Australian box jellyfish (Chironex fleckeri) This variety is the largest box jellyfish in the world and is considered the most venomous creature in the oceans. (more) What Is the Most Venomous Jellyfish? Ask the Chatbot a Question More Actions Share Share Share to social media Facebook X URL https://www.britannica.com/animal/What-Is-the-Most-Venomous-Jellyfish Feedback Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login). Feedback Type Select a type (Required) Factual Correction Spelling/Grammar Correction Link Correction Additional Information Other Your Feedback Submit Feedback Thank you for your feedback Our editors will review what you’ve submitted and determine whether to revise the article.

　　External Websites Ask the Chatbot a Question Written by The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... The Editors of Encyclopaedia Britannica Last Updated: Sep 18, 2025 • Article History Table of Contents Table of Contents Ask the Chatbot The Australian box jellyfish, scientifically named Chironex fleckeri, is widely considered the world’s most venomous jellyfish. Its highly potent venom can induce intense pain, paralysis, cardiac arrest, and death within minutes of a sting. Immediate medical attention is often required to prevent fatal outcomes. More than 70 deaths have officially been attributed to stings from the Australian box jellyfish in the last 100 years. The actual number may be higher because of underreporting in some regions. Governments in affected areas often issue warnings and implement safety measures to protect swimmers and beachgoers. About 50 species of box jellyfish have been ...(100 of 211 words)

　　Continue reading with Britannica Premium The trusted destination for facts and information 7-Day Free Trial, No Ads, Unlimited Access Subscribe Today