There are currently 22 coral species listed as threatened and three listed as endangered. Warming temperatures, coral disease, ocean acidification, sedimentation, and fishing are all contributing factors. Baby coral in Australia's Great Barrier Reef have declined by 89% due to mass bleaching in 2016 and 2017.  

Blue Whales were abundant in the earth's oceans until the end of the 19th century at which time they became hunted almost to extinction. Blue Whales were given protection in parts of the Southern Hemisphere beginning in 1939. In 1965 they were given complete protection. Pre-whaling populations estimates were over 350,000.  today's estimates are between 8,000 and 14,000. 

Three species of Sea Turtles are either Endangered or Critically Endangered. The other three species are classified as vulnerable. See Turtles maintain the health of the ocean from maintaining productive coral reef  ecosystems to transporting nutrients from the ocean to beaches and coastal dunes.  

The Hawaiian Monk Seal  and the Mediterranean Monk Seal are the two remaining Monk Seal species left in our oceans. The Caribbean Monk Seal is now believed to be extinct.  The last sighting was in 1952 and in 2008, the species was officially declared extinct.