Brine Swimmer (CR 3)

Large Vermin
Alignment: Always neutral
Initiative: +3 (Dex); Senses: low-light vision

AC: 17 (-1 size, +3 Dex, +5 natural), touch 12, flat-footed 14
Hit Dice: 5d8+10 (32 hp)
Fort +6, Ref +4, Will +1
Speed: 20 ft., swim 40 ft.
Space: 10 ft./5 ft.
Base Attack +3; Grapple +10
Attack: Bite +5 melee
Full Attack: Bite +5 melee
Damage: Bite 1d6+4
Special Attacks/Actions: Improved grab, rake 1d4+1
Abilities: Str 17, Dex 16, Con 15, Int -, Wis 10, Cha 4
Special Qualities: Immunity to acid and dehydration, snap turn, vermin traits
Feats: -
Skills: Swim +3
Advancement: 6-10 HD (Large); 11-15 HD (Huge)
Climate/Terrain: Warm aquatic
Organization: Solitary or colony (6-30)
Treasure: None

Source: Sandstorm

This large crustacean has dozens of feathery, flat legs and crushing mandibles. It flips through the salt water with great agility.

Brine swimmers are a giant form of brine shrimp, perfectly adapted to the salty, shallow lakes of the waste.

While ordinary brine shrimp feed on algae, these giant creatures eat fish, larval brine swimmers, and even young crocodiles if they can get them. They are a danger to any creature of Medium or smaller size that enters their territory.

A brine swimmer's many legs act as fins, gills, and food-gathering tools. They are fringed with bristles that both filter food from the water and tear at prey held in the creature's mandibles. Brine swimmers swim constantly and seem to cavort as they twist and spin in the water.

Brine swimmer eggs are able to withstand extended periods of drought. If a salt lake dries up, the eggs can survive for several years in a crystalline form, hatching within hours once they are immersed again.

Brine swimmers and their eggs are an important food source for many waste-dwellers, although hunting the creatures is by no means safe.