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sierraschool · 2 months ago

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Soil Science 2/24

Okay, this is a class I struggle a lot with. I am taking this class instead of chemistry or physics, but I am personally not interested in the topic at all. I think my professor is very smart and my lab TA is awesome, but I cannot get into the content. Hoping this blog will save me a little bit.

Lets talk about some soil water. Since I started this blog a little late into the semester, you are going to be learning about the last segment of this chapter.

Unsaturated flow:

Flow is determined primarily by matric potential

matric potential measures how loosely the water is held (positive values means water moves easily, negative values mean water is held tightly)

its essentially the stickiness of water to soil particles

low matric potential is dry (negative numbers), high matric potential is wet (positive numbers)

Water moves from areas where it is loosely held -> areas where it is tightly held

Infiltration: process by which water enters the soil pore space and becomes soil water

Infiltration capacity: rate at which water can enter the soil

infiltration is not constant overtime

it is dependent on the soil texture and structure

quick in dry soil

slow as clays are hydrated

Percolation: movement of water downward

due to both saturated and unsaturated flow

Wetting front: where wet soil meets dry soil as water moves through a soil

due to matric potential and gravitational potential

Unsaturated flow through a profile:

From coarse to fine:

DOWNWARD: water goes through coarse, but at finer texture percolation slows and lateral (sideways) water movement increases

UPWARD: if there was enough capillary action, the fine texture would keep pulling water up through the coarse until it was saturated

(capillary action: ability of water to move upward due to attraction to itself and solid surfaces)

From fine to coarse:

DOWNWARD: water will not move into coarse until fine is full

UPWARD: water will not move into coarse until fine is full

This is all I have for today, we had barely anything left in the chapter, and honestly she moved on to the next unit even though our exam isn't until Friday and it made me mad so I just started playing HayDay on my iPad. I did know all of the answers to the quiz without having to check my notes today, so I do want to share that little accomplishment!

I want to try to post daily, so on weekends I may blog about my social life, my studying, or maybe even my job if I feel like it

xoxo <3

#soil science #soil #TAMU #learning #lecture #sierraschool

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sierraschool · 2 months ago

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Vertebrates 2/24

today in verts we talked about turtles. apparently, turtles have a lot going on that make them super freaky when it comes to their sister taxa.

Lets start with this question: What exactly ARE turtles?

Order Testundies

Sauropsida

Only 361 alive species across 14 families

Instantly recognizeable because of shell

What is so weird about them?

Turtles have anapsid skulls, and are the only amniotes (vertebrates that lay amniotic eggs) with this condition

What is an anapsid skull?

Anapsid skull is a type of Temporal Fenestration.

Temporal fenestrae are openings in the skull that are behind the eyes which allow movement of the lower jaw.

Anapsid means no fenestra, so the only opening are the orbits (eye holes) and nostrils. (turtles)

Synapsid means single fenestra, which is the lower fenestra. (this is what humans have, including mammals and mammal like reptiles)

Diapsid means two fenestrae, which are upper and lower. (lepidosaurs and archosaurs [lizards/snakes, crocodiles/dinosaurs/birds, respectively])

The big question with turtles anapsid skulls is: were they always this way, or did they lose their synapsid/diapsid condition?

The answer comes from the fossil record. In the past we can see that the synapsid condition appears in turtles once in the synapsid lineage, and the diapsid condition appears once in the sauropsid lineage. This proves that turtles evolved to have the anapsid condition in their skull, making it a secondary condition.

2. Modern turtles lack teeth

Jaws of turtles are surrounded by a hard keratinous sheath. Keratin is the same thing our fingernails are made of, but this is a much thicker and denser makeup of it. It has a very sharp beaklike shape that is good for cutting plant and animal material. This is good, because most turtles are omnivores or carnivores.

There are some turtles that are herbivores, but these are usually stenophagous (specific diet) and only eat a certain food in general.

3. Modern turtles are divided into two groups

Cryptodira

262/361 species belong here

head retracts as a vertical S-bend

known as "S-necked" turtles

found in fresh water, marine, and terrestrial

Pleurodira

99/361 species belong here

head retracts by bending horizontally into shell

known as "side-necked" turtles

All freshwater

4. Turtle Shells

Formed by 3 elements

Endoskeleton (spine, ribs, clavical)

Exoskeleton (dermis)

Epidermis (keratinous scutes)

Two halves of shell are:

carapace (top)

plastron (bottom)

The carapace is covered in scutes, which are the individual outlined shapes on top. Under the carapace is bone, dermal and endochondral. Dermal bone is the lower layer and endochondral is the upper layer.

Now lets talk about the types of shells:

Hinged shell

Hinge in the middle that allows the plastron to close the front and back opening of the shell

Double hinge on either end

Weird shells

Lack keratinous scutes and bony plates are reduced

Lack keratinous scutes and the bony plates are replaced by thousands of dermal bone

Evidence of turtles date back to the triassic period

5. How do turtles breathe?

Before getting into this, it is important to note that during development, turtles ribs fuse to their shell, which is good because it reinforces their shell, but it also changes how they breathe in comparison to other amniotes.

Amniotes use a process called costal ventilation, which is where when the lungs expand with air, the ribcage moves with it, and then when the lungs exhale, the ribcage goes back to normal. Because turtles cannot move their fused ribcage, they had to adapt a new way of breathing.

Instead of moving their lungs, turtles move their guts!

when the turtle inhales, the lungs expand. a few muscles and membranes surrounding the guts stretch and allow the lungs to push their gut downward

when the turtle exhales, the muscles and membranes push the guts back up towards the deflating lungs

This causes problems for many turtles functions.

when a turtle is fully retracted inside of its shell, it cannot breathe and must hold its breath

Sea turtles cannot breathe when they walk. they must walk, then take a break to breathe

Most turtles can breathe when they walk due to their diagonal gait. They walk with their left back foot and right front foot, and then right back foot and left front foot.

Aquatic turtles must come up for air, which makes them vulnerable to predators. Luckily, they can hold their breath for a very long time.

There is another way for turtles to breathe which is honestly pretty funny. I'm being completely serious when I tell you, some of them can breathe through their buttholes. They literally open their butthole over and over and pump water in and out and are able to diffuse oxygen from the water. This is really good for them to not have to surface, especially for turtles who get trapped under ice in colder months.

6. Turtle reproduction!

Lay on average 4-5 eggs, or even up to 100 eggs!

Almost no parental care, layed egg and then you are on your own!

Temperature dependent sex determination (TSD):

temperature determines sex of turtle. (Humans are the organism with gender, everything else is sorted by sex)

changes of even 3-4 degrees can determine sex

Lower temps mean males while higher temps mean females

Challenges of reproduction:

Few eggs and slow maturity mean turtles do not reproduce fast enough to combat endangerment

Pet trading, food collection, medicine, habitat destruction, and pollution all affect turtles

Global warming effects TSD and creates a disproportionate ratio of sexes which affects future reproduction as well

Over half of the 361 species are endangered

In conclusion, turtles are funky. We need to protect them to ensure they stay on our earth!

#turtles #turtle #science #lecture #wildlife management #TAMU #sierraschool #A&M

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sierraschool · 29 days ago

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Verts Lecture 1 Review for Test 3

Hey guys its been a while since I last posted but I am studying for my exam that is on monday so I am gonna HOPEFULLY make some posts to study

Here is the first lecture content for exam 3

Major Groups of Craniata:

Vertebrata, Gnathostomata, Osteichthyes, Sarcopterygii, Tetrapoda, Amniota, Sauropsida, Diapsida, Archosauria

Characteristics of Amniota

Amniotic Egg

Costal Ventilation of Lungs

Impermeable Skin

Temporal Fenestration

Geological Time Scale

Characteristics of Archosauria

Antorbital Fenestra

An extra fenestra hole in front of the eye

Shape of the orbit

Not a circular shape, more of a teardrop shape

Teeth

Sharp fangs

Bipedalism

Ability to walk on two legs

Fourth Trochanter

A part of the bone that sticks out on the femur for muscle attachment which allows for quicker bipedal running

Characteristics of Crocodilians

nostrils on tip of snout

allows them to breathe while mostly submerged in water for hiding and idle hunting

Secondary palate separates mouth from nasal passages

Humans also have this! it separates air from food and water and also allows them to hold prey under water while also breathing through their nostrils.

Flap of tissue at base of tongue can seal mouth and throat from water

allows them to close off their throat while they dive under water so no water is breathed into lungs. this is important for eating underwater.

depressor mandibulae

short WEAK muscle that opens the mouth. crocodiles have a powerful bite, but once that mouth is closed it is difficult for them to open it again. it is weak because the closing muscles are a lot stronger

ventricular septum in the heart

wall that separates chambers of heart. allows them to control where they send blood when it is needed more in certain places

hunt in water

ectotherms

temperature is controlled outside of body

Parental care

help young out of eggs

young stay with parents for years

Differences in heart in crocodilians

4 chambered, but one aorta from each ventricle are connected by foramen of panizza

foramen of panizza

opening that allows for mixing of oxygen rich blood and oxygen poor blood for fast oxygen use when needed

Blood flow patterns

Resting:

croc is just hanging out. oxygen rich blood comes from the lungs and is sent to the body and then sent back to lungs as oxygen poor to gain more o2. very similar to humans/mammals

Activity:

when hunting or moving a croc needs oxygen fast, so they will often mix a bit of oxygen rich blood with oxygen poor blood and send that through the body to boost them with short bursts of energy

Diving/Thermoregulation:

when they stay underwater for a long time, lungs arent bringing in any more oxygen. they use the foramen of panizza to mix together oxygen rich and oxygen poor blood and then "shunt" it through the body. they do not send any blood to the lungs since oxygen isnt coming in and they instead use that all for staying under as long as possible

Groups of Dinosaurs

Ornithischia and Saurischia

Both bipedal, legs splayed directly under body

Ornithischia

all extinct, herbivorous, diverse morphological forms, many had cheeks and horny beaks rather than teeth

a. Thyreophora - armored dinosaurs

b. Ornithopoda - duck-billed dinosaurs

c. Marginocephalia - pachycephalosaurs

Saurischia

a. Sauropodomorpha - brontosaurus

b. Theropodomorpha - trex

#sierraschool #tamu #texasa&m #texas a&m #learning #crocodilians

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