Sea urchins are preyed about by many predators that inhabit their marine environment, but also those animals that don't. The main predators of the sea urchin are crabs, large fish, sea otters, eels, birds and humans.
Interphase is the phase during which the growth of the cells take place along with the metabolic activity but the nuclear division in the cell does not occur. The three stages included within the interphase are the G1, S and G2.
Chromatin. The nucleus contains the chromosomes of the cell. Each chromosome consists of a single molecule of DNA complexed with an equal mass of proteins. Collectively, the DNA of the nucleus with its associated proteins is called chromatin.Most of the protein consists of multiple copies of 5 kinds of histones.These are basic proteins, bristling with positively charged arginine and lysine residues.ach chromosome consists of a single molecule of DNA complexed with an equal mass of proteins. Collectively, the DNA of the nucleus with its associated proteins is called chromatin. Most of the protein consists of multiple copies of 5 kinds of histones.