12 Things You Need To Know About Octopus, Squid & Cuttlefish
You find them in every ocean, in every marine environment. They come in all shapes and sizes. They have been around for more than 490 million years. They are the cephalopods - octopus, squid, cuttlefish, sepiolids and nautilus. Douglas David Seifert celebrates one of the ocean's most successful life forms. Here are 12 fascinating facts…
1) Cephalopods survived the Permian-Triassic extinction event which killed off 95% of marine life and the Cretaceous extinction which eradicated 90% of all existing animals.
2) Coleoid cephalopods (octopus, squid, cuttlefish & sepiolids) have three hearts and transport oxygen in their bloodstream via copper-based hemocyanin - making them true blue bloods.
3) In the cold and perpetual blackness of the deep sea, the eggs of the Graneledone boreopacifica octopus take four-and-a-half years to develop, making it the longest known incubation in the animal kingdom.
4) Octopus are the only cephalopods to tend their eggs until they hatch: squid, cuttlefish, bobtail squid and nautilus deposit their eggs and never look back.
5) More than 11,000 different species of cephalopods have been identified in the fossil records dating back nearly 500 million years.
6) Octopus, squid, cuttlefish and sepiolids can change their skin colouration in 200 milliseconds - a fraction of a blink of an eye.
7) Bigfin reef squid have the fastest growth rate of all cephalopods, growing as much as 600 grammes in a four-month growth spurt.
8) The nautilus is the only cephalopod that retains an external shell. They remain relatively unchanged from their first appearance 360 million years ago; a so-called ‘living fossil’ – with the six remaining species found in the Indo-Pacific.
9) Octopus have the largest brain-to-body mass ratio in the invertebrate world, larger than many vertebrate species.
10) The heaviest of all invertebrates is the colossal squid (Mesonychoteuthis hamiltoni) which can tip the scales at 495kg. And a cephalopod is also the longest invertebrate as the giant squid (Architeuthis dux) can reach a length of 12m.
11) Cephalopods are increasingly being targeted for food. The global catch of cephalopods is 4.8 million tonnes (3.5 million tonnes of squid and 350,000 tonnes of octopus) with a commercial value of USD$10 billion.
12) Size dimorphism between the larger female and smaller males is common among cephalopods.