Dolphins have exclusive way to use their eyes independently. It happens because their brains are separated into two different ways, which allow their one eye to rest while the other is open to watch for danger for the possible attack of predators such as sharks. One reason why they want to sleep is to acquire energy. At times they sleep with both eyes close and that is about 20% of the time.

How do they sleep?

Based from the study of Williams et al, 1990, dolphins are conscious with their breath. This mean they cannot appear to have a full deep sleep, because they would probably suffocate. So they need to get into the surface to breath. This has been determined by EEG examination, they sleep about 8 hours a day. Recent research confirmed that dolphins have only one eye closed when sleeping and remain constant for an hour, after which it switches with the other eye again.

Rapid Eye Movement (REM) usually associated by dreaming is only a rare case. Some scientist claims that dolphins do not have REM sleep at all.

A dolphin’s behavior like resting and sleeping depends on the condition and possibly of character preferences. They can swim slowly and surface every now and then for a breath, they can rest at the surface with their blowhole exposed, or on the bottom (in shallow water) and rise into the surface every so often to catch up breath.

Did you know that twins can have different father?

Every month a woman’s ovary releases one egg that can be fertilized by one sperm. But in this case, a pair of eggs emerged. Based from the scientific explanation, sperm can remain alive inside the reproductive tract of women for 5 days, in this way; she can have sex with different man within those days. That will cause fertilization of two or more ova by spermatozoa of different males.

This rare occurrence happened in Texas when a 20 years old woman gave birth of 2 handsome twins with different father on the year 2009. The secrecy began when his partner became concerned of their twins for they looked so different. A paternity test followed. When truth came that the one child is not his son, he was hurt but since he loved the twins since then, he decided to raise the child all the way until now.

How it is proven?

A DNA paternity test is performed in order to come out with the answer. This phenomenon is rarely case documented in the world and it is known as hetereopaternal superfecundation. It is derived from the word “fecund” meaning the ability to produce offspring. It happens within hours or days of the first instance of fertilization. Ovulation is stop during pregnancy to prevent further ova to become fertilized and to help to have a full term pregnancy. However, if the ovum is released after the impregnated, there is a second chance of pregnancy.