Diseccion De Tiburon

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Shark Dissection – Dogfish
Squalus acanthias
Fun Facts:
• The teeth of sharks are modified scales embedded in the skin of its mouth
• Sharks have pits on their face used to detect electric fields
• Sharks have paired fins that are homologous to your arms and legs
• The skeleton of a shark is made entirely of cartilage
• Sharks have gills located in pouches alongthe sides of their heads
• A shark's heart pumps blood directly through its gills before the blood flows to the rest of its body
• The liver of a shark is its largest internal organ and is very oily
Materials:
• A dissecting pan layered with wet paper towels
• Dissecting tools (scalpel, scissors, probe, forceps)
• Your textbook and lab manual (Lab manual pp. 230, 263, 267– shark brain, 232 –heart, 233, 276 – branchial arteries, 290, 291 – gills and respiration, 319, 320 – reproduction) (Textbook pp. 362 – shark skin, 387 – brain, 396 – nervous, 412, 413 – endocrine, 430 – circulatory, 436 – gills, 454 – digestion, 467, 468 – thermoregulation, 477 - osmoregulation
• Sheet of paper
The External Anatomy:
1. Obtain a dogfish shark and record the followingdata:
____________________________________ ___________________________________
Common name Scientific name
Length overall _______________________________________cm.
Fork Length _________________________________________cm.
Width at head ________________________________________cm.
Width at posterior (side awayfrom head) to pectoral fins _________________________ cm.
Width at beginning of caudal fin _________________________cm.
2. On your sheet of paper sketch the shape of the fins listed and tell what their function is.
a. 1st dorsal fin
b. Pectoral fin
c. Pelvic fin
d. 2nd dorsal fin
e. Caudal fin
f. Anal fin
The External Anatomy:
1. On your sheet of paper make aside view sketch of your dogfish and label it "Side View".


2. The shark has a graceful and streamlined body shape. Given this body shape, what would you expect its lifestyle to be?

3. The body is divided into the head, trunk, and tail. Label each of these sections.


4. Underneath your sketch make some specific observations (at least 5) about the shark’s appearance, texture,and color. What is the purpose of the shark’s coloration? What is the name for this type of coloration?

5. Label the lateral line on your sketch. What is it and what function does it perform for the shark? Use the overall length of your shark to determine the percentage of the total length occupied. (Hint: % of body length occupied by lateral line = length of lateral line X 100overall body length

6. Label the anterior dorsal fin and posterior dorsal fin. What do you think the dorsal fins do? How do they compare?

7. Note the spines that are located directly in front of the fins. These spines carry a poison secreted by glands at their base. Label these onyour sketch.


8. Locate the caudal fin on your shark. It is divided into two lobes: a larger dorsal lobe and a smaller ventral lobe. This type of tail is known as a heterocercal tail. Label the caudal fin on your sketch. What is its purpose?

9. The rostrum is the pointed snout at the anterior end. Label it on your sketch. What purpose might its pointy-ness serve?

10. The eyesare prominent in sharks and are very similar to the eyes of man. A transparent cornea covers and protects the eye. A darkly pigmented iris can be seen below the cornea with the pupil at its center. Upper and lower eyelids protect the eye. Just inside the lower lid is a membrane that extends over the surface of the eye to cover the cornea. Label your eye.

11. Find the two large openings...