Hippos are being endangered mainly because the poachers hunt them for their meat and their ivory teeth
Two species of sea urchins live practically side-by-side in sandy bottoms. The two species appear to have the same diet: drift seaweeds and other bits of organic matter. They can live in the same environment without competing.
As it compels them to live in the same environmental surroundings so the characteristics of living nature also get developed as their current following situation that's helping them to get the same food & habitat.
D) each parent passes only one factor for each trait to its offspring
Circulatory system.....circulates blood (a vital delivery system of oxygen) throughout the whole body when tissues need it the most and with a constant supply.
