Megalograptus is a water dwelling eurypterid. It appeared in Dangerous Seas.
Similar to it's successor the Megalograptus has a similar body shape and large claws. It's tail was not filled with vdenom but instead it had claws to grab prey. It also had numerous smaller protrusions on it's body most likely to protect itself.
It has very prominent role in the first half of the epsiode mentioned earlier. It even attacked Nigel during the episode.
- During Dangerous Seas Nigel never called them by name. Infact their name is never mentioned.