The Bythograeidae are a small family of blind
crabs which live around
hydrothermal vents. The family contains 16 species in six genera.[1][2] Their relationships to other crabs are unclear.[3] They are believed to eat
bacteria and other vent organisms. Bythograeidae are a
monophyletic,
sister taxon of the superfamily
Xanthoidea which split to inhabit hydrothermal vents around the
Eocene.[4][5]
Origins
Due to the lack of fossils found in this group the exact date of origin of Bythograeidae remains unknown. It has been suggested that bythograeidae do not originate from an ancient hydrothermal
bathyal groups but instead arose from
brachyuran stock that was adapted to shallow hydrothermal vents and then transitioned to deep sea hydrothermal vents around the Eocene.[6]
The hydrothermal vents where these crabs live are typically short lived, lasting from 10 to 100 years. These are extreme environments, with high temperatures, high concentrations of
sulphides, heavy metals, carbon dioxide and an acidic environment.[8] At this depth there is also limited access to light making photosynthesis nearly impossible. Instead, organisms rely on
Chemosynthetic bacteria to sustain the vast amounts of life in
Chemotrophic ecosystems.[9]
Bythograeidae are
omnivorous scavengers, they are believed to eat
bacteria and other vent organisms however they can also be found far from active sites.
Species
Austinograea rodriguezensisAustinograea alayseae
Genus Allograea Guinot, Hurtado & Vrijenhoek, 2002