Answer:
Since sea urchins are picky, they are used as indicator organisms in public aquariums to determine if the system is functioning properly. This is because they are very "picky" about water quality. If the water is contaminated, the sea urchins will be the first to show signs of stress, spines laying down or falling off. Do use an aquarium filter and do clean up the day after feeding. Any metal exposed to the seawater will corrode and poison the tank. A dying sea urchin will often spawn out and rot out, causing the others in the tank to spawn and die as welll.
Explanation:
Involuntary, meaning things in the body such as your heart is all regulated to act unconsciously while also receiving directives from the brain.
After collecting specimens from many areas of the world, Darwin noted the similarities in them. He discovered that new kinds of species could gradually grow into new ones over years.
I hope this helps ;)
In adults, stem cells remain undifferentiated until they are needed to repair or replace other cells. Stem cells can produce cells that are identical to themselves.
