Thatcheria mirabilis: Conoidea: Raphitomidae

[JackSullivan]

Looked on as a weird mutant or monstrosity when first discovered in the 19th century, Thatcheria mirabilis (Thatcher's miracle shell iow), this critter's shell caught my eye when I came across at least 3 of them on eBay while hunting for examples of Raphitomidae. Originally very rare apparently due to deep water habit & therefore expensive, increasing stocks have dropped the price to more reasonable levels.

Of the 2 I bought, one is colored a bright yellow while the other shows only faint hints of that color. Both are from the western Pacific in the Japan-Taiwan areas. One is 67mm & the other is 70mm.

As an interesting side note, the bright yellow pigmentation as well as the lesser pigmentation on the other specimens is likely caused by the polymeric pigment pheomelanin, which can exhibit colors ranging from yellow to orange to red. It is produced in the secretory cells at the edge of the shell's mantle from the commonly occurring amino acids phenylalanine > tyrosine > DOPA & cysteine. Tyrosine is also responsible for producing the brown-black pigment eumelanin in the absence of cysteine. Lack of tyrosine or a mutation in the enzyme tyrosinase are the causes of albinism in shells.

Jack