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Learning Check-List
Snapper Ecological Niche
Discuss the ecological niche of snapper
Explain the ventilation and gas exchange in the snapper gill system
Compare & contrast the advantages and limitations of this system
Tasks - Milestone #3
Engage with the videos and notes below. In your portfolio of learning complete the following tasks. It is important to paraphrase in your own words, and include the URL's and any other resources you used in your reference list. So that they are there ready for your final assessment.
1.Complete sciPAD pgs: 50-51
2.Summarise the ecological niche of snapper
3.List the ventilation structures in fish and describe how they work
4.List the gas exchange structures in fish and describe how they work. Pay special attention to the counter-current exchange system
5. Summarise the key advantages and limitations of this system
Taxonomy is the scientific study of naming, defining and classifying groups of biological organisms based on shared characteristics. Fish are an example of a taxonomic group, and snapper belong to this group.
Thinking back to your ecology learning, you will remember that an ecological niche is the functional position of a species in an ecosystem. You need to write about the ecological niche of snapper in your report and relate this back to the adaptations of the gas exchange system in snapper.
Check out the NIWA website for more information about the ecological niche of snapper.
Watch this initial video, created by a teacher in Auckland. It gives a fantastic overview of the snapper gill system, and the video below is a animated walk through of th esystem.
The diagram above shows all of the key ventilation and gas exchange structures. Pay attention to the highlighted key, indicating the key function of each structure.
FISH Ventilation
FISH Ventilation
Water flows through the mouth, past the buccal cavity. From the buccal cavity, water splits in two directions - some water flows over the gills on the left side of the head, and some water flows over the gills on the right side of the head.
Gas exchange occurs as the water is flowing over the gills, the water that is then low in oxygen but now high in carbon dioxide then exits the fish’s head through the operculum cavities.
This is type of ventilation is unidirectional, because water is pumped in one direction: from the mouth, through the buccal cavity, over the gills, through the operculum cavity, and out through the operculum.
Mechanically muscles in the floor of the buccal cavity work together to change the pressure inside the buccal cavity and open and close the operculum. If the operculum is closed, it raises the pressure, anf if it is open, it decreases the pressure inside the operculum cavity.
FISH GAS EXCHANGE - OVERVIEW
Gill rakers are bony structures projecting out from the from the gill arches, they protect the gill filaments from any debris in water that could damage the gill filaments.
Gill filaments are the site of gas exchange. They are the delicate, bright red, long thin filaments projecting out of the gill arches. They kind of look like feathers. They are bright red because they contain a large amount of blood-carrying blood vessels. Each gill filament is highly folded into many lamellae, this increases the surface area of the gas exchange surface.
Lamellae are very thin and contain these tiny blood vessels called capillaries. Lamellae are very important because they are the specialised respiratory surface of the gill system.
The counter-Current System
The counter-Current System
The key adaptation of the fish gas exchange system is that it is counter current. Meaning that the water flows over the gills in the opposite direction of the way the blood is flowing. This ensures there is always a concentration gradient to maximise the amount of oxygen extracted from the water into the gills.
In the first image on the right, below you can see that with counter-current exchange, the oxygen levels are always higher in the water when compared to the blood, this creates a high to low concentration gradient - resulting in the constant diffusion of oxygen into the blood stream. In the picture below without counter current the oxygen levels are only higher in the water for half the length of the lamella, which minimses the amount of gas exchange occuring.
The counter-current system is especially crucial as water contains far less oxygen than air does, so to meet the metabolic demands, fish need to ensure they are extracting as much of the dissolved oxygen as possible. Quite different to animals on land, where oxygen is abundant, e.g.: humans only actually use around 20% of the oxygen ventilated into the lungs, the rest is exhaled with the carbon dioxide. In contrast fish will extract around 95% of the oxygen ventilated over the gills.
Specific Adaptations of FISH
Specific Adaptations of FISH
Watch this video to summarise the key adaptations of this system in snapper. You need to write lots of detail about at least two specific adaptations in the snapper gas exchange system. These adaptations should focus around how they maximise efficiency of gas exchange.
Remember the key things that make a GE system efficient are: the GE surface being moist (for gases to be dissolved), have a high surface area to volume ratio (to ensure lots of locations for diffusion), the surface must be thin (a single cell layer thick, to minimise the diffusion distance), GE surfaces need have a rich blood supply - be highly vascularised (to transport the gases to and from the body cells), and finally gas exchange surfaces need to maintain a high concentration gradient (to ensure constant diffusion of gases across the GE surface).
ADVANTAGES & LIMITATIONS
Thes two videos are great and cover the adaptations and limitations of gills, including a good description of why the countercurrent exchange system is advantageous, and why fish need to stay in water.
Significance of being cold or warm-blooded
Significance of being cold or warm-blooded
The two key limitations of this system are:
The two key limitations of this system are:
Being incompatable with air, what happens to gills when they are out of water? and how does this effect the gas exchange surface specifically?
Being cold-blooded, how does this impact how the snapper gains and retains warmth from the environment? and why are most animals that ventilate water cold-blooded, what does the amount of oxygen available have to do with the differences in energy demands of cold-blooded versus warm-blooded animals?
limitations of being cold-blooded. The advantage that the Opah has - a rare example of a warm-blooded fish.
For lots more information visit this link..
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