Professor Geoffrey Isbister Clinical toxicologist , Calvary Mater Newcastle and NSW Poisons Information Centre ; professor , University of Newcastle , NSW .

First published online on 2 February 2024

INTRODUCTION

MARINE creatures are responsible

for a range of venomous and poisonous

effects in Australia . Venomous animals have a specialised gland that produces venom , which is injected into or applied to another organism causing envenoming , such as a sting from a jellyfish . Marine poisoning occurs when a marine creature containing toxic substances is ingested . These marine creatures do not contain a specialised venom apparatus . The major groups of venomous marine creatures are jellyfish , which cause stings when their tentacles contact skin , and spiny venomous fish causing penetrating injuries . Most marine stings are uncommon — except for bluebottle stings , which have been experienced by many Australians . Other marine stings include sea urchin spine injuries , contact reactions to sponges and , rarely , blue-ringed octopus and sea snake bites .

Ciguatera is the most common type of marine poisoning from eating particular reef fish and is a major issue in the Pacific . Other marine

poisonings are uncommon and include tetrodotoxin poisoning , shellfish poisoning and scombroid . 1

This How to Treat covers marine envenoming and poisoning . It aims to ensure GPs can treat common marine bites and stings and know when to refer more complex cases .

MARINE STINGS AND ENVENOMING

Epidemiology

MARINE stings generally occur in

the warmer months when swimming is popular — except in the tropics , where they can occur throughout the year . They are a common presentation in coastal hospitals and medical practices , ranging from very minor jellyfish stings to severe box jellyfish envenoming and major trauma from stingray injuries .

Most jellyfish stings are minor , such as bluebottle stings ; people often do not seek medical attention and are treated by surf lifesavers or first-aid stations . Severe injuries are rare and include major box jellyfish and stingray injuries . These require urgent medical treatment .

Jellyfish stings

Jellyfish belong to the phylum

Cnidaria and include a large variety of marine creatures , with more than 100 medically important species . Most patients do not easily recognise jellyfish , with the exception of common species , such as the bluebottle ( Physalia physalis ). Most stings cause similar effects , making it difficult to associate clinical effects with a particular jellyfish .

Important jellyfish in Australia include bluebottles ( Physalia sp .); major box jellyfish ( Chironex fleckeri ); Carukia barnesi , which causes Irukandji syndrome ; and a range of other minor jellyfish , such as hair jellyfish ( Cyanea sp .), mauve stinger ( Pelagia sp .), jimble and other box jellyfish ( Chiropsalmus bronzeii ).

The envenoming apparatus of jellyfish are called nematocysts or stinging cells . These occur in large numbers on the tentacles and cause most stings , such as in physalia stings . However , there are small numbers on the bell , and these are important in envenoming in some species , such as C . barnesi , which causes

Irukandji syndrome . The nematocysts contain venom and a coiled hollow harpoon-like tube that will spring out when stimulated , penetrating the skin of the victim and injecting venom .

There are two major clinical syndromes that result from venom injection with jellyfish stings : linear tentacle-like stings and Irukandji-like stings , where contact with the bell is more likely ( see box 1 and table 1 ). Most jellyfish stings are the former , with varying severity of pain and sometimes with non-specific systemic effects .

Bluebottle stings

Bluebottles ( see figure 1 ) are the most

common cause of jellyfish stings in Australia and account for thousands of stings annually — mostly in NSW and Queensland . Most cases are treated on the beach or at home ; very few cases present for medical treatment .

CLINICAL EFFECTS Bluebottle stings cause immediate intense local pain where the