Jellyfish belong to the Phylum Cnidaria and Class Scyphozoa, or 'true jellies'. Occasionally species in other Cnidarian Classes may also be referred to as jellyfish.
Jellyfish, so called because of their jelly textured invertebrate bodies, are almost exclusively marine animals. They are simply structured, typically consisting of a bell-shaped body with tentacles, and one orifice through which to eat and expel waste.
In the How to Train Your Dragon Book Series, jellyfish are mentioned as descriptors and in exclamations.
In reality, jellyfish are occasionally eaten. They are also potentially dangerous to humans due to their stings and can occasionally disrupt fishing.
The character Fishlegs No-Name is described as having "a squint that made him as blind as a jellyfish and an allergy to reptiles."
Fishlegs also uses jellyfish in an expressive exclamation.
|“||Well, jigger my jellyfish||”|
Hiccup mentions jellyfish when describing himself in a negative way.
|“||I have about as much charisma as a stranded jellyfish and yelling is just another thing I'm useless at.||”|
|“||YOU ARE NOT AN ICKLE PRETTY JELLYFISH ...||”|
|— Gobber in Book 2|
During an 'Advanced Rudery' lesson, Snotlout spars with Tuffnut Junior at hurling insults.
|“||You ... are a cowardly cowering cuttlefish ... with the heart of a jellyfish, the brains of a plankton, and the stink of a barrelful of mackerel heads.||”|
|— Snotlout to Tuffnut Junior in Book 2|
Fishlegs again uses 'jellyfish' in an exclamatory phrase in Book 3.
|“||Ooooh, jumping jellyfish||”|
|“||I ALWAYS KNEW YOU WERE A FAT BURGLAR AND AN HEIR-STEALER, BUT I NEVER KNEW YOU WOULD RUN AWAY LIKE A COWARDLY JELLYFISH!||”|
|— Book 3|
As with the previous books, jellyfish is used in exclamation.
|“||Oh jumping jellyfish.||”|
|— Hiccup in Dragonese|
Jellyfish are used metaphorically by Fishlegs when - in his berserker state - he insults Gobber the Belch by comparing his intelligence to that of sheep and jellyfish.
|“||I'VE MET SHEEP MORE INTELLIGENT THAN YOU ARE! I'VE MET JELLYFISH WHO COULD OUTPLAY YOU IN A GAME OF CHESS!||”|
|— Fishlegs to Gobber in Book 4|
A jellyfish's lack of a rigid structure is referenced after an encounter with a Doomfang.
|“||Hiccup clambered out of the sleigh, his legs wobbling like jellyfish.||”|
|— Book 4|