Cocytan beast

A Cocytan beast was an animal lifeform found Priors 5d, a class P moon of Priors World in Priors system, located in the galaxy's Beta Quadrant. The Cocytan beast appeared scorpion-like. 

Biology and environment
Cocytan beasts shared their body plan with Earth scorpions but their behavior, size and abilities were a closer match with Dewan arthropods. Like them, the beast could bite, and spit venom from its tail.

The beast had four legs and a pair of forelimbs ending in pincers. The carapace consisted of red armor plates with rounded dorns. A pair of horns extended from the forehead. A Cocytan beast had four, bright red eyes.

The Cocytan beast hunted in groups, with members stemming from three different age/size groups: the person-sized Cocytan beast, the larger adult Cocytan beast, and the shuttle-sized elder Cocytan beast. A Cocytan swarm was led by one elder Cocytan beast.

Cocytan beast could survive in cold environments. An elder beast would take refuge in a cave while smaller beasts hunted. Cocytan beasts were drawn to heat sources but avoided nearby fumaroles and its inhabitants, the volatile fumarole worms. 

History
Cocytan beasts hunted survivors from a crash near the elder's cave in June 2256. The Starfleet party defended itself against the beasts while on a the way to another cave for shelter.

On Day 2, Commander Ellen Landry joined a team to recover more shuttle wreckage so engineer Kerwin could fashion a distress beacon. The team was attacked by Cocytan beasts, including the suddenly emerging elder Cocytan beast, but fought them back again.

The team left the area on Day 3, following a battle with Klingons.