Blind cave eel facts for kids
Quick facts for kids Blind cave eel |
|
|---|---|
 |
|
| Conservation status | |
| Scientific classification | |
| Genus: |
Ophisternon
|
| Species: |
candidum
|
| Synonyms | |
|
Anommatophasma candidum Mees, 1962 |
|
The blind cave eel (Ophisternon candidum) is a special type of cavefish that belongs to the Synbranchidae family. It's the longest cavefish in Australia, growing up to 40 centimeters (about 16 inches) long. It's also one of only three animals with backbones in Australia that live only in underground water. The others are the blind gudgeon and the Barrow cave gudgeon.
This eel is blind, has a long, eel-like body, and its skin has no color, appearing white or pink.
The blind cave eel lives only in northwestern Australia. You can find it in the Cape Range, Pilbara, and Barrow Island areas. It's hard to spot because it lives underground. Between 1959 and 2017, it was seen only 36 times. Interestingly, blind cave eels in the Pilbara region are genetically different from others, showing they have been separate for a long time.
Blind cave eels live in completely dark underground waters that are cut off from the ocean. They usually live in caves and dig into the sediment at the bottom. They eat crustaceans, other small creatures from the cave floor, and sometimes even land animals that get washed into the cave system. We don't know much about their behavior, but male blind cave eels are known to build and guard their homes.
The blind cave eel is used for research and sometimes kept in aquariums. It's not dangerous to humans. This species is listed as vulnerable under the Environment Protection and Biodiversity Conservation Act 1999. It's also listed as endangered by the IUCN Red List. In 2008, the Australian Minister signed a plan to help protect them from human activities and environmental changes. A challenge in protecting them is how hard they are to find. However, a new method using environmental DNA (eDNA) since 2020 makes it easier to find them and help with their conservation.
Contents
What's in a Name?
In 1962, this species was first described as Anommatophasma candidum. The word "Anommatophasma" was a new genus name. Later, in 1976, scientists changed its name to "Ophisternon candidum".
The scientific name Ophisternon candidum has an interesting meaning. "Ophis" comes from a Greek word meaning "serpent" (like a snake). "Sternon" is a Greek word for "chest." "Candidus" is a Latin word meaning "white," which refers to the eel's skin color.
In Australia and the United Kingdom, this fish is called the blind cave eel. In the United States, it's known as the blind freshwater eel. Both names describe its eel-like body, its home in caves, and the fact that it has no visible eyes.
How to Describe a Blind Cave Eel
The blind cave eel is Australia’s longest cavefish. It can grow up to 400 millimeters (about 16 inches) long. However, adult eels are usually around 340 millimeters (about 13 inches) long. Their size can range from 60 to 385 millimeters (about 2 to 15 inches).
Its body is round, long, and looks like an eel. Its head is quite short, and it doesn't have any visible eyes. It has many small, slimy pores on its head. The eel has a large mouth with thick lips inside. It also has several rows of strong teeth and a well-developed tongue. It has two pairs of nostrils. The smaller pair is on top of its upper lip, and the larger pair is between its snout and forehead. There are several skin folds around its throat.
The blind cave eel has four pairs of well-developed gills that are shaped like a crescent moon. The gill openings are wide and horizontal. It doesn't have scales or fins, except for a thin, rayless membrane around its tail. It has a clear lateral-line system, which helps it sense movement in the water, running from its head almost to the tip of its tail. Its anus is located in the front half of its body. This eel also has between 151 and 169 vertebrae (backbones).
The blind cave eel's colors can vary from having no color at all to being white or pink.
Where They Live and Their Genes
The blind cave eel has been seen only 36 times in 20 different places between 1959 and 2017. These sightings were in three main regions: Cape Range, Pilbara, and Barrow Island. This means the blind cave eel lives only in north-western Australia.
The Cape Range region has 14 recorded sites, making it the most common place to find a blind cave eel. Some of these sites include Tantabiddi Well, Milyering Well, and Kubura Well cave.
In the Pilbara Region, there are three known sites. In the Barrow Island Region, there are also three known sites.
The Pilbara and Barrow Island regions were only discovered in 2009. Before that, from 1959 to 2009, people thought blind cave eels only lived within 100 kilometers (about 62 miles) of the Cape Range underground area. When a specimen was found in the Pilbara region in 2009, it showed that their known living area extended to 200 kilometers (about 124 miles). Interestingly, the blind cave eels found near Bungaroo in Pilbara are genetically different from those in other places. This is probably because they have been separated for a long time, leading to their own unique family line.
Their Home: Underground Waters
Blind cave eels prefer to live in underground waters and caves. These waters often have very high salt levels and are clearly separated from fresh water on the surface. The underground waters have a pH value of 7–8, a salt level of 1–8%, and are quite hard. Even though ocean tides can affect these waters, they don't connect much with surface fresh water. The blind cave eel lives only in these underground waters, a habitat shared by only one other animal with a backbone in Australia, the Blind gudgeon. The underground waters where the blind cave eel lives are completely dark, showing how well they have adapted to living without light.
Blind cave eels like to live in old wells, dark caverns, cracks in rocks, under coastal limestone, or by digging into soft sediments. Because of where they live, it's very hard for people to reach these underground waters. Their living spots are usually very small. Most sightings are just observations rather than collecting the eels, because it's hard to trap or net them. Also, most sightings don't include the deeper parts of the anchialine system, and usually no more than three blind cave eels are seen at one time.
What They Eat
The blind cave eel mainly eats crustaceans and other small creatures found on the cave floor. However, they have also been seen eating land animals that get washed into the cave system. Scientists who looked at the contents of their guts found creatures like Halosbaena tulki, Stygiocaris, Philosciidae, and larvae. Even though they live in dark underground waters, they are sometimes seen in shallow water, resting on rocks by themselves or in pairs.
Reproduction and Life Cycle
We don't know much about the blind cave eel's life cycle because it's so hard to find and study them. When it comes to mating, the male blind cave eel usually takes on the job of building a nest or burrow and guarding it.
Why They Matter to Us
The blind cave eel is not a threat to humans. We don't eat them, and fishing industries aren't interested in them. Blind cave eels are mainly used for research, and they are rarely kept in aquariums. There was one time in 2015 when two blind cave eels were collected from Barrow Island. These two eels stayed alive in an aquarium for several days.
Protecting the Blind Cave Eel
Conservation Status
The Environment Protection and Biodiversity Conservation Act 1999 says the blind cave eel is vulnerable. The Endangered Species Protection Act 1992 also lists it as vulnerable. In Western Australia, the Wildlife Conservation Act 1950 and the Wildlife Conservation Notice 2006(2) say the blind cave eel is rare. The International Union for Conservation of Nature (IUCN) Red List of Threatened Species lists the blind cave eel as endangered.
How Human Activities Affect Them
The approved plan to protect the blind cave eel points out several threats from human activities. These include mining, city development, construction, and dumping waste. These activities can lead to pollution and too much sediment in the water. Also, wild fish, especially guppyes, might invade the blind cave eel's territory in open areas.
In the Cape Range region, the Ningaloo Coast World Heritage Area protects the west and north coasts. However, in other parts, some places where eels were found have been harmed by marina developments and taking too much water. On Barrow Island, which is a protected nature reserve, gas field mining happens near where blind cave eels have been found. This could potentially threaten them. The Pilbara region is heavily affected by a lot of water being taken out and by mining. None of these areas are protected, which makes conservation urgent. Since the eels in Pilbara are genetically different, it's very important to manage and protect them to reduce human activities there.
Approved Conservation Advice
On March 26, 2008, the Australian Minister approved a plan to help protect the blind cave eel. This plan gives priorities for researchers and local communities to learn more about the eel and help it recover.
What Researchers Need to Do
The plan suggests that researchers should explore more about the blind cave eel’s genetic differences. It also suggests studying how many eels there are, what they need to survive, and how different threats affect them.
What Local Communities Can Do
The conservation plan suggests three main ways to help the blind cave eel recover.
First, it's important to protect the blind cave eel's home and reduce disturbances around it. This means setting up formal agreements to limit human activities and land use near the Cape Range, Pilbara, and Barrow Island regions. It also stresses the importance of protecting the underground water system and keeping pollutants like chemicals, waste, and sewage out of it. The plan also suggests continuously checking on the three known regions and updating management actions to see how well they are recovering. This includes watching for sudden changes in water flow or levels, which could lead to more pollution.
Second, it's important to find out what other animals might compete with or prey on the blind cave eel in the underground water system. This includes diseases, parasites, and other fish species that threaten the eel. Actions should be taken to keep these threats away.
Third, it's important to share information about conservation and teach local communities to raise awareness about the blind cave eel. The plan notes that because the blind cave eel lives in underground waters, most people won't see its habitat. This makes it harder for them to understand why it needs protection.
Finding Eels with Environmental DNA
In 2020, a new method using environmental DNA (eDNA) was introduced. This method allows scientists to test water samples for the eel's DNA, making it easier to find and monitor this rare species. This new detection method replaced older, less effective ways of sampling. It helps overcome the challenge of the blind cave eel being so rare and hard to find. This method also helps accurately detect invasive species, allowing quick actions to reduce threats in the region.
Images for kids
