Cepho Facts

A Male ^

The colossal squid (Mesonychoteuthis hamiltoni) is the biggest known invertebrate in the world, and has the largest eyes of any known creature.

Using jet-propulsion some squids in the Ommastrephidae family are able to launch themselves out of the water. By a combination of this jet-propulsion and spreading their arms and fins they are able to glide for long distances.

There are 2 main divisions of octopi; Cirrate octopus have 2 fins on their heads and have small hair like strands on their single row of suckers called cirri, Cirrate octopus also lack ink sacks and are deep sea dwelling.

You can see the fins on this dumbo octopus (Grimpoteuthis)

Incirrate octopus are the "stereotypical" octopus, they lack cirri on their suckers, and lack the fins on their head, but have ink sacks.

And you can see the lack of head fins on this Blue ringed octopus (Hapalochlaena)

The word cephalopod originates from the Ancient Greek words κεφαλή (kephalē, head) and ποδός (podós, feet). Cephalopods were named "head-feet" in reference to the simple looking body of a head connecting to their arms.

Although octopi (octopuses?) are normally solitary animals, there are a few examples of them grouping together and demonstrating complex social behaviours such as "Evicting members from their dens, and excluding individuals from the site."

Cephalopods are the only class of molluscs who have a closed circulatory system, aka their blood is kept within blood vessels.

The common octopus has about 500 million neurons, but interestingly, about two thirds of those are found in their arms. This gives their arms somewhat of a mind of their own.

Cephalopods (class Cephalopoda) can be subcategorized into 3 subclasses; Nautiloidea (Nautilus), Coleoidea (which contains all shell-less cephalopods), and the extinct Ammonoidea (Ammonites).

The vampire squid (Vampyroteuthis infernalis, aka "Vampire squid from hell") is actually more closely related to octopi than it is to squid.

Cephalopods use small organs called Chromatophores to change colours. Chromatophores contain small sacs of pigments, when the muscles surrounding the chromatophores stretch, they cause the pigment to expand under the skin and make the colour visible.