Cephalopods are incredibly evolved creatures: The Giant Squid has three hearts that pump blue blood. Food travels through its brain before reaching the stomach and they utilise floating bones to detect gravitation for orientation in the dark.

All cephalopods (octopuses, squid, cuttlefish and nautiluses) have three hearts: two branchial hearts and one systemic heart.
The two branchial hearts pump blood to the gills, where oxygen is taken up. Blood then flows to the systemic heart, where it is pumped to the rest of the body.
A cephalopods blood contains the copper-rich protein hemocyanin which transports oxygen and tints the squid’s blood blue. Human blood instead contains the iron compound haemoglobin which gives our blood its bright red colour.

The three hearts ensure enough oxygen supply for the Squids body and its internal organs.
These molluscs have to cut up food into small chunks so it can travel through the squid’s oesophagus, an extremely narrow digestive tract, which leads from the beak through the middle of the squid’s brain to its stomach.

The brain is shaped liked a doughnut and surrounds the narrow oesophagus. It is very small in comparison with the overall size of the body — a 300 kg colossal squid has a brain weighing less than 100 gram!

Squid and octopus have an intricate nervous system, more complex than other molluscs, and invertebrates in general.
The squid brain is enclosed in a cartilaginous head capsule and includes two large optic lobes. These indicate that vision is very important to squid. Up to 80 per cent of the brain is devoted to processing visual information.

Squid can tell how they are positioned in the water.
This information is provided by two statoliths located within the squid’s brain. Each statolith is a small calcareous structure which sits within a chamber called a statocyst. As the little bone moves around within the chamber, the squid can apply this information to gravity and work out which way is up in the dark.
Statoliths are composed of a changing structure of daily added supplements (much like annual tree rings). Scientists utilise this information for assessing age, growth rates and hatch dates of key species.

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