All marine mammals go through live birth. In other words, they don't lay eggs like fish. Cetaceans (whales, dolphins and porpoises) give birth to live young in the water, so the calf emerges from it's mother underwater and has to swim to the surface to take its first breath. But seals and sea lions are able to haul their bodies out onto rocks or the beach so they can give birth to live young on land.

Scotland's seas hold a great variety of marine mammals. Whales, porpoises, dolphins and seals can all be seen throughout the year. Even sea otters can be spotted along certain parts of the coastline.

The most commonly seen whales in Scottish waters include fin whales and minke whales but there are many other species which are occasional visitors to our seas. Porpoises are smaller than whales, the most common of these near Scotland is the harbour porpoise. Amongst the dolphins, common dolphins, bottlenose dolphins, white-sided dolphins and white-beaked dolphins are the most common. There are two species of seal which are found all year round along Scotland's coast - the grey seal and the harbour seal.

These species can generally be seen at any time during the year. There are many other species of marine mammal which occasionally wander into Scottish waters.

Research on whale sharks is still being carried out as we continue to learn about the world's largest fish. Ocean acidification affects many organisms in the sea. For example coral reefs are highly sensitive to changes in the pH of water and can become 'bleached' if the water becomes too acidic. In areas where whale sharks rely on coral reef systems for food, for example in the waters off the west coast of Australia, this could result in there being less food for whale sharks.