The Treaty of Guadalupe Hidalgo, signed February 2, 1848, ceded Texas, New Mexico, and California to the US, completing American claims to land all the way across the continent. In return, the US assumed all monetary claims of US citizens against the Mexican government and paid Mexico $15 million. The West was now officially open and secure to Americans. Despite patriotism engendered by the war, sectional conflict grew more dramatic between 1846 and 1848. Not all of this was due to expansion.
They have a shell, made mainly of calcium carbonate, which is covered by skin. The skin conatins cells to help support and maintenance the skeleton, pigment cells, cells to detect motion on the animal's surface, and sometimes gland cells which secrete sticky fluids or even toxins.
Echinoderms live exclusively in marine systems; they are widely divergent, with over 7,000 known species in the phylum. Echinoderms have pentaradial symmetry and a calcareous endoskeleton that may possess pigment cells that give them a wide range of colors, as well as cells that possess toxins.