Lecture Four: Major Changes, Water, Regulation Flashcards
February 4
What is the first vertebrate we identify for this course?
Lamprey.
Still have vertebrae in extant form (hagfish do not).
What are the first jawed organisms?
Placoderms.
What relationship do lamprey have with their food?
They are parasitic. Liquid diet (blood).
Describe the diadromous capabilities of lamprey.
They live largely in salt water, but lay eggs in fresh water. Larval stage lives in fresh water, burying itself into the ground and feeds until it can change into the adult body plan.
Do lamprey adults and larvae have the same body plan?
No. Larval lamprey go through metamorphosis to become adults.
What did jaws arise from?
First and second gill arches.
Describe the positioning of the skeletal elements that support the gills in jawless fish.
External to gill filaments.
Describe the positioning of the skeletal elements that support the gills in jawed fish.
Sit internal to the gill filaments.
What body plan complications comes along with jaws? What does this combination of things help an organism do better?
- Paired appendages with pronounced presence of fins. Form fins, then limbs.
- Horizontal septum: separates back and stomach muscles. Increases mobility. Will be where the lateral line sits.
All contribute to a more active predatory capability.`
If the complication of muscle increases, what also must increase?
Number of nerves to innervate the increases muscles.
What are the major changes that occurred from jawless and jawed fish
- Jaws
- Gills structure
- True teeth come with jaws
- Circulatory changes
- Increased osmoregulatory complications
- More muscles -> increased movement
- One nostril to two.
What is a benefit to being in a marine environment?
It supports the skeleton. Less energy expenditure.
What change has to happen to the skeleton to transition from water to land. Why?
It must thicken to better support the organism since the air does not support as much as water does.
Is there gravity in water?
YES, but density (buoyancy) of water offsets gravity.
What is important to note about the overall environment on water? How do organisms impact this?
The environment is CONSTANTLY moving and the water has enough density to move large organisms.
Organismal movement in water contributes to the constant change and movement of the environment.
An organism moving forward in water may push prey away from itself due to the density of water. Jaws allow what other ability help to counteract this?
Suction.
What increased complication is associated with having two nostrils instead of one?
Anatomical complication of the head.
There is a theory that two nostrils must have preceded jaws.
Which fins help control rolling?
Dorsal and tail fin.
Minorly pectoral and anal fins.
Fins stabilize fish in which three dimensions?
Roll: Rolling
Yaw: side/side movement
Pitch: up/down movement
What plays an important roll in stabilizing fish?
Semicircular canals.
How many semicircular canals does a hagfish have?
1 pair (2).
How many semicircular canals does a lamprey have?
2 pairs (4).
How many semicircular canals do fish after the lamprey have?
3 pairs (6). (Roll, yaw, pitch).
The average depth of the ocean is 4,000m. What is the temperature of the water at that depth? How is this possible?
3.8* C.
Water is densest at around 4* C. With so much weight on top of it, the water at that depth is the densest it can be. Additionally, water has an incredible ability to thermoregulate.
