Presentation on theme: "Asexual Reproduction. Asexual reproduction occurs when there is only ONE parent involved."— Presentation transcript:
Asexual reproduction occurs when there is only ONE parent involved
One parent??? Now just how can that happen???
Well, asexual reproduction can happen mainly in one of three ways: binary fission budding regeneration let's take a look at each of them...
1. Binary Fission Binary fission happens when one little cell just simply splits into two cells. Then those two cells split into four cells and then, well you get the picture...
The creatures that reproduce this way are not the glamorous ones...bacteria and protists mostly. You know what bacteria are...remember when you had that really bad sore throat? If you have ever had strep throat you have had millions of little streptococci bacteria asexually reproducing in your throat.
Here's what a diagram of strep would look like: Huh?? “step”?
But what does it REALLY look like?
Pucker Up! Dang! So nasty it made the dog puke (or maybe he's just thirsty)
O.K., here's how binary fission happens......... Pretty simple really......
Remember the protists???? Here are two types that are going through binary fission. Euglena Paramecium
Protists are just little single-celled creatures that can only be seen using the microscope. Here are the actual creatures going through binary fission. EuglenaParamecium
2. Budding The best way to describe budding is this: 1. Picture your science teacher standing in class. 2. You start to notice a bump growing out of your teacher's side. Each day it gets larger. 3. You start to see a head develop along with arms and legs while still attached. 4. You then realize that the growth starts looking EXACTLY LIKE your teacher! 5. After its grown it will pop off and live on its own. That's budding. But, there has to be a scientific definition.....so here it is: Budding - a form of asexual reproduction in which a new individual grows off of the parent organism.
Which creatures can do this??? Not a lot of organisms can go through the process of budding. Humans can't. Your dog can't. Just about the only creatures that can reproduce this way are: Yeast Sea Squirts Sponges Coral Hydra (and maybe a few more that I don't know about........but not many more.......)
Yeast Sea Squirt SpongeCoral
Let's look at the hydra more closely The name hydra comes from Greek mythology. The hydra was a many-headed nasty creature that breathed all kinds of toxic and nasty stuff. According to the legend, if you cut off one of the hydra's many heads two would grow back in it's place. Hercules had to whack the hydra as one of his 12 labors. Here's what some thought the hydra might look like.....
The hydra in biology looks like this:
How big is it? Well, that's aquarium gravel in the picture below.
Here is a diagram of the hydra budding -
Here are some actual pictures of the hydra budding -
And some more.......
This picture even show a hydra getting ready to eat...and spitting back out the “shell”of the creature it ate.
And finally, Regeneration Regeneration, simply put, is growing back a part of the body that has been cut off. Most animals have this capability but it is very limited in higher animals and humans. Most lower forms of animals can regenerate quite effectively. Here are some animals that have good powers of regeneration:
Planaria Light sensitive eyespots... not real eyes...
Starfish like eating oysters. Oyster farmers don’t like this (they are cutting into their pearl profits).
So, in the old days, divers simply cut the starfish in half thinking they killed it. What ended up happening is that they doubled their problem because the starfish regenerated. Here are some pictures of the starfish in different stages of regeneration:
Sponge farmers learned long ago that when they cut the sponge off of its base to leave a little. That little bit would grow back into a new sponge New sponge = more $$$
Despite the common myth that a worm split in two will eventually grow into two worms, they don't actually have that ability. Still, earthworms very resilient. An earthworm can survive being cut almost in half. The tail will die, but the head section will grow a new tail, thinner and sometimes a different color than the original.
Crayfish Cut off a claw and the claw will grow back. After about two molting cycles the claw will be back to its original size.
Lizards & Salamanders Lizards and salamanders can regenerate. They do this because if a snake or bird has them by the tail they can loose the tail. The bird or snake gets a snack and the lizard/salamander doesn’t die. Gecko’s commonly do this.