Octopuses

They have three hearts and blue blood, they squirt ink to deter predators, and are boneless. Yes, it's the amazing Octopus Exhibition.

Octopuses
image by arhnue

Octopuses are among the most intelligent and behaviorally diverse of all invertebrates with a complex nervous system and excellent sight. They have a closed circulatory system, in which the blood remains inside blood vessels. They have three hearts; a systemic heart that circulates blood around the body and two branchial hearts that pump it through each of the two gills.

Some people call their appendages tentacles, but that is incorrect; they are arms and two-thirds of an octopus’ neurons are in them, rather than in its head. This gives them something called a distributed intelligence. It means that an octopus can focus on exploring a cave for food with one arm while another arm tries to crack open a shellfish.

When scared, octopuses will shoot a dark liquid, sometimes called ink, at the thing that scared them. This will temporarily blind and confuse a potential attacker, giving the octopus time to swim away. The ink can also dull the attacker’s smelling and tasting abilities.