About Cyrtonaias tampicoensis (I.Lea, 1838)
Cyrtonaias tampicoensis is a bivalve mollusc that can grow over 130 mm (5.1 in) in length, with a general shape similar to the marine bivalves Mercenaria or Spisula. Most individuals have yellowish-brown base coloration marked with faint green rays, and may also display dark brown and black tones; their overall color pattern resembles that of a tropical reef environment. The inner shell of C. tampicoensis holds a light pink to lavender color, which gives the Concho pearl formed in this species the same soft pink and lavender hue. Like other typical bivalve molluscs, C. tampicoensis has a calcareous shell, a muscular foot for movement, and no head. It can either attach to its substrate using byssus threads or move through its habitat, surviving as a filter-feeding mussel. This species lives exclusively in riverine habitats, and it occurs primarily in the Rio Grande basin. Its native range includes the US states of Texas, Colorado, New Mexico, and rare occurrences in Oklahoma via river offshoots, and it is also found in the Coahuila region of Mexico. The muddy, murky, fertile river environment it inhabits is quite different from a marine setting.
