A Tribal member saw this on the beach in Saint Mary's, Alaska and has never seen one before; curious of what it is and if it can be an invasive species.
Derek Sikes, Curator of Insects University of Alaska Museum - Entomology, UAF, University of Alaska Fairbanks:
That's a larva of a predaceous diving beetle. Given its size I suspect it's in the genus Dytiscus. We have about 8 species of Dytiscus native to Alaska.
Comments by LEO editors
The adult to this larva, the Predacious Diving Beetle (photo below) spends most of its time in water feeding on other aquatic insects and creatures, even tadpoles. The male and female fly very well outside of the water, but the larvae are hatched in water bodies. They are ferocious predators and are aggressive by nature, for this reason they have the nick-name "Water Tiger." They are common in Alaskan lakes and ponds. More information can be found at insectIdentification.org. Chyna Perez-Williams
Predacious Diving Beetle Larva
Adult Dytiscus alaskanus, known generally as the boreal water beetle or Alaskan diving beetle, is a species of predaceous diving beetle in the family Dytiscidae. It is found in North America.