Water Ants

Water ants (subfamily aquaformicinae) are, like their name suggests are aquatic ants. These ants are descendants of the red imported fire ant and are found in the marshlands of the southeastern and great plains areas of the US, central America, and parts of South America.

Evolution 

These ants evolved their aquatic traits and behaviors in response to flooding from the holocene extinction.

Biology

Water ants aren't really aquatic, but they walk on water due to their body being covered in small waxy hairs that make it impossible for them to break surface tension or get wet.

They have long spread out legs in order to help them stay afloat. The second pair of legs function are used to slap the water and jump away from any predators. To reduce weight and surface tension, the gaster has grown slimmer but longer. Their stingers still function and they produce a harsher dosage of venom due to the amount of aquatic predators.

Not all water ants are aquatic, it depends on the castes, which are listed below

• Queen ant: looks and acts like a normal fire ant queen, lives in the nest at the center

• Terrestrial worker: normal fire ant worker, only stays in the nest and collects food and materials from the port holes. Repair and reinforce the nest.

• Terrestrial soldier: normal fire ant soldier, lives in the nest and is the last line of defense, has extremely potent venom

• Terrestrial supermajor: normal fire ant supermajor, lifts heavier supplies from the ports, first line of defense

• larvae and eggs

• Queen alate: has wings, long legs and can walk on water, looks like a mix of a water strider, ant, and a crane fly. Becomes a queen ant later in life.

• Male alate: flies, mates, and dies

• Aquatic worker: aquatic varient of the worker caste that collects food and materials for the colony, lives on the water

• Aquatic soldier: aquatic varient of the soldier caste protects the aquatic castes while they forage for food and materials

• Aquatic supermajor: aquatic varient of the supermajor caste that brings in heavier items, also used to push the nest around if the colony needs to move.

Behavior

When the queen first mates, she hides in reeds and hatches the nanitics, these nanitics are aquatic workers and they construct a raft. This small raft turns into a large ice cream cone shaped floating nest (1 ft x 4 ft ) that corrects itself while rocking. These rafts have port holes on the side that are just above the waters surface that are used by aquatic castes to bring food and nest building materials back to the nest.
The ants that come after first few portions of the nest are built can be of any caste. 

Aquatic ants have the ability to jump high in the air, this tactic along with venom is used to escape predators.