Echinoderms do not spend time caring for their young ones.
They reproduce by sexual means, that is the combination of genetic materials from two separate individuals (male and female). The males provide the sperm and the females provide the eggs for reproduction. The sperms and eggs are propagated into water column, and fertilization takes place in the open water. Echinoderms commonly, leave their eggs and provide no parental care to the eggs. They don't take care of their young ones at all, however, some sea urchins incubates their eggs in special little pouches.
If the Na+ voltage-gated channels in a muscle cell open, the Na (sodium) ions rush inside the muscle cell and makes the cell more positive as Na ions carry positive charge on it. Due to the entry of positively charged ions inside the cell, the cell becomes less negative and more positive. This is called depolarization of cell.
A restraint that provides protection without having to be handled by the occupant is called ~{passive restraint.}~
