DNA replication is said to be semi-conservative because of this process of replication, where the resulting double helix is composed of both an old strand and a new strand. ... Semiconservative replication would produce two copies that each contained one of the original strands and one new strand.
When echinoderms move in a manner such as walking or crawling, they pump sea water through a series of internal body canals. The water is used to inflate some of the tube feet, causing them to expand. In many species, the tube feet are equipped with suc(k)ers that grip onto the sea floor.