Ireland has 375 fish species in its coastal waters and 40 freshwater species in its rivers and lakes. Most of these are pelagic. There are many aquatic mammals too, such as bottlenose dolphins, orca whales, and harbour porpoises. Sea turtles are also common off the western seaboard, and the walrus has also been found around the Irish coasts, but is very rare with only a handful of sightings. The cool, temperate waters around Ireland contain a huge variety of marine invertebrates Some of this diversity can be observed in tide pools.