Giant Squid and Colossal Squid Fact Sheet

This article is in the series Concerning Giants
An analysis of the size of the largest cephalopods: Architeuthis and Mesonychoteuthis

Authored by Dr. Steve O'Shea and Dr. Kat Bolstad

Steve and Kat are members of the TONMO staff. You can communicate with them both in our Cephalopod Science forums.


To ensure accurate reporting of these squid species, the following brief notes have been prepared. First, a simplified account of squid morphology (Fig. 1), where we detail the differences between squid and octopus; second, an introduction to size and how it has been measured (and misreported); and third, an introduction to the two species that you will be hearing a lot about: Colossal Squid (Mesonychoteuthis hamiltoni) and Giant Squid (Architeuthis dux).

We already have online an introduction to octopus and squid anatomy in our article, Deep-Sea Cephalopods: An Introduction and Overview, so will not unnecessarily duplicate that information. For the sake of this article we will focus on the absolute basics of cephalopod anatomy, and some frequently cited measures, particularly Mantle Length (ML), Standard Length (SL), and Total length (TL).

1. Introduction to squid anatomy: Basic squid and octopus facts

A basic squid has:
  • Two fins
  • A mantle
  • A head
  • 8 arms and two tentacles, each endowed with hooks and/or suckers and sucker rings (Figs 1—4)
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About the Author
Steve O'Shea
Steve is an expert in the systematics and biogeography of cephalopods, and joined the staff in June 2002. He can be seen on the Discovery Channel documentary, Chasing Giants: On the Trail of the Giant Squid. For more information, see his Autobiography and Select Bibliography (2003). Dr. O'Shea lives in New Zealand.


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