Complex sentence: The male now lives forever as a parasite and degenerates, fusing himself with female's body and gains nourishment from her bloodstream, and eventually the male is just a pair of gonads, releasing sperm during the mating season.
Split into simpler sentences: The male now lives forever as a parasite and degenerates, fusing himself with female's body. He gains nourishment from her bloodstream, and eventually the male becomes just a pair of gonads, releasing sperm during the mating season.