Simplify the following text for a Grade 10 native English-speaking person.
Original: Joseph Eric Thornton ( born July 2 , 1979 ) is a Canadian professional ice hockey center and alternate captain for the San Jose Sharks of the National Hockey League ( NHL ) .
Simplified: Joseph Eric Thornton ( born July 2 , 1979 ) is a Canadian professional ice hockey center and captain of the San Jose Sharks of the National Hockey League ( NHL ) .