Topic 3: Elasmobranch Anatomy 2 Flashcards
(111 cards)
What topics are covered in this section?(3)
- Muscle System
- Internal Organs
- Nervous System
Muscle Anatomy:
Sharks are comprised of about _% muscle tissue whereas humans are 35%.
85%
Muscle Anatomy:
- Most sharks are comprised of white muscle fibres up to _%.
90%
Muscle Anatomy:
- Function of white muscle?(vs red)
- burst activity
- less stamina
- Different physiological makeup vs red muscle
L> less mitochondria
L> less oxygen binding myoglobin
***aka rapid speed but not for long duration = white muscle
Muscle Anatomy:
-Lamnid sharks and a few other sharks, possess a band of what?
- Dark red muscle that runs along the flanks just under the skin
Muscle Anatomy:
- Red muscle has substantially greater __ than white. Give some characteristics.
- stamina
- more oxygen binding = red
- more mitochondria
- heat generation
**mostly runs in the core of the animal
L> core temp in here = 77 –> keeps organs warm
L> outer band of muscle matches the outside water temp
Muscle Anatomy:
- From opportunistic dissections of Porbeagle, Salmon, Shortfin mako, and white sharks, researchers have noted that the length of this band of dark muscle what?
- varies greatly among the various genera
L> variation in length of red muscle band…which conveys different swimming abilities
Muscle Anatomy: -Describe the differences in red muscle length etc in the following sharks : A. Salmon shark B. Mako C. Thrasher GW?
- All: bodies are stiffer!
L> short length of red muscle band= more stiff
Salmon>Mako>thresher (longest band) - Thresher is the most flexible of the three….its tail is very flexible and powerful bc of red muscle in the tail!
- swim with rigid body
*more energy efficient - GW: has a longer red muscle band than salmon and mako…almost to casual bedunkle
Muscle Anatomy:
- Studies indicate that as ___ increases ____ red muscle mass also increases.
- body mass increases
Muscle Anatomy:
- Porbeagle and salmon sharks (genus Lamna) typically have a very long/short band of muscle along their flanks.
- short
* * Shortfin makos are somewhat longer and those of the white shark (Carcharodon) are the longest of all
Muscle Anatomy:
- Given red muscles stamina, the White Shark’s less stiff bodied swimming style compared wit other laminas may be due to what fact?
- that it has the most extensive band of red muscle along its flank
Muscle Anatomy:
- Short red muscle = what?
- more stiff body but the swimming style is faster because they do not lose much energy and it is focused in the tail! BUT longer red muscle = more flexible
Muscle Anatomy:
- This marriage between muscle form and swimming function may result in significant what?
- advantages to the white shark
Muscle Anatomy:
- White Sharks:
- If the benefits of stiff bodied swimming comes at the cost of reduced maneuverability the development of what may partially off set that balance?
- the development of a more sinuous propulsive stroke (not that flexible but has a lot of force! )
- As such the white shark may be more maneuverable than its lamnid cousins
Muscle Anatomy:
- The ability to develop a more sinuous propulsive stroke may lead to what advantages?
- predatory advantages when pursuing swift and agile prey such as seals and sea lions
Muscle Anatomy:
- The ability to develop a more sinuous propulsive stroke may lead to predatory advantages when pursuing swift and agile prey such as seals and sea lions. If this is true than the great white has struck a highly what?
- beneficial compromise between the limitations of its body form and the adaptability of its red muscle band.
Muscle Anatomy:
- Shark swimming muscles like those of most fishes are composed of what?
- W shaped blocks called myotomes
L> interlocked so muscle contraction moves in a wave…collagen around them enhances force of contraction!
Muscle Anatomy:
- Myotomes interdigitate in complex ways, with some parts of an individual muscle block ____ and others ____ to form a series of ___.
- extending forward
- back
- intermeshing cones
Muscle Anatomy:
- The intermeshing cones formed from myotomes generates what?
- a body wave that propagates smoothly and sinuously along the body and with the addition of a caudal fin produces the vast majority of a sharks propulsive force.
Muscle Anatomy:
- In a cross section, shark swimming muscles form?
- bundles of concentric rings that meet at the midline of the body underneath the lateral line.
L> there is a rich network of capillaries in red …lots of oxygenated blood!
Why should you not hold a shark by the tail?
- only support for organs = collagen mesh and it can break loose very easily!
Muscle Anatomy:
- The muscle bundles that are above the lateral line are called what? Those below?
- epaxial (back)
- hypaxial (flank)
Muscle Anatomy:
- The arrangement of muscle fibbers in a shark is quite different/similar to that of a teleost.
different
Muscle Anatomy:
- Whereas in a boney fish, muscle fibers tend to loop back on themselves, in sharks the muscle fibers?
-they attach to tough longitudinal struts composed of connective tissue. These struts may act as an auxiliary muscle attachment point along the flanks compensating for shark’s lack of ribs.