Colobopsis anderseni facts for kids

Colobopsis anderseni is a special kind of ant. It lives in the mangrove forests of northern Australia. It was once known as Camponotus anderseni.

About Its Name

When this ant was first found in 2001, scientists called it Camponotus anderseni. It was part of a group of ants known as carpenter ants. Later, in 2016, scientists studied these ants more closely. They found that the Colobopsis group was very different. So, they decided to give Colobopsis its own full genus name. This means the ant's new official name became Colobopsis anderseni.

What It Looks Like

Colobopsis anderseni ants are light brown and shiny. Like all arthropods, their bodies have three main parts. The front part is called the prosoma. The middle part is the mesosoma, and the back part is the metasoma. The top side of their middle body part is flat. They also have a clear metanotum at the back of their thorax. These ants do not have stiff hairs under their heads. Their bodies are slightly raised on their lower leg parts. Their eyes are long and point outwards. They are closer to the jaws than to the top of the head. Colobopsis anderseni ants are dimorphic. This means workers come in two different forms or sizes. The larger workers have a face plate that is sunken in and has tiny dots. The front edge is curved. Smaller workers have a wide face plate. Its front edge is also curved and sticks out a bit.

Where It Lives

Colobopsis anderseni has only been found in the mangrove areas of northern Australia. These ants live only inside the twigs of a specific mangrove tree. This tree is called Sonneratia alba. You can find these trees in the Kimberly region. This is in the North Territory of Western Australia. Recent studies show that C. anderseni is the only ant species known to live inside the twigs of these trees. About 81% of ant nests found in the tops of Sonneratia alba trees belonged to C. anderseni. Other ants found in these trees included three types of Tapinoma and two types of Crematogaster. Also found were Monomorium floricola and Tetraponera punctulata.

How It Survives

Living in Flooded Mangroves

Some special ants live in Australian mangroves. They choose this tough home because there are fewer other ants to compete with. Most ants avoid mangroves because the area floods twice a day with the tide. However, mangrove ants have an amazing skill. They can survive these floods that would usually wipe out other ant colonies. All mangrove ants create a sealed air pocket to keep water out of their nests. To avoid drowning, some ants climb to higher parts of the trees. Others hide in air-filled spaces in the trees or in the mud. These hiding spots have limited air. This means the oxygen and carbon dioxide levels can change a lot. This can be a big problem for large ant colonies when oxygen levels get low.

Dealing with Low Oxygen

Scientists from the University of Aarhus in Denmark and Charles Darwin University in Darwin, Australia, studied this problem. They looked at Colobopsis anderseni to see how oxygen and carbon dioxide levels changed in their nests. During a flood, a soldier ant blocks the nest entrance with its head. This stops water from getting inside. When the nest is blocked, it can get very crowded. The ants and scale insects can fill up to half the space. Inside the nest during a flood, there is very little oxygen and a lot of carbon dioxide. Each nest has only one entrance, which is about 1.56 mm wide. The tunnels inside are about 2.31 mm wide. Even when the nest is open, oxygen levels are lower in the parts farthest from the entrance. In a 120 mm long nest, oxygen can drop to 15.7%. During a fake flood, when the nest entrances were blocked, oxygen dropped to less than 0.5% in one hour. After the entrance was opened, oxygen levels slowly went back up. It took almost 20 minutes for a 100 mm long nest to return to normal.

C. anderseni ants face a challenge: how to avoid drowning without running out of oxygen. They are incredibly good at adapting to the harsh mangrove conditions. This allows them to live where other ants cannot. By adapting, mangrove ants have learned to breathe without much oxygen. This is called anaerobic respiration. Scientists saw that oxygen use in the nests stopped, but carbon dioxide production continued. This showed they were breathing anaerobically. A similar study was done on another Australian mangrove ant, Polyrhachis sokolova. These ants can use their front four legs like oars to swim back to their nests before a flood. They then hide in their mud nests, creating an air pocket to block the tide. The study on Polyrhachis sokolova also found similar results. It showed that these ants could also breathe without much oxygen. The studies on C. anderseni and Polyrhachis sokolova are very important for science. They are the only published works that explain how mangrove ants can breathe anaerobically. Before these studies, scientists didn't know how many ant species survived mangrove floods.

Queens and Workers

In another study, scientists watched colonies of Colobopsis anderseni. They recorded how the ants behaved. New queens of C. anderseni were often seen making small holes in the green tips of Sonneratia tree branches. This means that all ant tunnels in Sonneratia branches are started by this ant species. However, the number of these ants in Sonneratia trees can vary a lot, even in nearby areas. This is because Sonneratia trees are often surrounded by seawater. Each tree acts like an island. After queens land and lose their wings, they cannot easily travel to other trees.

One interesting thing scientists noticed is that queens and workers were never found in the same nest. No queens were found in 225 nests that contained C. anderseni workers. In another 400 nests, queens were only found in the soft green shoots at the ends of branches. They were never with workers. In older nests, workers were always present, along with young ants and winged ants. Scientists could not find an egg-laying queen in the main parts of the nests. Many believe that Colobopsis anderseni might reproduce in a special way. This is called thelytokous parthenogenesis. It means queens can lay eggs that hatch into new queens without needing a male. This is very rare in ants. Scientists are now testing this idea using DNA markers.

Ant Colony Behavior

Colobopsis anderseni workers from different nests are very aggressive towards each other. Scientists saw this when watching ants in their natural home and in a lab. When ants from different nests were put together in a Petri dish, they started to fight. This shows that each nest is a separate ant colony.

Colony Size

Because each nest is a separate colony, their colonies are usually very small. This small size helps them adapt to the changing environment. A large colony would need many small nest rooms or a few big ones. If workers had to travel between many small rooms, they would spend more time outside. This would make them easier targets for predators. More importantly, large colonies risk being washed away by tides, waves, or heavy rain. Large nest spaces need very long hollow twigs. These twigs can break easily in strong winds, washing the ants away. Larger spaces in thicker branches would mean the ants have to dig through hard wood. This does not seem to be what these ants do. Another problem is the scale insects, which prefer thin-walled spaces. Finally, a large nest with many entrances and a lot of air is much harder to keep waterproof during a flood.

What It Eats

Colobopsis anderseni ants are rarely seen foraging for food outside their nests. This makes scientists think these ants get their food from another source. Because there are so many scale insects in their nests, their main food is probably honeydew. Honeydew is a sweet liquid produced by scale insects. Scientists don't know much about how scale insects get into new ant nests. It seems unlikely that new queens carry scale insects during their nuptial flights (mating flights). This is because no scale insects are found in nests less than six weeks old.