A sea lion with a net filament wrapped around its neck (Photo
Credit: Schusterman; Long Marine Laboratory, UCSC).
Sea lions are occasionally preyed upon by killer whales, great
white, hammerhead, and blue sharks. They are also known to have
such diseases as pneumonia, caused by a parasitic lungworm, and a
bacterial infection called leptospirosis, which affects their
livers and kidneys.