The Ultimate Creature in Impossible Creatures: Creature Chaos

An Electric Eel from unmodded Impossible Creatures.
http://img4.wikia.nocookie.net/__cb20111016005921/ichive/images/c/cc/ElectricEel.png

A Diplodocus from the Creature Chaos Mod.
http://img2.wikia.nocookie.net/__cb20111016020707/ichive/images/e/e6/Diplodocus.png

In the Creature Chaos mod for Impossible Creatures, you may have been looking for the ultimate combination... Look no further! I have the ultimate hybrid!

Introducing... the Electric Diplodocus!

This is a combination of the Electric Eel from the normal game and the Diplodocus from the Creature Chaos mod. For the most useful unit, give it all Diplodocus parts except for an Electric Eel head and torso. The torso will allow it to swim and the head will allow it to shoot its powerful electricity attack. Ranged attacks get stronger depending on the size of your creature too, so having the great Diplodocus will make the range do much more damage. The Diplodocus tail will also give it pretty good melee damage and the legs give it the ability to go on land.

If you want a prettier appearance that still is pretty useful, use all Diplodocus except the Electric Eel head and tail. It will still have a powerful range and can swim, but it will no longer have a good melee.