Johan Hjalmar Théel

Johan Hjalmar Théel (14 June 1848 – 20 July 1937) was a Swedish zoologist and university professor.

He used to go on hunting trips along the coast of Norway in his youth and became fascinated by the plants and animals he encountered, especially the marine life.

He met the zoologist Sven Ludvig Lovén who sparked his interest in sipunculid or peanut worms, especially the genus Phascolion.

In 1875, he accompanied the explorer Adolf Erik Nordenskiöld to the mouth of the Yenisei River in an attempt to find the Northeast Passage.

He joined him on a similar voyage the following year and discovered a sea cucumber new to science, which he named Elpidia glacialis.