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 are usually found in the shallow water near the shore. They spend much of the time resting in the sand or on rocks. Starfish can move using specialized structures called tube feet. Each arm of the starfish has hundreds of tubes with suckers on them to help them navigate over rocks and sand.chinoderms do not have a highly developed nervous system, but they do have a nerve ring that surrounds the mouth and helps to coordinate their movements and responses. Sensory cells on their arms gather information about their surroundings, such as light and temperature to help the organism respond to its environment.