In most bilaterians, the original hole that formed from gastrulation gives rise to the gut. They are called “protostomes” (= mouth first). In a few phyla, the original hole forms the anus, and the mouth breaks through later. These are the deuterotomes (= mouth second), and they include our own phylum, Chordata, the Echinodermata (starfish, sea urchins, etc.) and a couple more obscure phyla. Some sort of gill slits in the pharynx for filter feeding in water are also a general feature of deuterostomes, although they have been secondarily lost in modern echinoderms.