todropscience:

A NEW ORGAN DISCOVERED IN RABBIT FISH

Chimaeras are cartilaginous fishes (Chondrichthyes) known informally as ghost sharks, rat fish, spookfish  or rabbit fish. These fishes one time were diverse and abundant (based on the fossil record) now, their closest living relative are sharks. Holocephalan fish are specialized for durophagy; their upper jaw is fused to the neurocranium, and all  species  possess toothplates. 

The rabbitfish (Chimaera monstrosa) is a deep-water holocephalan  distributed  along  the Eastern  Atlantic, from  Morocco  to  northern  Norway  and Iceland,  and  in the Mediterranean.

Now scientists describe for the first time a new organ localized in the palate of the rabbitfish, named palatal organ. Attention has been paid to the holocephalan head morphology, but there has been no mention of this particular organ in the literature. 

The presence of a palatal organ has been demonstrated in many published images of chimaeroid  fishes,  but  has  gone  unnoticed.

Imagen: Specimen of C. monstrosa from the “Museum of Comparative Anatomy”—University of Genoa. (a) The jar containing the skull and vertebral column with some amount of soft tissue. (b) A detail of the jar with the label. © The palatal organ photographed through the glass.

The robust innervation but low density of taste buds suggest a role in gustation for the Palatal Organ, but primary utility in general mechanical sensitivity likely implicated in food sorting. The presence of numerous multicellular serous glands in the anterior/dorsal part of the Palatal Organ is quite surprising, probably these glands could include food lubrication, digestion and defense against pathogens.

• Reference: Ferrando et al. 2015 First description of a palatal organ in Chimaera monstrosa (Chondrichthyes, Holocephali). The Anatomical Record. The Anatomical Record. in press
• First Photograph: Chimaera monstrosa by Mandy Lindeberg,