Complex sentence: Pacific sleeper sharks are believed to produce eggs that hatch inside the female's body (reproduction is ovoviviparous), but gestation time is unknown and litter sizes are thought to be about 300.
Split into simpler sentences: Pacific Sleeper Sharks are believed to produce eggs that hatch inside the female's body (Reproduction is ovoviviparous), but gestation time is unknown. While litter sizes are thought to be about 300.