Reproductive System
Reproduction
Okay, so that couple above this sentence isn't a bog turtle couple, but it is how all turtles mate with one another.
First, males attract females with sounds and movements, and they are all different according to each species. For example turtles might bob their heads. Others might dance and make clucking noises. The male bog turtles bites a female bog turtle's head and tries to recognize what gender she is, since it is almost impossible to tell which is male and which is female. Once mating calls are over, the male turtle mounts the female, getting on top of her shell from behind her. This is important because this is how their tails meet. Believe it or not, the males' penises are located in the tail, and he inserts it into the female's cloaca, a small opening in her tail [1]. This can last 5-20 minutes, sometimes up to an hour. Females mate once or twice, and males can mate whenever the heck they want [2].
Oh yes, these pictures are a little bit inappropriate.
First, males attract females with sounds and movements, and they are all different according to each species. For example turtles might bob their heads. Others might dance and make clucking noises. The male bog turtles bites a female bog turtle's head and tries to recognize what gender she is, since it is almost impossible to tell which is male and which is female. Once mating calls are over, the male turtle mounts the female, getting on top of her shell from behind her. This is important because this is how their tails meet. Believe it or not, the males' penises are located in the tail, and he inserts it into the female's cloaca, a small opening in her tail [1]. This can last 5-20 minutes, sometimes up to an hour. Females mate once or twice, and males can mate whenever the heck they want [2].
Oh yes, these pictures are a little bit inappropriate.
Let me dig in a little big more about the cloaca.
According to Dictionary.com, a cloaca is defined as "the common cavity into which the intestinal, urinary, and generative canals open in birds, reptiles, amphibians, many fishes, and certin mammals."[3] In reproduction, the cloaca in females are used to 1) insert the male penis and 2) lay eggs. The gametes join in internal fertilization in bog turtles, since the male deposits sperm in the cloaca of the female.
According to Dictionary.com, a cloaca is defined as "the common cavity into which the intestinal, urinary, and generative canals open in birds, reptiles, amphibians, many fishes, and certin mammals."[3] In reproduction, the cloaca in females are used to 1) insert the male penis and 2) lay eggs. The gametes join in internal fertilization in bog turtles, since the male deposits sperm in the cloaca of the female.
Now, the gametes of the bog turtle (sperm and egg) are the same as the human gametes. It's just that the haploid number of chromosomes in a bog turtle's gamete is 25 (diploid is 50). Humans have 23 haploid chromosomes in a gamete. Other than that, they have the same structure.[2]
Bog turtles take about 5 to 8 years to reach sexual maturity [4].
Bog turtles take about 5 to 8 years to reach sexual maturity [4].
Wait, before moving onto the organs, it's important to learn what asexual and sexual reproduction is. Asexual reproduction is the reproduction of body cells. It performs a process called mitosis (it's also when your sister steps on your toe. My-toe-sis) to replicate body cells. This happens in all organisms!
Before mitosis starts, all body cells go through a phase called Interphase. A body cell spends 90% of its life in interphase, when they just do regular functions and their jobs.
When it's time to asexually reproduce, the cell goes into a phase called Prophase. During prophase, the DNA in the nucleus of the cell starts to condence and form chromosomes, so that it doubles into 100 chromosomes (remember, in turtles, the diploid number of chromosomes are 50. Now double that). The nuclear membrane starts to disappear, and the centrioles start to move towards different ends of the cell.
During Metaphase, the phase after prophase, the spindle fibers are formed in the centrioles and attaches to each centromere of the chromosomes. The chromosomes start lining up in the middle of the spindle (called the metaphase plate).
In Anaphase, the shortest phase in mitosis, the chromosomes separate at the centromere and split apart into half. The spindle fibers start shortening along the way, and pull the chromosomes to each end.
Finally, in Telophase, the chromosomes have finished moving to the different poles of the cell. A new nuclear membrane starts to form around each new complete set of chromosomes, the number of chromosomes being 50 again. The DNA then starts to uncoil again to form chromatin, one chunky mess of DNA. Since the cell did not split yet, this is where cytokinesis occurs. After the reformation of the nuclear membrane, the cytoplasm divides. This now makes 2 daughter cells that are identical to the parent, but smaller! [8]
Before mitosis starts, all body cells go through a phase called Interphase. A body cell spends 90% of its life in interphase, when they just do regular functions and their jobs.
When it's time to asexually reproduce, the cell goes into a phase called Prophase. During prophase, the DNA in the nucleus of the cell starts to condence and form chromosomes, so that it doubles into 100 chromosomes (remember, in turtles, the diploid number of chromosomes are 50. Now double that). The nuclear membrane starts to disappear, and the centrioles start to move towards different ends of the cell.
During Metaphase, the phase after prophase, the spindle fibers are formed in the centrioles and attaches to each centromere of the chromosomes. The chromosomes start lining up in the middle of the spindle (called the metaphase plate).
In Anaphase, the shortest phase in mitosis, the chromosomes separate at the centromere and split apart into half. The spindle fibers start shortening along the way, and pull the chromosomes to each end.
Finally, in Telophase, the chromosomes have finished moving to the different poles of the cell. A new nuclear membrane starts to form around each new complete set of chromosomes, the number of chromosomes being 50 again. The DNA then starts to uncoil again to form chromatin, one chunky mess of DNA. Since the cell did not split yet, this is where cytokinesis occurs. After the reformation of the nuclear membrane, the cytoplasm divides. This now makes 2 daughter cells that are identical to the parent, but smaller! [8]
Sexual reproduction is a little different. Instead of mitosis, we have meiosis.
Meiosis only involves with gametes, which are sex cells. This also occurs in all organisms. Meiosis is not that complicated, since it is only the double the amount of work of mitosis.
The first half of meiosis is called meiosis I, with the steps Prophase I, Metaphase I, Anaphase I, and Telophase I. They are the same steps as mitosis, except that this now involves with separating homologous chromosomes, not the sister chromatids. Homologous chromosomes are just two similar chromosomes, one from mom and one from dad.
There's another reason why meiosis is different from mitosis: the chromosomes in meiosis start crossing over, which is a process when the homologous chromosomes trade and mix parts of themselves with each other. This is performed in Prophase I.
After Telophase I, meiosis II begins. After the cell has split into two, each of the two daughter cells perform meiosis so that four daughter cells are made. In each of the daughter cells, the same steps happen as mitosis. The separated chromosomes split again from the centromere, nuclear membranes are formed, and cytokinesis is performed, ending with not two, but four cells. But remember, this is meiosis, not mitosis, and before any of this happened, crossing over was performed. In mitosis, the two daughter cells are exactly alike. But in meiosis, the four daughter cells are all different.
Meiosis only involves with gametes, which are sex cells. This also occurs in all organisms. Meiosis is not that complicated, since it is only the double the amount of work of mitosis.
The first half of meiosis is called meiosis I, with the steps Prophase I, Metaphase I, Anaphase I, and Telophase I. They are the same steps as mitosis, except that this now involves with separating homologous chromosomes, not the sister chromatids. Homologous chromosomes are just two similar chromosomes, one from mom and one from dad.
There's another reason why meiosis is different from mitosis: the chromosomes in meiosis start crossing over, which is a process when the homologous chromosomes trade and mix parts of themselves with each other. This is performed in Prophase I.
After Telophase I, meiosis II begins. After the cell has split into two, each of the two daughter cells perform meiosis so that four daughter cells are made. In each of the daughter cells, the same steps happen as mitosis. The separated chromosomes split again from the centromere, nuclear membranes are formed, and cytokinesis is performed, ending with not two, but four cells. But remember, this is meiosis, not mitosis, and before any of this happened, crossing over was performed. In mitosis, the two daughter cells are exactly alike. But in meiosis, the four daughter cells are all different.
Now that you know the difference in mitosis and meiosis, let's go back to talking about reproductive organs.
All reproductive systems have reproductive organs, so let's evaluate on that.
The pictures on the top are the drawings of a male (top) and female's (bottom) reproductive organs.
Both turtles have a cloaca, as I explained before. Cloaca is used for two main reasons: reproduction and excretion. The male inserts the penis into the female's cloaca to release sperm. The male has testes used for sperm production, also called spermatogenesis. Testosterone is also produced here. The male also has a penis used to eject sperm into the female's cloaca during intercourse. The female has ovaries that produce eggs, otherwise known as oogenesis. The female also has an oviduct, a tube connecting the ovaries with the cloaca. The sperm travels up the oviducts while the egg travels down the oviduct towards the cloaca. When fertilization occurs, the egg continues down into the cloaca. [5]
The pictures on the top are the drawings of a male (top) and female's (bottom) reproductive organs.
Both turtles have a cloaca, as I explained before. Cloaca is used for two main reasons: reproduction and excretion. The male inserts the penis into the female's cloaca to release sperm. The male has testes used for sperm production, also called spermatogenesis. Testosterone is also produced here. The male also has a penis used to eject sperm into the female's cloaca during intercourse. The female has ovaries that produce eggs, otherwise known as oogenesis. The female also has an oviduct, a tube connecting the ovaries with the cloaca. The sperm travels up the oviducts while the egg travels down the oviduct towards the cloaca. When fertilization occurs, the egg continues down into the cloaca. [5]
This is a video basically showing reproduction and laying eggs:
And here's what happens when a turtle never looks at a mirror:
Development
A bog turtle spends 42 to 80 days of incubation (inside an egg). When the egg hatches, the bog turtle takes about 5-8 years to full maturity. The average life expectancy is 30-40 years. The maximum is 50 years. [2]
Inside the egg, the turtle goes through regular stages like humans, from a zygote to an embryo in the first couple of stages by the rapid mitosis of cells.. Soon, the pupil is outlined and you can start seeing the shape of the limbs. The pupil is then starts to look distinct from the retina and the nasal processes start to grow. The genitals also start to grow.
Skin starts to show color thanks to the pigment cells growing. The forelimb, the hind limb, and the head starts to get into shape. The shell, also called the carapace, becomes thicker and stronger. Ribs are also visible beneath the carapace for some turtles. The eyes with eyelids are now completed and jaws start to form.
The feet start to form also. Soon, scales are present on the surfaces of the skin and the body starts to elongate. Then, before you know it, a full baby turtle is formed and is ready to hatch. [6]
Did you know that the gender of the turtle is determined by the temperature of the nest? There is a specific point of temperature at approximately 83-85 degrees Fahrenheit at which embryos in the nest start to become a mix of males and females. Higher temperatures than the specific point of temperature produces females, and the colder temperatures produce males.
After 45-70 days, the hatchlings break out of their eggs with a small temporary tooth located on their snout called a caruncle. When they break out of their eggs, they stay in the nest, absorbing energy from the yolk for a few days. [7]
After 45-70 days, the hatchlings break out of their eggs with a small temporary tooth located on their snout called a caruncle. When they break out of their eggs, they stay in the nest, absorbing energy from the yolk for a few days. [7]
A bog turtle lays an average of three eggs in one clutch. A clutch is produced and laid each year (by females, of course.) There is also no parental care, just like any other turtles. [2]
[1] http://www.ehow.com/how-does_4731092_a-turtle-reproduce.html#ixzz2Pq2elhRw
[2] https://en.wikipedia.org/wiki/Bog_turtle
[3] http://dictionary.reference.com/browse/cloaca
[4] http://srelherp.uga.edu/turtles/glymuh.htm
[5] http://quijano.net/tq/reproductive.html
[6] http://www.seaturtle.org/PDF/GreenbaumE_2002_CanJZool.pdf
[7] http://www.seeturtles.org/1403/hatchlings.html
[8] http://www.goldiesroom.org/Note%20Packets/14%20Mitosis%20and%20Asexual/00%20Mitosis--WHOLE.htm
[2] https://en.wikipedia.org/wiki/Bog_turtle
[3] http://dictionary.reference.com/browse/cloaca
[4] http://srelherp.uga.edu/turtles/glymuh.htm
[5] http://quijano.net/tq/reproductive.html
[6] http://www.seaturtle.org/PDF/GreenbaumE_2002_CanJZool.pdf
[7] http://www.seeturtles.org/1403/hatchlings.html
[8] http://www.goldiesroom.org/Note%20Packets/14%20Mitosis%20and%20Asexual/00%20Mitosis--WHOLE.htm