Bee Creek cave harvestman facts for kids
Quick facts for kids Bee Creek cave harvestman |
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|---|---|
| Conservation status | |
| Scientific classification | |
| Genus: |
Texella
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| Species: |
reddelli
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The Texella reddelli, also known as the Bee Creek cave harvestman, is a very rare type of harvestman. It's a special kind of cave-dwelling animal. In 1988, it was added to the United States endangered species list. Six other species from the same karst ecosystem in Travis County and Williamson County, Texas, USA, were also listed at that time.
These tiny creatures live deep underground. They need places with almost 100% humidity and steady temperatures. They hunt and eat small insects called springtails. Because they live only in caves, it's hard for scientists to study them. Their homes are limited, and we don't know much about how they reproduce. This means they are very sensitive to things like habitat destruction. You can find Texella reddelli on both sides of the Colorado River in Texas.
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What is the Bee Creek Cave Harvestman?
These fascinating arachnids are tiny, only about 1/8 of an inch (3.175 mm) long. They have a yellow-brown body and very long legs. Young harvestmen are a yellowish-white color. Since they live underground, they have small eyes and long, thin legs that help them move around in the dark. All seven endangered species, including the Bee Creek cave harvestman, live in the unique Karst ecosystem found in Travis and Williamson counties in Texas.
Where Do They Live?
Bee Creek cave harvestmen make their homes in limestone caves. They can only survive in caves where the temperature stays the same and the air is very humid (nearly 100%). They have been found in caves on both the north and south sides of the Colorado River.
Their habitat is called 'karst' terrain. This type of land forms when calcium carbonate from limestone bedrock slowly dissolves. This happens because slightly acidic groundwater seeps through the rock. This process creates the caves and underground spaces where these harvestmen live. They get their food and energy from nutrients that travel into the caves through groundwater.
What is a Troglobite?
Texella reddelli is a troglobite. This means it's a species that has adapted to live its entire life in a cave. Over a long time, the karst terrain created caves that were not always connected. This led to "islands" of different animal groups that were separated for a very long time. Because they were isolated, these separate groups slowly became different species.
Some species that can move around more have larger living areas and are less isolated. Even though these species are still relatively close to each other, big changes in their environment can make them very vulnerable to extinction. Troglobites need stable temperatures. They often stay in remote corners or on the ceiling of the cave where it's warmest.
Where Are These Harvestmen Found?
Since 1988, when these species were first listed as endangered, scientists have found more caves where they live. They've also discovered new endemic species (species found only in one specific area). It's hard to find these caves, so much of the karst area hasn't been fully explored.
So far, over 700 karst features (like caves and sinkholes) have been found in Travis and Williamson counties. However, only about 100 of these are thought to contain endangered species. While we might find more places where these endangered species live, their total natural range isn't expected to get much bigger.
Similar Species: Texella reyesi
Another species, Texella reyesi, was once thought to be the same as T. reddelli because they look similar. But scientists later realized they are different species. Now, Texella reyesi is also on the endangered species list.
Texella reddelli is known from only three caves in the Jollyville plateau area and four caves in the Rollingwood region. The harvestmen that were first thought to be T. reddelli but are now called Texella reyesi live in Tooth, McDonald, Weldon, and Root caves, also in Texas.
Understanding the Karst Ecosystem
The karst ecosystem in Texas gets its water from rain on the surface and from groundwater. Water flows quickly through cave openings and cracks in the rock. This means the water doesn't get much natural cleaning. This can make the caves vulnerable to pollution from dirty water. This is a big problem in areas where runoff from cities or farms (where chemicals like herbicides and pesticides are used) can get into the water. Pollutants are one of the main dangers to these species, along with urban development.
In a karst ecosystem, the plants and animals living on the surface are very important for photosynthesis. These surface communities provide essential nutrients and energy for the cave ecosystem. Nutrients travel from the surface into the caves as organic debris (like dead leaves). The plant communities around this ecosystem can be anything from grassy pastures to woodlands.
However, plants and animals that are not native to the area (called exotic species) can harm the native species. They compete for food and reduce the overall variety of species. The surface community also acts like a shield. It helps protect the caves from big changes in temperature and moisture. It can also filter out some pollutants before they reach the cave.
What Threats Do They Face?
The areas where these harvestmen live are growing very fast with new buildings and towns. Many caves cannot handle these changes. A lot of caves are already very close to developed areas like roads, schools, houses, golf courses, and shopping centers.
Changes in how water drains, along with more pollution, could cause caves to collapse. It's hard to know how many caves have already been lost, but some have been filled in or collapsed. Experts estimated in 1989 that about 10% of caves in Travis County are destroyed every 10 years. Development activities that change natural water drainage patterns can harm these species. This includes changing the shape of the land, adding or removing ground cover, using irrigation systems, and other activities.
Fire Ants: A Big Problem
Fire ants are especially harmful to the Karst ecosystem. However, the biggest threat to the harvestmen is still the loss of their habitat due to urban development. Fire ants are very aggressive hunters. They have a terrible and long-lasting impact on native ant and other insect communities.
Because the caves where Texella reddelli live are shallow, they are easy for fire ants and other non-native species to invade. Fire ants have been found in over half of the caves known to have endangered species in this ecosystem. Even if fire ants don't always directly eat Texella reddelli, their presence can negatively affect the entire ecosystem and the species that are important in the food chain.
How Can We Help Them Recover?
The future of these special species depends on protecting key areas of the Karst ecosystem. The areas chosen for protection should not be too close together. This helps protect the maximum genetic diversity in case of a disaster. The troglobites need protection from polluted groundwater and from non-native predators like fire ants.
