Cryothenia amphitreta is a species of marine pelagic fish belonging to the family Nototheniidae (cod icefishes). It is found in the Antarctic Ross Sea. It has an unusual body structure: the pelvic fins reach only halfway from the pelvic-fin base to the anal origin, and the second dorsal-fin insertion is particularly advanced compared to the anal origin. C. amphitreta is coloured purple-gold with black linings on the mouth, gills cavities and peritoneum.
Cryothenia amphitreta Wikipedia
The species name is derived from Greek: Cryothenia means "from the cold" and amphitreta means "a cave with two openings".
Cryothenia amphitreta was discovered in 2004 and identified as a unique species of nototheniid fish. It has two openings in its cranium that allows it to detect changes in water pressure as small as another fish swimming by. Other nototheniid are known to have this same structure, but with only one opening. Having two pressure-sensing cavities may help the fish locate prey better.