How many hearts does an octopus have?
An octopus has three hearts: two pump blood through the gills and one pumps it to the rest of the body.
Reference: Royal Danish Collection
An octopus has three hearts: two pump blood through the gills and one pumps it to the rest of the body.
A narwhal's tusk is actually a tooth that grows through its upper lip, and it's usually found on males.
About two-thirds of an octopus's neurons are in its arms, so each arm can sense and react somewhat independently of the brain.