Five minutes of googling around does the job...

"Lessepsian Migration
The term lessepsian, is derived from Ferdinand De Lesseps who designed and led the team that built the Suez Canal, thus linking the Red Sea with the Mediterranean. Lessepsian migration refers to species which have entered the Mediterranean, from the Red Sea, through the Suez Canal. Some of these introductions seem to be permanent, some short-lived.
For those of you interested in exotic introductions to the Mediterranean, there is a website CIESM Atlas of Exotic Species in the Mediterranean Sea which has a list of introduced molluscs, including quite a few opisthobranchs. There is a comprehensive page on each species, but unfortunately no photos."

Driven by: Richard Piper (GB)/Ferdinand de Lesseps (F)/Olindo Iacobelli (USA)