Tetrodotoxin, frequently abbreviated as TTX, is a potent neurotoxin. Its name derives from Tetraodontiformes, an order that includes pufferfish, porcupinefish, ocean sunfish, and triggerfish; several species that carry the toxin. Although tetrodotoxin was discovered in these fish and found in several other animals (e.g., blue-ringed octopus, rough-skinned newt, and Naticidae) it is actually produced by certain symbiotic bacteria, such as Pseudoalteromonas tetraodonis, certain species of Pseudomonas and Vibrio, as well as some others that reside within these animals.

Tetrodotoxin inhibits the firing of action potentials in nerves by binding to the voltage-gated sodium channels in nerve cell membranes and blocking the passage of sodium ions (responsible for the rising phase of an action potential) into the nerve cell.

TTX is extremely toxic. The Material Safety Data Sheet for TTX lists the oral median lethal dose (LD50) for mice as 334 μg per kg. For comparison, the oral LD50 of potassium cyanide for mice is 8.5 mg per kg, demonstrating that even orally, TTX is more poisonous than cyanide. TTX is even more dangerous if injected; the amount needed to reach a lethal dose by injection only 8 μg per kg in mice.

Naticarius orientalis

…is a colorful species of moon snail (Naticidae) that can be found throughout the waters of the Pacific. Like other moon snails N. orientalis is a predator and fees mainly on bivalves and other shelled molluscs. Once N. orientalis finds a prey item it will envelop the prey and bore a hole into its shell using its radula and a secretion. Once the hole is made it will insert its proboscis into the hole and consume it.


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Image: Nick Hobgood

#769 - Fam. Naticidae - Moon Snail Attack

A clear sign that there are Naticids about. Moon Snails (also known as necklace shells) are large round predatory sea snails, common on sandy shorelines, that hunt other molluscs.

After ploughing up the sand to find a prey item, the moon snail envelops the victim prey and then bores a hole through the shell using its radula and acid secretion. The damage to this Pipi is typical - a wide conical “countersunk” borehole with chamfered edges, near the hinge. Once the shell is bored open, the proboscis is used to consume the flesh.

In the breeding season, some species lay a rather stiff egg mass which includes sand and mucus.Washed up on beaches they’re known as “sand collars” because of their resemblance to an old-fashioned removable shirt collar. On the other hand, the moon snails around here lay semi-circular, clear gelatinous sausages known in the parlance as “shark poo”

Woodman Point. Perth

Natica hebraea

…is a species of moon snail (Naticidae) that occurs throughout European waters and in the Mediterranean sea. Like other moon snails N. hebraea is a predator and feeds mainly on bivalves, although they will attack other shelled molluscs as well. Once a prey item is sighted the snail will envelop the prey and bore a hole into its shell using an acid secretion and its radula. Once the hole is bored N. nebraea will insert its proboscis into the prey and consume it.


Animalia-Mollusca-Gastropoda-Caenogastropoda-Hypsogastropoda-Littorinimorpha-Naticoidea-Naticidae-Natica-N. hebraea

Image: Blenni