Jet Squid are creatures that appear in The Drowned Vault. Their flesh is toxic. For every pair of them one is male and one is female. The males have red dots on their beaks but females don't. Jet Squid chage genders quite often. The males blow hydrogen out of their beaks. The females blow oxygen out of their beaks. They can extend a dive for a long time as shown in The Drowned Vault when Rupert Greeves and Cyrus Smith use them to reach the burial of John Smith.