Candida albicans is the most commonly isolated species, and can cause infections (candidiasis or thrush) in humans and other animals. In winemaking, some species of Candida can potentially spoil wines.
Killer whales have no natural predators (they are the top predators of the oceans) and can live to about 50-80 years old. Killer whales have been hunted by humans but not with enthusiasm as it takes 21 killer whales to produce the same amount of oil as 1 sperm whale.
Whales are mammals because they give birth to live young, they have fur (although it is very sparse on their body), they have lungs and breath air and they provide milk for their young. You have a lot of interesting questions about marine mammals. Dolphins and other whales are all mammals called cetaceans.