Torrance-based Knowledge Adventure, which owns the JumpStart brand of educational software titles, said Thursday that it has launched a new virtual world targeted at 5 to 8 year olds. According to the firm, the world--called MarineLand--is an extension of its existing JumpStart 3D Virtual World. JumpStart has been building up a portfolio of online, virtual worlds targeted at various age groups, including one for 3-5 year olds, another for 5-8 year olds called AdventureLand, and also has plans for one targeted at 8-12 year olds. All of the worlds are accessible as part of a single, $7.99 monthly plan for a family.