Everyone knows we have five senses. Some people may have six senses. A sixth sense could be knowing something without using the five senses of sight, hearing, smell, touch and taste. Researchers have discovered that some dolphins have seven senses. Dolphins can sense electricity produced by the heart beats of other sea creatures. This could help dolphins to find their next meal. This seventh sense may also help them to navigate using Earth's magnetic field. Dolphins also use their eyesight and sonar to sense what is around them.

The researchers conducted a study on two dolphins. Experiments tested what kinds of electricity the dolphins could detect. They sensed two kinds – direct current and alternating current. They were better at sensing direct current. All sea creatures produce direct current electricity. Being able to detect this means dolphins can sense how near other fish are to them. Dolphins could use this to hunt, even if they cannot see or hear well, or if they cannot use their other senses. The study has been published in a biology journal.