Silverswimmers of the Ice Box Age

Four species of Silverswimmers of the middle Ice Box Age. 

Silverswimmers continue headstrong through the Ice Age. The basic ancestral body plan is one that never leaves its larval stage, giving them a very adaptable body plan allowing them to take any form from a simple forum. Well, they may not have the same energetic outgoingness as the Ichthyopterans or the alien majesty of Tera Squids, but these unique neotenic shrimp continue to be a major component of the world's waterways.  

As Terrenumcarids become more terrestrial several other Silverswimmers continue in their ancestral home of freshwater ecosystems. Some of which manage to grow extremely large. 

Sieve Shrimp are massive to 2 meters long only behind the Giant Riverine Silverswimmer in size. Unlike its predatory contemporary, it is much closer in a niche to the Radiodont Aegirocassis as a rather placid filter feeder. All of its legs have been fused by a fold of skin to create a filter-feeding structure. 

Well, it is now unable to walk Sieve Shrimp are the best swimmers among Silverswimmers with a broad flat telson and wide swimming fins. Molting among Sieve Shrimp is quite hard a challenge as getting their exoskeleton off the fused legs is a long process. Sieve Shrimp will stop eating for weeks and the leg basket will fall off to be regrown shortly after molting. Sieve Shrimp larva resemble small Copepods and lack the filter feeding surface of adults instead feeding on small phytoplankton for the first years  of so until the swimming legs broaden out to forum the filter feeding basket.   

 Sieve Shrimp are native to the brackish parts of the coastal lowlands often venturing into the ocean shelf where the upwells bring the most nutrients and filterable food. Well Sieve Shrimp are often found in more open water some of their relatives never leave the safety of the reeds.  

Native to the dense reed patches of the Coastal Lowlands the Reed Hugger is a mantis shrimp-sized, nonswimming Silverswimmer related to, though not descended from the Sieve Shrimp, and shares with its ancestor a diet of small prey species. Well, Sieve Shrimp almost immediately moved back into open habitats, Reed Huggers moved inland as soon as the sea levels dropped losing its ability to swim to jump and flitter between reed stems with hyper-elongated arms to snap up small fish and other Arthropods. 

Reed Huggers like all large Silverswimmers are solitary as adults though Reed Huggers are uniquely elusive as their small size compared to Sieve Shrimp makes them more vulnerable to predatory Fish and Silverswimmers. When alone they move quietly and deliberately and can blend into their environment with their green-tinted shells by standing motionless along reed stems only fleeing inward if pursued by predators.  

Well these two Silverswimmers related but specialized into to different life styles other more primitive Silverswimmers take an interlay different niche as top predators. 

At an impressive seven-and-a-half feet long the largest of all Silverswimmers the Doomcarid is an apex predator of the Coastal Lowlands waterways. Well some of the large Lungefish can contend with them in size and some Scissor Mouths that frequent the water are strong enough to drag them to shore the Doomcarid is often too much effort for either species to handle. 

Feeding on many of the water's larger fish other Silverswimmers and semi-aquatic Tera Squids. A nocturnal hunter the Doomcarid has the most success in the night our dark water striking its prey from behind with a quick burst of speed and sinking its barbed claws into the sides of its prey either pulling smaller prey into its mouth or with larger prey waiting for it to die from shock and bloodloss. 

Doomcarids are a territorial species with social interaction beyond the larval stage only occurring when spawning and will fight each other when they come into contact with one another. 

A relative of the Doomcarid, the Kinglure is also a large predator slightly smaller at 6.5 feet but heavier as it does not swim and lies concealed along the bottom of the water column. Kinglures specialize in smaller prey mostly fish that they can fit into their claws. 

When sustainable prey swims within reach the Kinglure pushes itself off the floor grasping it in its claws and pushing the prey into its sharp second-arm pair to process. Unlike the Doomcarids Kinglures are not territorial as they are constantly moving along the floor and will not fight when confronted by another of their species. 

In conclusion, well they may not be as eye-catching as their Chordate or Mollusk contemporaries the Silverswimmers are still incredibly diverse showing the incredible adaptability of the Arthropods, and don’t show any signs of slowing down as the Ice Age marches on.  

Below a cladogram of Silverswimmer relations.