Fish with a "folding knife" in the cheek

Investigating several species of stone fish, some of the most poisonous fish, biologists find in them an unusual protective mechanism - a spike that usually lies on the cheek of the fish.

They call it a lachrymal saber spike in analogy to the lacrimal gland - acute bone growth develops from the sinuses located on the cheeks of the fish under the eyes.

Stone fish is a highly poisonous predator, met along the coasts of the Pacific Ocean and the Indian Ocean. The scabs on her body are covered with a powerful toxin that can kill a person for several hours. The fish is well hidden among the stones (which is why this species is known as "stone fish"), and its spikes can pierce a human shoe.

The phylogenetic relationships in the family of Scorpaenidae are also investigated when they notice that when a predator approaching these fish on their muzzle comes a threatening spike. Obviously, the predators know about this danger and often avoid them because of the threat of the spike being stuck in their mouth when they try to swallow their prey. In addition, the weapon can be used in intra-battle battles. Such adaptation is unique - nothing like this is the case with other fish.

Surprisingly, so far this unusual feature has remained unnoticed - this again shows how poorly this family of marine tropical fish has been studied. Richardson and her co-authors studied 63 stone fish, comparing their 113 physical parameters and 5280 plots in their genomes, specifying the phylogenetic relationships in the family. "The lazy saber" is found in all the representatives of the stone fish family.

Image Source:
Smithsonianmag