. Observe the location of each pair of appendages from the ventral side.

From which view, dorsal or ventral, can you see the location of the appendages on the segments more clearly?
______________________________________________________________

12. Remove all jointed appendages of the crayfish and attach them to the table on the crayfish worksheet.

If dissection is two day, complete steps 13 and 14 only!

 

13. Next you will study the internal anatomy of a crayfish. If you must store your specimen until the next lab period, cover it with a dampened paper towel. Then place the specimen on the tray in a plastic bag. Close the bag with a twist tie. Write your name on the bag with a felt-tip marking pen, and give your specimen to your teacher.

 

14. Clean up your work area and wash your hands before leaving the lab.

 

Part 2—Internal Anatomy of a Crayfish

15. Put on a lab apron, gloves, and safety goggles.

 

16. Using one hand to hold the crayfish dorsal side up in the dissecting tray, use scissors to carefully cut through the back of the carapace along dissection cut line 1,  as shown in the diagram below. Cut along the indentations that separate the thoracic portion of the carapace into three regions. Start the cut at the posterior edges of the carapace, and extend it along both sides in the cephalic region.

 

 

17. Use forceps to carefully lift away the carapace. Be careful not to pull the carapace away too quickly. Such action would disturb or tear the underlying structures.

18. Place the specimen on its side, with the head facing left, as shown in the diagram below. Using scissors, start cutting at the base of cut line 1. Cut along the side of the crayfish, as illustrated by cut line 2. Extend the cut line forward toward the rostrum (at the top of the head).

 

19. Use forceps to carefully lift away the remaining parts of the carapace, exposing the underlying gills and other organs.

 

20. Use the diagram below to locate and identify the organs of the digestive system. Locate the maxillae that pass the pieces of food into the mouth. The food travels down the short esophagus into the stomach. Locate the digestive gland, which produces digestive substances and from which the absorption of nutrients occurs. Undigested material passes into the intestine. Observe that the intestine is attached to the lobed stomach. The undigested material is eliminated from the anus.

Rows of chitinous teeth line the stomach. Predict their function.
_____________________________________________________________

 

21. Use the diagram below to locate and identify the organs of the respiratory system. Locate the gills, which are featherlike structures found underneath the carapace and attached to the chelipeds and walking legs. A constant flow of blood to the gills releases carbon dioxide and picks up oxygen.

The feathery nature of the gills gives them a very large surface area. Why is this important?
____________________________________________________________

 

22. Use the diagram of the internal anatomy of the crayfish to locate and identify the organs of the circulatory system. Locate the dorsal tubular heart and several arteries. The crayfish has an open circulatory system in which the blood flows from arteries into sinuses, or spaces, in tissues. The blood flows over the gills before returning to the heart.

 

23. Use the same diagram to locate and identify the organs of the nervous system. Find the ventral nerve cord. Locate a ganglion, one of the enlargements of the ventral nerve cord. Locate the dorsal brain, which is located just behind the compound eyes. Note the two large nerves that lead from the brain, around the esophagus, and join the ventral nerve cord.

Many nerves leave from each ganglion. Where do you think these nerves go?
__________________________________________________________

 

24. Use the same diagram to locate and identify the organs of the excretory system. The blood carries cellular wastes to the disk-like green glands. Locate these organs just in front of the stomach. The green glands excrete waste through pores at the base of each antenna.

What organs in your body carry out the same function as the green glands?

      ____________________________________________________________

 

25. Use the diagram once again to locate and identify the organs of the reproductive system. The animal shown in the diagram is a male crayfish. If your specimen is a male, locate the testis. The testis is the long, white organ under the heart and a bit forward. The sperm ducts that carry sperm from the testis open at the fifth walking leg. If your specimen is a female, locate the bi-lobed ovary. It is in the same relative position as the testis, but the ovary appears as a large, reddish mass under the heart. Then locate the short oviducts that extend from near the center of each side of the ovary and open at the third walking leg. Exchange your specimen with a nearby classmate who has a crayfish of the opposite sex. Then study its reproductive system.

25. Dispose of your materials according to the directions from your teacher.

 

26. Clean up your work area and wash your hands before leaving lab.

Crayfish Worksheet Crayfish Appendage Table

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Classification Bi Worksheet

 

Classification

 

Section 18-1            History of Taxonomy 

1. Define taxonomy. 

2. Who was first to classify organisms? 

3. Explain Aristotle’s taxonomy of organisms. 

4. Why are common names not good to use when classifying organisms? Give an example. 

5. Describe Carolus Linnaeus’s system of classification. 

6. Linnaeus used ____________________ or form & structure to classify organisms. 

7. List Linnaeus’s levels of organization in order starting with the broadest classification level. 

8. Name Linnaeus’s two kingdoms. 

9. What is the difference between phylum & division? How are they alike?

10. What classification level contains only a single type of organism? 

11. Give the taxonomy for a lion. 

12. In Linnaeus’s naming system, ___________________ words are used as the name. 

13. Explain Linnaeus’s 2-word naming system. 

14. What is Linnaeus’s naming system called? 

15. Write the scientific name for man. 

16. The ___________ name is written first and must always be __________________. 

17. The ____________ name is written second and should _____________ be capitalized. 

18. Name 2 things a species name may do. 

19. What are varieties? 

20. What are subspecies? 

21. Write a scientific name that includes a subspecies. 

22. What do modern taxonomist use to classify organisms? 

23. What is phylogeny? 

Section 18-2            Modern Phylogenetic Taxonomy 

24. Name 6 things used by modern taxonomists to classify organisms. 

25. Classification of an organism should reflect its __________ or ___________ history.

26. What is systematics?

27. Name a tool used by systematic taxonomists.

28. What is a phylogenetic tree? 

29. Draw a phylogenetic tree showing the possible relationships among animal phyla. 

30. Do phylogenetic trees ever change?  Explain. 

31. What complex animal group is located at the top of your phylogenetic tree? 

32. Do all organisms have complete fossil records? Explain. 

33. Which structures show that organisms are more closely related, homologous or analogous? 

34. Features similar in structure but with different functions are called _______________ structures.

35. Early patterns of similar ______________________ development show relationships. 

36. The fertilized egg or _______________ divides by mitosis. 

37. What is the blastula & make a sketch? 

38. What is the blastopore, & what does it become? 

39. The blastopore becomes the mouth in many animals except in ________ where it becomes their ______________.

40. What invertebrate group is most closely related to the vertebrates? 

41. Taxonomists compare macromolecules such as ____________, ____________, & ____________ to show similarities among species. 

42. If two organisms have similar banding patterns on their chromosomes then they are _______________ related.

43. What is used in cladistics to show evolutionary relationships? 

44. What is a derived character & give an example? 

45. Do shared derived characters show common ancestry?

46. What is a cladogram? 

47. Sketch a cladogram for vertebrates. 

Section 18-3            Modern Systems of Classification 

48. The discovery of 2 broad types of bacteria led taxonomists to develop what type of classification system? 

49. Name the 6 kingdoms & tell which are prokaryotes & which are eukaryotes. 

50. Describe members of the kingdom Archaebacteria. 

51. In what type of environment are Archaebacteria found? 

52. Did Archaebacteria carry on photosynthesis? 

53. What kingdom contains true bacteria? 

54. Name 4 things Eubacteria do that affect your life.

55. Do all true bacteria use oxygen? Explain. 

56. How do all bacteria reproduce? 

57. Why are bacteria able to evolve so quickly? Give an example. 

58. Most protists are ______ organisms, but some like the giant kelp are _________ without __________. 

59. Since protists are eukaryotes, what special structures do they contain? 

60. Some protists like ________________ feed on other organisms, while __________ have chloroplasts & make their own food.

61. Describe the characteristics of fungi. 

62. How do fungi get food? 

64. Multicellular plants are in the ____________________ kingdom. 

65. Most plants are ________________ and make food energy by ________________. 

66. Most plants live on ________________. 

67. Name 4 examples of major plant groups. 

68. Describe the characteristics of the animal kingdom. 

69. Most animals have _______________ body organization. 

70. Both plants & animals reproduce ________________. 

71. Using information about __________ RNA, __________ developed the three _______ classification system. 

72. Name the 3 domains. 

73. Domain ___________ contains the same organisms as the kingdom Archaebacteria. 

74. Domain ________________ contains the same organisms as kingdom Eubacteria. 

75. What is included in domain Eukarya? 

76. What characteristic do all members of the domain Eukarya have in common with each other

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