Lec 9 Feeding

Question 1

What are the four primary functions of the head end of the fish? (It’s divided in two major categories..)

Answer 1

1. Feeding and respiration

2. Sensory Perception and coodrination

Question 2

What did the invention of jaws lead to?

Answer 2

1. disappearance of heavy dermal armor as fishes became more mobile
2. dependency of filter feeding was lost

Question 3

Jaws and appearance of teeth led to what lifestyle?

Answer 3

Predatory life style that involved speed. Long streamlined shape was developed and evolution of paired fins to allow greater stabilization and enhanced maneuverability.

Question 4

What’s unique about the Placodermi group? What kind of bone was it?

Answer 4

Earliest kinds of jawed fishes, that are extinct. It was endochondral bone.

Question 5

Describe the endochondral bone

Answer 5

Bone that was first laid down as cartilage.

Question 6

What are the names of the lower and upper jaw of chondrichthyes?

Answer 6

Upper jaw: palatoquadrate cartilage

Lower jaw: mandibular cartilage

Question 7

What are jaws formed by?

Answer 7

Premaxilla, maxilla and dentary

Question 8

What is the suspensorium?

Answer 8

the functional unit of the cranium that supports or suspends the jaws. The palatoquadrate cartilage evolves to form elements that makes up part of this.

Question 9

What does the palatoquadrate cartilage, in primitive tetrapods, form to?

Answer 9

It forms to the palate, roof of the mouth. In mammals, it may form the in cus, one of the three bony osscils of the middle ear.

Question 10

How does the mandibular cartilage relate to the suspensorium?

Answer 10

It takes on suspensory function, in dervied fishes, it forms an element called articular that connects the quadrate bone of the suspensorium to suspend the lower jaw.

Question 11

Dentary

Answer 11

the lower jaw

Question 12

what does the upper jaw consist of?

Answer 12

Two dermal elements: premaxilla, and maxilla.

Question 13

What are jaws replaced with, after losing endochondral bones?

Answer 13

Dermal elements.

Question 14

What is a significant change in the evolution of the upper jaw?

Answer 14

The freedom of the posterior end of the maxillary bone.
In primitive actinopterygians, the maxilla was a large bone and is immobile relative to the cranium.
In derived actinopterygians, the maxilla lost attachment to the cheek and is mobile. So its able to prevent prey from escaping.

Question 15

What increases upper jaw mobility?

Answer 15

The ball and socket joint taht developed between head of maxilla and palatine bone. New highly mobile joint is thought to be a improvement over simple connective tissue hinge.

Question 16

How does the premaxilla change through evolution?

Answer 16

primitive teleost, premaxilla is small. Major tooth bearing bone is maxilla.

As teleosts evolve, the premaxilla begin to elongate and overlap the maxilla, and takes more of the tooth bearing function of the upper jaw.

Question 17

What is the ascending process?

Answer 17

Premaxilla develops into this, premaxilla extends upward and backward to overlap the snout region of the head.

Question 18

What is the ascending process function?

Answer 18

Allows jaw to be protruded away from the snout. It functions as a lever to thrust the premaxillae forward.

Question 19

What are the three distinct ways of how fishes feed? Covered in this class..

Answer 19

1. Hit and Run
2. Filter Feeding
3. Gape and suck

Question 20

Who uses the hit and run strategy?

Answer 20

Used by mostly fast swimming open water. They simply run down, engulf and swallow more slowly swimming prey, or bite off a chunk on the way.

Question 21

What are characteristics of hit and run fishes?

Answer 21

Requires firm jaw construction and large powerful muscles to get the jaws shut firmly and quickly. Upper jaw is fused to the cranium.

Question 22

What are characteristics of filter feeders?

Answer 22

Have the ability to open their mouths and to hold them open for long periods of time as they swim through the water, straining of filtering out small planktonic organisms. Very few fishes feed this way.

Question 23

Gape and suck characteristics

Answer 23

depends on ability to create sufficient negative pressure to suck individual food items from the surrounding water.

Question 24

What is more important in filter feeders/gape and suck? Strength of bite or shape and size?

Answer 24

Shape and size becomes more important.

Most fishes are gape and suck feeders too.

Question 25

In the primitive teleost. what are the structures of the maxilla and premaxilla like?

Answer 25

maxilla is toothed and forms large part of the gape of the mouth.
Premaxilla is small and only slightly mobile, no upper jaw protrusibility.

Question 26

Significance of perciformes?

Answer 26

Group of teleosts that evolved protrusible jaws.

Question 27

What are the potential of protrusible jaws?

Answer 27

P. Jaws increase overall effectiveness that helps allow increased suction pressure.

Biggest improvement is greatly increased evolutionary potential of mouth parts to evolved in dif directions.