The difference between venomous and poisonous marine animals

The terms ‘venomous’ and ‘poisonous’ tend to be used interchangeably. While they generally refer to animals that produce a toxin that can harm another animal, the difference lies in how the toxin is delivered.

Venomous animals inject venom into other animals, for example, through bites or stings. Poisonous organisms are harmful only when eaten or touched – the toxin needs to be ingested or absorbed.

Now that we have cleared the air, let’s take a look at 4 venomous and poisonous sea creatures found at S.E.A. Aquarium:


Crown-of-Thorns Sea Star

crown of thorns 2

They may be one of the biggest sea stars in the world, but don’t get too close to them when snorkeling or scuba diving. Their upper surface is covered with thorn-like spines that inject venom containing asterosaponins into the victim’s body when pricked. The result is hours of unbearable pain, constant bleeding, nausea and swelling.

Click here to read more about the Crown-of-Thorns and other sea stars


Black botched stingray pup
Black blotched stingray pup

While generally non aggressive, stingrays have been known to whip up the barbs in their slender tail when they feel threatened, such as when swimmers and divers accidentally step on them.

These barbs contain venom and are sturdy enough to penetrate wetsuits and rubber boots. Victims will experience excruciating pain, and at times nausea, vomiting and muscle cramps too.

Click here to learn about Black Blotched Fantail Rays, a type of large stingrays, that were born at the S.E.A. Aquarium.



This pufferfish is one of our aquarium residents. Picture by Boon Ping, aquarist at S.E.A. Aquarium

The flesh of the pufferfish contains tetrodotoxin which makes it taste awful and often lethal to fish. Tetrodotoxin is also deadly to humans if ingested, and even more lethal than cyanide. In fact, a single pufferfish has enough poison to kill 30 adult humans, and there is no known antidote.

Amazingly, the pufferfish is considered a delicacy in Japan. Called fugu, it is extremely expensive and only qualified chefs are allowed to prepare the dish, as one wrong cut may mean death for the customer.

In 2013, a new species of pufferfish was found creating underwater masterpieces as part of their courtship ritual. Read all about it here.

Longhorn Cowfish

cowfish featured

It may look adorable but when it is stressed, it is anything but cute. The Longhorn Cowfish releases a neurotoxin called ostracitoxin from the cells under its skin when it feels threatened or when faced with potential predators.

But here’s the best part: not only is this toxin lethal enough to kill other tank inhabitants, it may even kill itself. Here are more here for more fun facts about the Longhorn Cowfish.

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