BIO 461 - Exam 3 - Adaptation to Marine Environments PowerPoint Flashcards
What challenges does a species face to shift from a terrestrial to a marine environment?
- Locomotion
∙ ↓ gravity, ↑ drag
∙ Currents: clockwise in the northern hemisphere and counterclockwise in the southern hemisphere. Moving against a current takes a lot of work. - Respiration
∙ Obtainable oxygen at surface only - Temperature
∙ Water specific heat 4X that of air to heat water.
∙ Colder with increasing latitude & depth. Surface temperature at low latitudes could be 25 °C and at high latitudes could be 5 °C. They need to be able to tolerate colder depths.
∙ Currents: The difference is currents flow clockwise, so water coming along the west coast is coming from the north (high latitude environments) so it is going to be cold water. Same flow on the east side of the country, so the water is coming from the subtropic area, and bringing warm water up.
(1) What 3 challenges does a species face to shift from a terrestrial to a marine environment?
Sight
∙ Reduced light with increasing depth
∙ Different light refraction of air and water – a stick in the water bends. Your eyeball takes images from air, puts it through water (the aqueous humor in your eye is liquid), but you have a lens bends it more (light travels through air with no refraction, lights the liquid in the eye, and you bend the light) the Lense bends it more and focuses it at the back of the retina where your photoreceptors are so you can see a clear picture. In water, it comes in and there is no refraction (because it is going through water), it comes to the front of your eye (minimal diffraction) so when your Lense diffracts it, the focal point does not occur so quickly. The photoreceptors are picking up an image that is not so precise. The result is blurry vision. This is why we wear goggles (extra refraction).
(2) What 3 challenges does a species face to shift from a terrestrial to a marine environment?
Osmolality / water balance
∙ Seawater has higher osmolality than biological fluids
∙ Is osmolality going to be a big concern for most animals swimming in the ocean?
∙ Why are fish more worried about osmolality than animals returning to the ocean? The gills have a high surface area and high diffusion (ions can move freely across). As a land animal, you cannot have things moving freely across your surface, you desecrate. Osmolality and water balance is not a big of an issue. You must be able to take in ions and deal with the salt issue.
(3) What 3 challenges does a species face to shift from a terrestrial to a marine environment?
Reproduction
∙ Impacts on gametes, eggs, & young
What is thermoregulation?
What is insulation?
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different.
Limit heat exchange. Insulation limits heat transfer; it does not keep you warm or cold.
Fat vs. fur/feathers
Which is better for the ocean?
Fat makes you float, but use blubber is super dense (a lot of connectivity) that keeps them from floating as much but remain insulated and deal with the buoyancy issue. The advantage of using blubber is an energy source and reduces drag. Swimmers shave their hair and have a cap on their head to reduce resistance. Hair and feathers traps air (poor conductor and great insulator); the air is not getting changed with new air (warms up) that makes a thick barrier, even if the outer part is cold. When you are in water, that air leaves (in mammals); birds with the oil on their feathers traps the air and keeps it.
∙ Most animals that are highly adaptive for marine environments have very little fur and feathers; very short fur and feathers.
Why are Fur/feathers inferior (4 things)?
- increased resistance: you will not swim as quickly.
- increased buoyancy: you will float to the top more often.
- non-adjustable in water: when a bird or animal is cold (especially at night) they can get piloerection (goose pimples) that thickens the coat /plumage to trap air (more insulation). The hair on your head flattens while swimming (no air or thickness) and eliminate the ability to adjust it to be releasing vs maintain heat.
- not an energy reserve
If inferior in water, why do some species use fur/feathers?
They are not always in the water. They need to perform their best on land; they need to be well-insulated. Fur and feathers are lighter; you do not need to carry much weight around. Blubber needs to be dense so you do not float to the surface. When a heavy animal comes out of the water, it is very hard for them to move.
What is countercurrent heat exchange?
A countercurrent heat exchanger is an arrangement of blood vessels in which heat flows from warmer to cooler blood, usually reducing heat loss.
The arteries going into the flipper run past the veins in the flipper; heat transfers from the vein to the arteries. Fat around the flippers would decrease movement.
What is all the blubber going to do to the ability to transfer heat from to the environment to its body?
The insulatory value of fat is adjustable. They can have countercurrent heat exchange with their limbs, but they can dilate the vessels that through the blubber to get the blood on top of the fat. Now the fat is not insulating the blubber. The blood gets warm and circulates to the core. They can vasoconstrict their vessel when they return to the water and keep the blood below the blubber. It is a much easier adjustment underwater. There is not as much blubber on the flippers, and use countercurrent heat exchange. The arteries going into the flipper run past the veins in the flipper; heat transfers from the vein to the arteries. Fat around the flippers would decrease movement.
Define Thermal Inertia
Define Surface-to-volume ratio.
Thermal inertia; resistance to change in body temperature.
Surface to volume ratio; the rate at which heat leaves their body (proportion of heat) takes much longer in a big animal.
(1) What are 2 additional influences on body temperature?
- Size - increases thermal inertia; resistance to change in body temperature.
It took more heat to get you to the same temperature as a smaller animal. A bigger pot of water is going to take longer to cool down or heat up than a smaller pot of water, even set at the same temperature.
Less surface to volume ratio; the rate at which heat leaves their body (proportion of heat) takes much longer in a big animal. Lose heat at a slower rate = require more heat loss the bigger they are. Increases the amount of heat in your body = increase thermal inertia.
∙ Thermal inertia is the reservoir of heat that is needed to be accumulated or given off.
∙ Larger size (can get very large due to buoyancy)
∙ → lower surface: volume You will need to know surface; volume ratio for the final!
∙ → greater thermal inertia
∙ = slower change in body temperature
(2) What are 2 additional influences on body temperature?
- Blood flow
∙ Counter-current blood flow to extremities – anytime you have poorly insulated tissue (especially poorly insulated on the extremities where you have a lot of surface area) we will see a lot of use of countercurrent heat exchange. You do not want to send heat to a poorly insulated area – will be lost to the environment if it is cold. Warm artery coming from the core, passing next to the veins. Heat stays in the core, and the nutrients and oxygen can go to the extremity.
∙ Peripheral vasoconstriction/dilation:
Whatever environment; these topics will need to be covered for the final exam! And you will have to explain in context about whatever animal we are talking about. How does it help this organism (in the ocean or at high altitudes or desert).
- Thermal inertia
- Countercurrent heat exchange
- Vasoconstriction / Vasodilation
- Surface to volume ratio
Locomotion - buoyancy, but increased drag
What are 2 common trait adaptations?
Hydrodynamic to minimize drag and have paddles (tail, flippers, whole body) has wide and thin area to push off to propel forward. It needs to be thin so when you return the stroke, you do not want to push ourself back. They turn their fins (no drag) to continue forward.
∙ Streamlined
∙ Paddle
Sight
∙
∙ 3-D world - eyes on side of head
∙ Darkens with increasing depth
∙ Light refractivity different
Sea turtles do not have a membrane over their eyes. They use greasy (oil-rich) tears to put oil between the water and their eyeballs to avoid the refractivity. A convergent approach to avoid a problem (different solutions to get there).
Cetaceans (whales) never come out of the water, so they do not worry about seeing on land. Instead of having a Lense-shaped Lense, they have a spherical Lense (bends the light; designed to deal with water and the aqueous humor of the eye and focuses the light just fine by having a different Lense.
Penguins (best design) have a flexible Lense to distort. When on land, they can have it more Lense-shaped, and when in water, they can have it more spherical.
Given the challenges facing sight, especially at depth, some species use alternative senses; sound and sonar in toothed whales (dolphins).
Osmoregulation
∙ Increase plasma urea – frogs have very permeable skin that these ions can move across (could become osmotic). They increase their plasma urea (like sharks and rays).
Diving
What are the 3 big things that if you are an animal on land that uses your sight a lot, it will be compromised.
Light, temperature, and oxygen issues –
Whatever you use for insulation on land, it will not work as well in the water (it is extremely cold down deep).
If you want to have the longest dive possible, what do you do to increase the duration of time underwater?
Possible solutions:
1. carry more oxygen in body
2. use less oxygen during dive
3. tolerate oxygen deprivation -tolerate lactic acid and anoxia (anaerobic capacity).
Oxygen transport & storage associated with diving
Why not have greater lung capacity (take deeper breaths)?
If you take a deeper breath, you are going to float.
If they do not have great capacity, why would they have the ability to fill most of their lung at a time?
It is not about the dive; it is the recovery from the dive. The deeper breaths they can take, the quicker they can recover, the faster they can go for another dive instead of being at the surface. They do not have a large lung capacity, but they do have a large tidal volume.
What are 2 Non-buoyancy issues in animals
- Myoglobin (muscle) at any oxygen pressure bind to O2 better than hemoglobin. Myoglobin will steal O2 from hemoglobin. Myoglobin is not a buoyancy issue (not a gas).
- Spleen: filter out old RBCs and serve as a reservoir for RBCs. Deep divers (wattle seals, elephant seals) extremely high blood volume and large splenic mass. At rest, their spleen is very large and full of blood. After a few minutes of diving, they contract the spleen (squeeze it) and put the blood into circulation (more RBCs and O2 in the system).
Penguins have 29% O2 in the respiratory system. Why so high; what do penguins have that none of the other animals have?
They have air sacs (9) that they cannot completely empty. There is going to be some air inside them. The other animals, the O2 is in the blood (hemoglobin / large spleens). Dolphins have twice the amount of total blood and 3x the percent of O2 attached to myoglobin per kilogram.
Bottom line: they can carry a lot more O2 than we can, no matter where we put it, and they are not carrying it in their lungs.
What happens during the dive response?
∙ Heart rate during the dive decreases dramatically and stays low the entire dive. Once it surfaces, HR jumps back up and the heart beats more.
∙ What is the advantage of decreasing HR during a dive? If a muscle is working hard, it is consuming a lot of blood (oxygen). If you shut it down, the O2 consumption decreases.
∙ CO = SV x HR If you decrease heart rate, it is going to crash your cardiac output. What is the most important tissue that needs well-oxygenated blood all the time? The brain. When these animals dive, the change in blood flow to the brain does not change. The rest of the organs drops 90%.
∙ Aerobic respiration turns into anaerobic respiration. The problem with anaerobic respiration is two-fold: the glucose produces 2 vs 38 ATP. Once you begin to go anaerobic, you are going to produce a lot of lactic acid. In normal aerobic activity, you are getting rid of CO2 and water. Lactic acid is a toxin; and build it up fast. You are not producing a lot of energy from glucose, and producing a waste product that build rapidly and toxic.
Lactic acid needs to be converted to glucose (need O2 to convert it). It takes 6 ATP to convert. Costly to go into anaerobic.
Why does lactic acid skyrocket after they get back to the surface? There is not a lot of heart rate (flow) into the blood stream from the muscles. At the surface, the HR increases to get O2 and muscles release lactic acid in the blood to go to the liver to convert it to glucose.
Takes 60- 120 minutes to get it back to normal.
Flat line period – aerobic respiration – so they are not producing lactic acid. Less than 25-minute dives do not require much down time.
