Walking With Wikis

Cruel Sea
General information
SeriesWalking with Dinosaurs
Episode number3
Featured creaturesOphthalmosaurus pups
Broadcast information
Original airdate18 October 1999
Chronological information
Previous episode
Time of the Titans
Following episode
Giant of the Skies

Cruel Sea - broadcast in North America as Jurassic Beach - is the third episode of Walking with Dinosaurs.

An Ophtalmosaurus and a prehistoric Jellyfish

Full synopsis

The episode begins with a Eustreptospondylus being snatched from the shore by Liopleurodon. Meanwhile, hundreds of Ophthalmosaurus arrive from the open ocean to give birth. Hybodus and a Liopleurodon are on the hunt; when a mother Ophthalmosaurus has trouble giving birth, a pair of Hybodus pursue her. They are frightened off by a male Liopleurodon, which eats the front half of the ichthyosaur. Meanwhile, a Eustreptospondylus swims to an island and discovers a turtle carcass; it fights over the carcass with another Eustreptospondylus. Later, during the night, a group of horseshoe crabs gather at the shore to lay their eggs, which attracts a flock of Rhamphorhynchus in the morning to eat the eggs. However, a few of the pterosaurs are caught and eaten by a Eustreptospondylus. While the Ophthalmosaurus juveniles are growing up, they are hunted by Hybodus, which in turn, are prey for the Liopleurodon. While the male Liopleurodon is hunting, he encounters a female Liopleurodon; after the male bites one of her flippers, she retreats from his territory, and a group of Hybodus follows the trail of her blood. A cyclone strikes the islands, killing many animals, including several Rhamphorhynchus and the Liopleurodon, who is washed ashore and eventually suffocates under his own weight. A group of Eustreptospondylus feed on his carcass. At the end of the episode, the juvenile Ophthalmosaurus that survived the storm are now large enough to swim off and live in the open sea.

In the credits, it is stated that even though only turtles remain, marine reptiles were a glory of their age and that another group shared the dinosaur's world, the flying pterosaurs; which are claimed, as the next episode would show, to be just as spectacular.


149 Million Years (Oxfordshire, England)

  • The Eustreptospondylus we can see in the episode.

    (first appearance)
  • Liopleurodon
  • Cryptoclidus (first appearance) (Identified as plesiosaurs in Walking With Dinosaurs : Short Bites)
  • Leptolepis (unidentified in episode, revealed on website, live acted by herring, only appearance)
  • Perisphinctes (unidentified in episode, revealed on website, identified as Ammonite)
  • Jellyfish (first appearance)
  • Ophthalmosaurus (first appearance)
  • Cylindroteuthis (live acted by squid, first appearance)
  • Rhamphorhynchus (first appearance)
  • Hybodus (unidentified in episodes, revealed on website, Sea Monsters and encyclopedia, identified as Shark, first appearance)
  • Sea turtle carcass (first appearance)
  • Bark beetle (first appearance)
  • Mesolimulus (identified as, and live acted by, horseshoe crabs)

A group of Ophtalmosaurus.

Alternate Versions

  • In a rerelease, several scenes are either rearranged or cut:
    • The scene where the Liopleurodon ambushes a Eustreptospondylus is moved from the opening to the middle of the episode.
    • The introduction to Liopleurodon is shortened.
    • The Cryptoclidus, Rhamphorhynchus and horseshoe crab scenes are cut.
    • The scene where two Eustreptospondylus fight over a turtle carcass is cut.
    • The storm scene is cut, rearranging the ending with the female Liopleurodon beaching herself after becoming disoriented from blood loss from the wound inflicted by the male.
  • In a rerelease, the Ophthalmosaurus pups are the ones hunting squid instead of the adults.
  • Implication of cannibalism in Ophthalmosaurus is omitted in the US dub.
  • In the US dub, the Liopleurodon is introduced before he attacks the pregnant Ophtalmosaurus.
  • In the UK dub, the storm is a natural tropical storm. In the US dub, it is an earthquake caused by the movement of the continents.
  • In the US dub, the juvenile Ophthalmosaurus are never shown leaving the reef, implying they've either been killed or survived offscreen.


  • This episode is the only episode which focuses primarily on aquatic life.



  • Liopleurodon was not 25 metres long and was not 150 tonnes. The largest Liopleurodon skeleton is 6 to 7 metres long and 2 tonnes.
  • Liopleurodon couldn't catch Eustreptospondylus. A creature of this size would have washed up on the reef.