#stygofauna

InsertAnInvert 2024 Subterranean week 4: stygofauna

Stygofauna: Return to the Subterranean

The last post I wrote was a piece on Troglobites (which can be found here: http://on.fb.me/1AnfDqN). A Troglobite is an animal that lives in a cave, which is adapted to it's surroundings to the extent they cannot live on the surface. Today I shall discuss the other type of underground fauna, stygofauna. Stygofauna reside in fresh groundwater systems, such as caves in the subterranean environment. There are three types of stygofauna; Stygophiles, Stygoxenes, and Stygobites. Stygophiles inhabit both the surface and subsurface aquatic environments. Stygoxenes are occasionally found in subterranean water but are generally found above the surface. Finally, Stygobites are always found in underground waters.

Stygofauna are named after the River Styx, which in Greek mythology was used by Hades to transport the souls of the dead. This could reflect the fact that subterranean water systems have a lack of food and oxygen, meaning Stygofauna must be adapted to cope with this. They are extremely energy efficient while feeding on plankton, bacteria, or plants with an extremely low metabolic rate. This low metabolism means that some species live longer than terrestrial species as reduced metabolism slows down growth, thus increasing age of maturity e.g. Orconectes australis (a crayfish) from Alabama which can live to 175 years old.

The picture above shows Xibalbanus tulumensis (previously known as Speleonectes tulumensis). X. tulumensis is a pretty terrifying crustacean to come up against, with venom similar to that seen in rattlesnakes which includes a paralysing toxin. That said, panic is not required from humans as the species is only 25-30 millimeters long. Their feeding technique is an adaption due to their blindness (as they do not need sight in dark caves). Claws at the front of the specimen were noted by researchers to resemble hypodermic needles; on further inspection these were found to be linked to venom-filled reservoirs and are used to inject prey.

~SA

Picture: http://bit.ly/1cTpiuh Xibalbanus tulumensis by Joris Van der Ham Further Reading: http://bit.ly/1AqEaLn - A paper entitled ‘Stygobites are more wide-ranging than Troglobites’ by John Lamoreux. http://bit.ly/1PD9XzF - A paper on Xibalbanus tulumensis.[_

How Mexican Blind Cavefish Find Their Way

The limestone caverns of Mexico's Sierra del Abra Tanchipa rainforest contain deep cisterns cloaked in utter blackness. This is where a little fish (Astyanax mexicanus) has evolved to feast or endure famine entombed hundreds of feet below the ground. Mexican cavefish are bizarre, not merely blind but born with eyes that regress until they are completely lost as adults. The bones of their once-round eye orbits have collapsed. In place of eyes, their empty sockets store fat deposits that are covered in the same silvery, nearly translucent scales as the rest of their pale, unpigmented bodies.

"They have been able to invade this really extreme environment... yet they're able to survive and thrive," said Amanda Powers, a UC graduate student and lead author of the study.  

Cavefish start their lives with symmetrical features like other fish. But when they mature, their fragmented skull bones harden in a visibly skewed direction, researchers found. Powers speculates that this adaptation helps the typically left-leaning cavefish navigate by using sensory organs to follow the contours of the cave as they swim in a perpetual counterclockwise pattern. This behavior was observed among captive cavefish, which keep moving around the edges of their tanks while the closely related surface-dwelling fish tend to stay motionless in the shadows of their tank or swim in haphazard ways.

Dr. Joshua Gross, a UC biology professor and co-author, said his biology lab will continue to pursue these and other questions about this fascinating fish that has mastered a dark, subterranean realm, indifferent to the bright, colorful and chaotic world above it.

Stygofauna: Return to the Subterranean

The last post I wrote was a piece on Troglobites (which can be found here: http://on.fb.me/1AnfDqN). A Troglobite is an animal that lives in a cave, which is adapted to it's surroundings to the extent they cannot live on the surface. Today I shall discuss the other type of underground fauna, stygofauna.

Stygofauna reside in fresh groundwater systems, such as caves in the subterranean environment. There are three types of stygofauna; Stygophiles, Stygoxenes, and Stygobites. Stygophiles inhabit both the surface and subsurface aquatic environments. Stygoxenes are occasionally found in subterranean water but are generally found above the surface. Finally, Stygobites are always found in underground waters.

Stygofauna are named after the River Styx, which in Greek mythology was used by Hades to transport the souls of the dead. This could reflect the fact that subterranean water systems have a lack of food and oxygen, meaning Stygofauna must be adapted to cope with this. They are extremely energy efficient while feeding on plankton, bacteria, or plants with an extremely low metabolic rate. This low metabolism means that some species live longer than terrestrial species as reduced metabolism slows down growth, thus increasing age of maturity e.g. Orconectes australis (a crayfish) from Alabama which can live to 175 years old.

The picture above shows Xibalbanus tulumensis (previously known as Speleonectes tulumensis). X. tulumensis is a pretty terrifying crustacean to come up against, with venom similar to that seen in rattlesnakes which includes a paralysing toxin. That said, panic is not required from humans as the species is only 25-30 millimeters long. Their feeding technique is an adaption due to their blindness (as they do not need sight in dark caves). Claws at the front of the specimen were noted by researchers to resemble hypodermic needles; on further inspection these were found to be linked to venom-filled reservoirs and are used to inject prey.

~SA