What sea creatures are lawful to consume without ritual slaughter (Dhabh)?

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Any creature that lives in the sea but also inhabits the land, such as water birds, turtles, and water dogs, is unlawful to consume without proper ritual slaughter (Dhabh). However, creatures that lack flowing blood, such as crabs, are permissible to eat without ritual slaughter. Imam Ahmad held that crabs are permissible and require no slaughter because the objective of Dhabh is blood removal, which is irrelevant for creatures without blood. Water dogs and leeches require Dhabh according to Imam Ahmad, and he permits the turtle if it is slaughtered. The ruling that all sea life is lawful without Dhabh is based on the narration concerning the sea stating, "Its water is purifying, and its dead creatures are lawful," and the saying of Abu Bakr as-Siddiq that God has made everything in the sea lawful. Imam Ahmad narrated, with his chain, that Shurayh said, 'Everything in the sea is slaughtered,' and a narration states the Prophet, peace be upon him, said, 'Indeed, God has slaughtered everything in the sea for the son of Adam.'