Up to 8 meters
Cryptoclidus was a medium sized Middle-Late Jurassic Plesiosaur, of a size of up to 8 metres (27 feet) long and 7-8 tonnes in weight.
It was a carnivore specialising, like all Plesiosaurs, on catching fish with snaps of its interlocking tooth lined jaws, using its small head to appear less intimidating and to ambush its fish prey. They could have also been agile pursuit predators, as is shown in Walking With Dinosaurs as they burst through shoals of fish at high speeds.
The relatively smaller size of these animals leads Palaeontologists to form comparisons between Cryptoclidus and Seals with, as seen in Walking with Dinosaurs, Cryptoclidus portrayed as basking on the shores and rockpools like seals - somewhat cumbersome on land but graceful acrobatic mariners when they hit the water. Cryptoclidus would have been a middling predator in the Jurassic Tethys Ocean - eaten by the even bigger marine reptiles, the Pliosaurs, such as Liopleurodon.