The Gift of Gab (short story)

"The Gift of Gab" is an early science fiction short story by American author Jack Vance, first published in 1955.

Mineral prospectors on another planet examine their environment more closely when crew members start to disappear.

But one of the scientists who is studying the marine species in aquariums begins to suspect that the decapods, a creature similar to a squid or nautilus with ten tentacles and eyes, may be smarter than an ordinary mollusc.

He attempts to teach a semaphore-like code, using the decapods's tentacles like hands of a clock to represent letters than can spell out English.

Meanwhile, the prospectors discover rich mineral deposits on the floor of the sea that can be easily mined, but at the cost of destroying the species.