Search

This is a primitive kidney of a microscopic animal, Asplanchna and you are watching it produce urine! This is a bit challenging to explain I hope I do a good job, please let me know after reading.




Asplanchna is a bit larger than half a millimeter, and looks like Casper the Friendly Ghost. It's microscopic but it has many organs like guts, an ovary, a bladder and this simple kidney known as the protonephridium.

.

The four finger-like structures, each with a little wiggling flame kinda thing inside, are called the terminal organs and the wiggly structures are actually called the flame cells because of the flickering flame-like appearance.

.

In the second clip, you can see that a big portion of Casper's body looks empty, that's called the body cavity and it's not empty at all! It's filled with body fluid and Casper has to maintain the composition of the body fluid to continue its life.



So those four finger-like terminal organs are inside the body cavity and reabsorbing the body fluid for filtration. I couldn't find concrete information on what causes fluid to flow from the body cavity into the terminal organs, but a couple of sources indicate that it may be the flickering of the flame cells that causes a negative pressure and sucks the fluid in for filtration.


And each of the terminal organs connects to a hollow tube, I said the terminal organs were like the fingers and you can imagine the hollow tube as coiling in the palm of the hand. In this tube, Casper actively chooses what to reabsorb or excrete; if it's put into distilled water where there are no dissolved matter, the water flows and fills Casper's body and the kidneys react to this by increasing the excretion of water and decreasing the excretion of sodium, potassium, etc.


And this part of the active selection of what to pee and what not to pee is energy consuming so there are a lot of mitochondria, the powerhouse of the cell, around this hollow tube providing energy for the process.

.

The hollow tube connects to the bladder, and the bladder contracts when it gets full and excrete the urine out of the body through a special opening! They pee like the kids in the public pools; quite often, every minute or two!

.

Thank you for reading!

Best,

James Weiss



This is a cute water bear with a bunch of eggs and she is trying to shed her exoskeleton. Look at her eyes, they are melting my heart.

.

Water bears have this exoskeleton-like cuticle and because the bears keep getting larger in their couple of months long life, they need to shed their cuticle a couple of times.

.

Can you see the big, round structures inside the water bear? They are eggs, well, they are called oocytes but I will refer to them as immature eggs. And the sweetest thing about this species is that, when they carry these immature eggs, they half-shed their cuticle and lay the eggs into that and carry the eggs until they hatch and the babies crawl away.

.

And this mama is just scratching off the cuticle under the glass, you can see that she already freed her front legs from the small-sized cuticle. She will get rid of the rest and will lay the eggs inside and carry them around like a potato sack. This behavior of mothers carrying eggs for days is described as one of the most primitive versions of parenthood. Well, I've seen worse amongst human parents.

.

Thank you for reading,

Best,

James Weiss