Grideye fish
Ipnops meadi, also known as the grideye fish, is a highly specialized species of Placodithyran abyssal fish found in the Clarion-Clipperton Zone of the Indo-Pacific Ocean. The species was named after Giles W. Mead of the Harvard Museum of Comparative Zoology, a biology professor at Harvard, deep sea explorer, and ichthyologist.
Since all three species of Ipnops are primarily distinguished by their geography, all three species have roughly the same physiology. All Ipnops are generally characterized as long and slender fish lacking traditional ocular lenses found on most marine organisms. In place of eyes, grideye fish have flat bony membranes on top of their skull which act as photosensitive plates. Ipnops also have large mouths, given their size, and sharp, pointed teeth on both the palatine and vomer regions of the mouth.
Based on the dissection of multiple samples, all species have roughly 13-15 anal rays, 13-15 pectoral fin rays, and 54-58 vertebrae. However, due to the species similarity, some scientists have suggested the Ipnops are hybrids and not reproductively isolated, or that Ipnops should just be a single species.
From collections and dissections of Ipnops species, there are a few characteristics specific to I. meadi, compared to the other two species, including:
Due to their rarity, and lack of photos, the three species of Ipnops (I. agassizi, I. meadi and I. murrayi) are distinguished by the depth and location of which they reside. I. meadi and I. agassizi are found in the Indo-Pacific Ocean, and I. murrayi are found in the Atlantic and Caribbean Sea. Ipnops agassizi, meadi, and murrayi also differ by which the depths they occupy. I. agassizi and murrayi are found at depths 3,000 meters and above, while I. meadi are found from 3,300-5,000 meters.
Stomach dissections of I. meadi indicate the species primarily feed on small crustaceans.
Dissections of Ipnops species’ gonads indicate that these fish are hermaphroditic and lay an average of 900 eggs per clutch.
