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.
Answer Wiki. Chemical analysis of isolated chromosomes shows that it consists primarily of DNA and proteins with lesser amounts of RNA.The proteins are of two major classes : 1.basic proteins(positively charged at neutral pH) called histones and 2.non-histone chromosomal proteins.