Males monk seals can reach around 7 ft (2.1 m) in length while females grow larger to around 8 ft (2.4 m). Females can weigh up to 600 lbs (270 kg). Female monk seals carry their babies for 10 to 11 months. At birth, a monk seal pup will already be over 3 ft (.9 m) in length. Male monk seal can be quite aggressive.