An ecosystem with a large number of species is said to have

Biodiversity

Explanation:

Biodiversity deals with how specie rich an ecosystem is. An ecosystem with a large number of specie can be said to be bio-diverse i.e it has a wide variety of species.

The tropical regions of the world can be said to be bio-diverse in that a wide variety of species inhabit them.

the electromagnetic spectrum includes, from longest wavelength to shortest: radio waves, microwaves, infrared, optical, ultraviolet, x-rays, and gamma-rays.