The federal government is protecting 20 types of colorful coral by putting them on the list of threatened species, partly because of climate change. Five of the species are found off the Atlantic and Gulf of Mexico coasts of Florida, Puerto Rico and the Virgin Islands. The others are in the Pacific Ocean near Guam and American Samoa. The National Oceanic and Atmospheric Administration considered 66 species, but on Wednesday it listed only 20 for various reasons. Coral reefs, which are in trouble worldwide, are important fish habitats. The agency cited threats to coral from fishing practices and from global warming. Two species were already listed.