List: word usually written using kana alone

usually written using kana alone  noun  noun (generic) 

• sloth bear (Melursus ursinus)

usually written using kana alone  noun  noun (generic) 

• spectacled bear (Tremarctos ornatus)

usually written using kana alone  noun  noun (generic) 

• ocellated octopus (Octopus ocellatus)

usually written using kana alone  noun  noun (generic) 

• greater argonaut (species of paper nautilus, Argonauta argo)

usually written using kana alone  noun  noun (generic) 

• winged argonaut (species of paper nautilus, Argonauta hians)

usually written using kana alone  colloquial  noun  noun (generic) 

• eggcase (shell) of the winged argonaut
• winged argonaut (species of paper nautilus, Argonauta hians)

rarely used kanji form  usually written using kana alone  noun  noun (generic) 

• blue-ringed octopus (esp. the blue-lined octopus, Hapalochlaena fasciata)

usually written using kana alone  noun  noun (generic) 

• giant Pacific octopus (Enteroctopus dofleini), North Pacific giant octopus

usually written using kana alone  noun  noun (generic) 

• long-armed octopus (Octopus minor)

rarely used kanji form  usually written using kana alone  noun  noun (generic) 

• brown hawk owl (Ninox scutulata)