Dolphin fact #11
A mature Dolphin will give birth every 2 to 3 years and have as many as eight birth cycles in a lifetime. They are able to give birth at any time of the year but it is most common for calves to be born in the spring or summer. The females are able to mature sexually at 8 years of age. Of notable fact is that Dolphins, humans, and bonobo chimps are the only creatures that have sexual intercourse for pleasure, rather than just for reproductive purposes.
Dolphin fact #12
Unlike most marine animals, Dolphins lack nostrils so they have to surface every 15 to 20 seconds to clear their blow holes with a burst of air. They can commonly dive 200 meters and can remain underwater for 8 to 10 minutes by slowing their heart beat and controlling their blow flow. Unlike humans, Dolphins only breathe voluntarily rather than automatically, so if they are knocked unconscious they stop breathing.
Dolphin Fact #13
The greatest natural predators of Dolphins are humans. Dolphins often get caught in fishing nets or are caught intentionally to be eaten in such dishes as Dolphin steak. The second most dangerous predator to Dolphins are sharks, especially in areas surrounding South Africa and Australia. The third most dangerous predator to Dolphins are, well, other types of Cetacea (the family which includes Dolphins). Orcas, also known as killer whales, quite often eat fish, other whales, and smaller marine mammals such as Dolphins.
Dolphin Fact #14
Because the ocean is so salty, most Dolphins cannot drink from it, as the salt would instead dehydrate their bodies. Instead, most of the water a Dolphin recieves comes from the bodies of the fish and squid it eats. Quite often, the moisture content of a Dolphin's food is in excess of 80%. A Dolphin does not require very much water, as it's skin is impermeable to water, and a Dolphin does not lose water by sweating like humans do.
Dolphin Fact #15
Most Dolphins can hear sounds in excess of 150Khz frequencies. This is very much higher than the 22 Khz range audible to humans. Although dolphins can hear frequencies this high, they typically only produce sounds in the 1.5-11.0 Khz range. They use these sounds in order to communicate with other Dolphins, find food, signal mating interest, or warn other Dolphins of danger.