Life in the Extreme Test 2
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What should be known about the microclimates of the desert?
- The grain size of the sediment becomes very hot when it is really fine.
- Vegetation in the microclimates provides shading and increases the humidity of the ambient air due to the evaporation occurring on the plant surface. Also, the soil temperature is lowered due to the water absorption by the plant roots.
- Vegetation also provides a short break from the very harsh winds.
What are the advantages and disadvantages of living in a burrow in the desert?
- Temperature varies little below 10 cm from the surface.
- High humidity
- Can be used to dump heat
- Low PO2
- Waste buildup
Describe desert ant & termite nests
The managed microclimates that are desert ant & termite nests are oriented to control temperature. The nest are flat, thin, orientated to absorb heat in the morning, and orientated to minimized heat gain during midday. Due to the design, an unofficial ventalation system keeps the nest cooler than the ambient air.
What are some adaptations naked mole rats (Heterocephalus glaber) has adapted for the desert?
- They burrow in hard soil with incisors located outside the mouth.
- They don't drink water.
- They are "ectothermic" mammals with little hair or insulating fat. They also have lowered metabolic rate due to the low oxygen content in the burrows and to prevent overheating.
Describe the behavior of the naked mole rats (Heterocephalus glaber).
- They are eusocial mammals. They live in hives with a queen, 1-3 copulatory males, and nonreproductives. The nonreproductives have a caste system. The group size can range from 20-300 individuals with the average being 60.
- They rely on the burrow temperature for heat and huddle while they sleep.
Describe the behavior and some of the adaptations of the desert ant (Ocymyrmex barbiger).
These desert ants can briefly survive surface temperature of 67°C. Their body temperatures can raise to 52°C. They exhibit stilting to minimize contact/surface area. They do seek shade when it's out. Many do die in heat stress. But, the beneifts of surviving surface temperatures are that they are the first scavenger at a carcass and that they are able to avoid predators.
What is torpor?
- Torpor is a period of reduced metabolic activity. IT IS DIFFERENT FROM HIBERNATION!
- It is used to avoid stressful conditions. (PRIME EXAMPLE OF AVOIDANCE)
- It is seen in small animals and many invertebrates.
- The normal period of torpor is 9-10 months, and the record is 2 years.
What are some different types of torpor?
- Estivation - a form of torpor induced by heat
- Diapause -a nonfeeding state where an animal shuts down
- Arrested Development - an organism will get to certain state, shut down, and wait for conditions to get better.
What are some adaptations evolved to help the desert snail Sphincterochila boisseri?
- The Sphincterochila boisseri can survive temperatures up to 65°C. It survives these high temperatures by retreating into the upper whorls of its shell, which is highly reflective to solar radiation.
- This desert snail becomes dormant for 98% of its lifespan.
What are some adaptations evolved to help the desert snail Otala lactea?
- The Otala lactea increases the production of kinases, which will phosphorylate other enzymes in order to reduce enzyme activity.
- This desert snail also exhibits estivation and utilizes carbohydrates for energy. It secretes a mucus epiphragm over the aperture (?). During its estivation, it also exhibits apnoic breathing where it only breathes 2 to 3 times per hour, and it's metabolic rate drops 10-30% from normal.
What adaptation has the Spadefoot toad evolved in order to survive in the desert?
- The Spadefoot toad has evolved a horny thing on its hind legs that allow the animal to dig. It may spend 8-10 months of the year buried, and it's metabolism willl drop 50-60% below normal. Its enzyme activity will drop due to enzyme phosphorylation.
- The toad is able to get water by absorbing it osmotically.
- Urea will accumulate in its tissues, but these can still function since the enzyme that are still active are insensitive to urea.
- This toad is able to lose 60% of its body water, which accounts for 50% of its body mass.
- This toad utilizes fatty acids for energy during its estivation.
- It will emerge and mate during the rainy season in ephemeral pools.
- The eggs hatch very quickly, less than 1 day.
- Metamorphosis occurs in this species of toad in 8-10 days.
- It produces two types of tadpoles: herbivorous and carnivorous
Describe the characteristics of the Kangaroo Rats.
- Very docile creatures
- Nocturnal - They live in a burrow where the temp is relatively constant and has a high humidity (<35°C).
- This animal can survive water. These animals have extraordinarily long noses. These noses have convoluted turbinates for heat exchange and humidity control. This mechanism only works if the air temperature of lower than the animal's body termperature. They also have external food pouches. They can survive on their metabolic water.
Describe kidney function.
- Function: filtration, reabsorption, and secretion
- Collecting tubule called the collecting duct.
- Two types of nephrons: Cortical & Juxtamedullary.
- The steeper the Loop of Henle, the more concentrated the urine.
What are some of the adaptations that the tenebrionid beetle has for surviving the desert?
- These beetles are dehydration tolerant by maintaining hemolyph osmolarity, which they can control by changing the volume.
- They have a waxy cuticle, which helps with water retention and reflection.
- Its elytra, or harden, outer wings, are fused.
- It exhibits discontinuous respiration.
- Some species can catch the morning fog and drink it.
What adaptations does the desert lizards called the Thorny Devils?
The Thorny Devils have microchannels that lead condensed water to its head for drink.
What are some characteristics of desert plants?
- Many are ephemeral.
- The seeds lie dormant until is rains. The rain washes away inhibitory enzymes to induce germination.
- Short life cycles. They only live a few weeks.
- Very long roots.
- Water storage
- Reduction of leaves to minimize surface area
What's the coldest place on Earth?
What's the coldest continuous place on Earth?
Vostock, Antarctica -89°C
Oymyakon, Siberia -71°C
What are some characteristics of penguins?
- They nest on the pack ice.
- They can go 115 days without food.
- They posses a large size, which is important in minimizing heat loss by lessening surface area.
- They have a thick insulative layers of feathers that trap air to keep them warm and of fat.
- Dark color to reflect solar radiation
- Reclaim 80% of heat in breath with its small beak.
What are tardigrades?
- Tardigrades are very small organisms (almost microscopic I think), which can survive any extreme environment on Earth.
- They're common name is "water bears."
- Can survive 3040 days in its desiccated state.
- Can survive for 600 days at -22°C
- Can survive for 150 days at -80°C
- Can survive for 14 days at -180°C
- *Can survive for a few minutes at 1 degrees above absolute zero.
What is supercooling?
Supercooling is a survival strategy where an organism can allow themselves to lower their body temperature below freezing without freezing.
Ice crystal formation is dependent on what?
- Volume of water
- Time at temperature
What are the ice-nucleating particles that must be expelled in order to supercool?
- Must have empty gut
The body fluids of ice fishes are isotonic, hypotonic, or hypertonic?
Who do ice fish avoid freezing?
They live at a deep depth where no ice forms.
What is an unique adaptation of the Champsocephalus gunnari species of ice fishes?
The only vertebrates that lack hemoglobin. Their blood only carries 10% oxygen, but they also have larger hearts, which pump blood faster, and contain more blood vessels in the gills and skin.
Describe some characteristics of polar bears
- Semi aquatic
- Live on pack ice
- Very well insulated with 2 layers of hollow hair that traps air and a thick layer of fat
- Short ears and tails to reduce heat loss
- Eat mostly blubber because has more energy and causes less urea production
- Females have delayed implantation
- 33% milkfat
Describe the characteristics of animals such as seals, sea lions, and walruses.
- Found in colder water because they are so well insulated that they'd overheat in warmer waters
- Reduced hair
- Several inches of blubber
- Flippers and tails are heat exchangers with a counter current circulation
Describe the characteristics of Caribous (Reindeer)
- Migrate great distance 3000 miles
- Have been domesticated
- Very broad feet that act as snow shoes
- Pelage - Dense undercoat with longer, hollow guard hairs. All body surfaces have hair.
- Regional heterothermy
- Eats vegetative material
Describe caribou calves
- Must thermoregulate immediately
- Very precocial
- Metabolic cost to stay warm are greatly reduced 2 weeks after birth
- Small mammals
- Active all winter
- Live in burrows
- Store food
- Build "runaways" under the snow
- Suicide myth FALSE
- Move at night when resources are low
- Can swim across water
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