This is the story of Mika Yukiko.

It's caretakers - Steph Spinelli and Kate Nestel.


I'm Mika Yukiko. A long time ago - well, more like a few days ago - I was born. But my story has yet to begin. In other words...

I have slight bipolar disorder.

DO YOU HAVE A PROBLEM WITH IT? No? Oh. Ok. Bye Bye until then!!!!!!



HHHHHHHHHHHHHHHHHHHelp i need outta this truck before i go KKKKrazzzzzzzy!!!!!

EEk! i feel out of the truck!!! OH NO!!
I'm living on the streets!

but my new street name is j'mika. hahaha.

Mika Medaka 's structure vocab in ABC order

Chorion-membrane protecting Mika (medaka)
Cardinal Vein- veins running aside the vertabral column
Embryonic Shield/Disk- mass of cells in the blatocyst from which embryos develop
Extraembryonic Epithelia- a structure that progressively begins to cover the yolk within the embryo
Otocysts- a fluid containing organ inside of animals without backbone (invertebrates)
Otoliths- a sensory organ that is used for balance and hearing in fish
Projecting filaments-entangle adjacent eggs into a cluster and attach the cluster to the female's vent.
Somite- A division in an animal's body
Vitelline Membrane- the outer surface of the plasma membrane of an ovum
Vitelline Veins- little hair-like projections off the vitelline membrane.
Vertabral column- also known as the backbone or spine
Yolk-is a yellowish or almost colorless fluid containing small oil droplets near its surface. Also it is the first site of blood formation and food source.

Day 1
[[image:mika_5:20:08_sjskmnrollrooll1.jpg width="461" height="349"]]
I'm finally off the truck! And look at me - I think I'm at stage 11.. but I'm not so sure. We'll just have to wait and see...
Kate and steph took my measurement today....eeekk i am tiny!!!! As you can see from the picture, I have a optic lens, oil drop, and a yolk..........and don't forget the somites.

Day 2

Um... am I just not growing? I still think I'm on stage 11.
In stage 11 I undergo a process called Late High Blastula. I am 9 hours old at this stage. During this stage my blastoderm is circular and 0.6mm in diameter. In the middle of the blastoderm there is about 12 layers. Peripheral cells start to lose their intercellular boundaries and large nuclei appear, beginning the formation of the syncytial periblast.

Day 3

Well turns out I was growing.. Yesterday I was at stage 13. Today I'm at 14. Steph and Kate think I'll hatch on June 1st, or in about 10 days. I'm at Stage 14 because my nucleus is moving towards the edge of the membrane. In stage 14 I am 15 hours old. My gastrula.......which kate and steph didn't label.....has expanded to cover 3/8 of my yolk sphere. A broad shield has built up at the dorsal lip. If you look closely you should be able to see a narrow germ ring that extends laterally from each side of the shield to halfway around the blastroderm..........well you might not see it on this picture but its there.....
In stage 13, which was what i was at yesterday, I'm about 13 hours old. You can see the clear crease along the membrane, which will then become the fish. My blastoderm diameter should be about .9mm.

Day 4
Wow... my stage prediction was WAY wrong. Turns out I'm at 23.. in other words, I HAVE A HEARTBEAT! YAY! My heart beats 60 beats per minute. I am about 46 hours old at this point!!!
My oil drop is positioned at the bottom end of the egg and sorta bulges the right ......see it???? kate and steph again forgot to label something..tsk tsk...o well they try their best to get the main should be able to tell what i am talking about anyways. Right above the oil drop is my tail. My tail is ever so slightly bent in this stage. As you can see steph and kate measured how big im getting!!!! They say they I grow too fast haha. I have about 15 somites at this stage.

Day 5
My heartbeat was 110 beats per minute. This is a healthy heartbeat because the number of cardiac contractions should be between 100-120 beats a minute. Im now on stage 26. I am a grand total of 56 hours old during this stage. Also in this stage i have eyes and a curved tail. In my eyes the retina begins to darken.

Today's stage was 27. I am 62 hours old. My heartbeat was 125 beats per minute. My pectoral fin bud enlarged into a rounded protuberance today. The embryo moves a little more. Also blood circulation has you can tell by my increase heartbeat rate.

Day 7
I am believed to be in the late stage of 27. My heat beat was 130. Kate and Steph observed increased in frequency in body movements and blood circulation. The blood circulation is now strong. Also they observed a bent lateral tail. I now have 26 somites.

We are a couple stages off in our predicting...........her heartbeats show that Mika is more developed then we thought ..........we just .....(sniffle sniffle) are going to miss her! We are still going with our June first prediction.
My heartrate today was 140 beats per minute. This was a huge jump!!!
Kate and steph predict that i will hatch June 1st. I believe that i am on stage 29 or 30.
Color wise, I have gotten more of a gold/yellow tint since day one. On the bottom my membrane ismore of a clear/whiteish color. My brain is more developed and takes up more space. The optic lens has formed over my eyes now. Don't worry thats a good thing....hehe I am still able to see. My optic cups have gotten larger. I also have blood that is a light pink color being pumped now through my veins and arteries instead of the colorless blood I used to have. mmmhhhh I love pink!!!!!!! Sorry im am a little ADD..hehe What else ..... well my tail is longer....I have more somites .....about 30 right now......and one last thing .....oops hmm I forgot .....what was I going to ooo ooo I know. My heart has changed it's position. It is now in a bent position so that the ventricle is now to the right and the posterior is at the atrial end.

Day 9

I am now a full grown Medaka and ready to go out in the world leaving kate and steph behind. They did a good job of taking care of me, and i will miss them. I am now at the last stage (36) which is the hatching stage. In these pictures i am around 264 hours old. I am around 3.5 cm long. My heartrate was impossible to get since i just can't keep still for more than a second. It should be around 200 -210 beats per minute. We aren't sure if our prediction was right, but we do know that it did hatch sometime over the weekend! Mika forgot what day exactly what day she was born on.....she says she has the memory of a goldfish.......three seconds. Mika: sorry girls!!!! US(steph and kate): its ok haha we forgive you. What ever day it was we were really close are first prediction was June 1st and thats today we were only a day or two off.

Mika's description:
Mika says she's so glad to be outta of that egg!!!!!!!!!!
Mika has a thin tail, large eyes and a bulky body. Mika's tail is constantly in motion. You have to look closely to see these movement. Mika was a little camera shy........she kept swimming away when we went to take the picture.......sorry we could only get head shots and tail shots......... It was soooo much easier when she was an egg haha Mika seems to have gotten darker spots compared to when she was an egg. Also she is no longer round shaped.....she is stretched out more.....more like a line shape. Also being a girl, Mika loves to talk .....her mouth is constantly moving and flapping up and down haha

Random facts about Medaka's

  • Medaka's are amphidromous meaning they move between salt and freshwater at some point in their life.
  • They are also called Japanese killifish.
  • Oryzias latipes is their scientific name.
  • It is a small ricefish about 4cm long.
  • coloration varies, from brown or yellow-gold in the wild to white, creamy yellow, or orange in aquarium-bred individuals
  • The medaka has been a popular pet since the 17th century in Japan.
  • Medaka's can live to be five years old.
  • The Medaka usually cost anywhere from .80¢ to $ 2.00.
  • Male Medakas are more slender with larger dorsal and anal fins then females.
  • They can be genetically enhanced to glow under a black light........however these types are not legal in the U.S.
  • The most well know type of Medaka is the Golden.


Stages of Medaka Development:

* the pink stages are the stages we got pictures of *

stage 1 The Medaka starts out as an unfertilized egg that appears to be very opague. The sphere where the yolk is surrounded has a thin layer of active cytoplasm. There are many small oil drops that are randomly distributed beneath the cytoplasm. At this time the egg is 0 hours old.
Next at stage 2 the Medaka is fertilized and is about .2 hours old. The yolk has turned a yellowish color and is clear. The oil drops have not changed.
Next at stage 3 the Medaka is about .8 hours old. The active cytoplasm comes around the zygote nucleus, which makes a cap at the animal pole. The oil droplets have began to move to the ventral hemisphere and begin to fuse.
Then at stage 4 there are fewer oil droplets and the medaka is 1.5 hours old. The remaining oil droplets have enlarged, and the fusing of the droplets continue throughout the early development of the medaka.
In stage 5 it is 2 hours old, and the second cleavage plane is at right angles to the first.
At stage 6, 2.5 hours old, the third cleavage plane is at a right angle to the first.
At stage 7, 3 hours old, the fourth cleavage plane is parallel to the second, resulting in a single layer of cells. The cells are arranged in two rows of four cells.

Stage 8, 3.5 hours has the number of cells being 32, for the four central cells of the sixteen-cell embryo have divided tangentially.
At stage 9, 4 hours there are 64 cells and two layers of blastomeres, surrounded by sixteen outer cells.
At stage 10, 6 hours, the blastoderm has five layers. There are about thirty outer cells are continuous with the yolk cytoplasmic layer. The ventral surface of the blasutla is flat.
At stage 11, 9 hours the blastoderm is circular in structure and comprised of 12 layers so it is about 0.6 mm in diameter.
Stage 12, 12 hours has the blastoderm flattened and expanded.
At stage 13, 13 hours, a thing crease clearly marks the dorsal lip where the involution begins. And the blastoderm diameter is about 0.9 mm.
Next during stage 14, 15 hours old, the gastrula has expanded to cover 3/8 of the yolk sphere, and a broad shield has built up at the dorsal lip. Also, a narrow germ ring is extending laterally from each side of the shield to halfway around the blastroderm.
At stage 15, 17 hours, the blastoderm has expanded to the equator of the yolk sphere. The shield length narrows, and the germ ring is no longer visible.
At stage 16, 20 hours, ¾ of the yolk sphere is covered by the blastoderm. The center of the shield is more dense, because that is where the embryo is developing. There are only a few oil drops now that are located near the vegetal pole.
Then at stage 17, 23 hours the central nervous system is the streak os cells in the middle of the shield. The yolk is very large and protrudes from the blastopore.
Next at stage 18, 26 hours old, the anterior end of the keel has broadened into two divisions of the brain, and the embryo is about 1 mm in length. The blastopore is smaller and is beginning to form a small opening.
Then at stage 19, 29 hours, the closure of the blastopore is complete and gastrulation ends. The tail is also beginning to form.
At stage 20, 33 hours, the two or four pairs of somites appear. The optocoele develops within the optic vessel, which is still attached to the forebrain. There isn’t any pigment in the yolk or the embryo. The embryo has also gotten bigger.
Next at stage 21, the pericardial cavity is defined ventral and bilateral to the midbrain and the hindbrain. The early optic cups are formed, but they are missing lens. Three brain divisions are distinquisable. There are six to eight somites. The embryo has grown to about 1.3 mm.
Next at stage 22, about 40 hours old the optic lens are small round lens, not filling the entire cup. The optic lobes are larger and the brain ventricles are forming. A new large cavigty appears on the yolk just anterior to the head. It will then move forward and fuse to the pericardial cavity.
Continuing on is stage 23, where it is 46 hours old. An early heart, and a narrow tube ventral to the head, makes the heart beat 40-60 times a minute. There are islands of blood on the yolk, but no circulation. The head and tail have raised slightly off the yolk sac.
At stage 24, the colorless blood has only a couple of cells, and it moves slowly through the aortae and vitelline vessels. The beat of the heart is strong, and is beating about 60 beats a minute. There are also redish-brown chromatophores in the floor of the brain. The embryo is about 1,5 mm long, and there are 15-20 somites.
Next is stage 25, where the embryo is 54 hours old. The anterior somited are beginning to twitch infrequently and may bend the body axis slightly, and there are now about 22 somites. The otoliths are barely perceptible lying against the inner surface of the otocyst. The tail tip is completely off the yolk sac.
Stage 26, 56 hours old, the black granules are speckled over the optic cup, and the retina begins to darken gradually. The number of cardiac contractions have increased to beating 100-120 beats a minute.
Next and stage 27, 62 hours old the pectoral fin bud has a broad swelling posterior to the emergin anterior vitelline artery. The embryo has begin to move more often and blood circulation is strong and increased. There are now 26 somites.
At stage 28, 74 hours old there is pink blood, and the heart is bent so the ventricle lies posterior and right to the artial end. The tail has gotten longer so it is 1.7 mm long. There are also now 30 somites.
Next is stage 29, 84 hours old, the cardinal and vitelline veins are in the path in lieu branching. The retina has pigment and can be seen. The pectoral fin is now thick and bluntly pointed. The tail moves and makes the whole animal move.
Next is stage 30, 102 hours old. The bladder is at the left of the pectoral fin. The heart beats 140 beats a minute. The blood is now dark pink, and the tip of the tail reaches the eye, and a chamber forms in the heart ventricle.
Then at stage 31, 121 hours the pectoral fin has weak twitches, and the caudal fin is developing. The urinary bladder also has a greenish tint. The cornea of the eye is visible, but still touches the lens. The chambers of the heart are differentiated and the blood is reddish in color.
Then at stage 32, 128 the liver is colorless and is at the edge of the urinary bladder. The cornea of the eye is raised off of the lens.
Next at stage 33, 144 hours old, the liver is now made up of colorless globules and covers the urinary bladder on the lft side of the animal. Most of the other organs, such as intestines are transparent. The swim bladder now appears clear and next to the urinary bladder. The lower jaw has formed and the heartbeat is 170 beats a minute.
After that in stage 34, 168 hours old, the lower jaw is beginning to move periodically. The dorsal, head, and trunk have a yellowish shadow, and the eye is able to move slightly. The cornea is well lifted off the lens. The dorsal fin is also very distinguished from the rest of the embryo.
At stage 35, the embryo is 200 hours old. The spleen is now present/visible and is the red structure between the urinary and swim bladders. The liver is also conspicuous, and the head has began to straighten out. The mouth has moved to a more upward and out position and actively moves. The yolk sac is smaller in size then before and does not have pigment. The embryo also moves more often and thrashes about.
Last is hatching, stage 36 (in some cases stage 39) depending on the source information. The eggs that hatch on day 11 usually have more yolk. There are usually about 30 somites total, and the mouth usually opens shortly after hatching, and is able to coordinate swimming and breathing. The swim bladder is the size of the oil globule, and the urinary bladder and spleen are brightly colored, and located on the left side with the liver. The ventral fin is long and wide and cut by an anal opening. The other fin, the abdominal fin, is flattened as the bladder absorbs the yolk.