From 2speccers2tools wiki

No longer a scavenger, the treel has switched mostly to carnivory. The treel is a specialized hunter of the grappleclong specifically, although it does eat other things occasionally. It has an elongated body of somewhat variable length, and a maximum width of 10 centimeters or so. It is basically just a really weird tree snake.

The treel goes about its life twining around trees, slithering through the branches for its favorite prey. When it sees or hears its prey shuffling about, it quickly strikes with its proboscis, injecting digestive enzymes, some of which are specific enough and work at low enough concentrations to be considered a sort of venom. It then coils around its prey to constrict it to death and continue eating, until it is nothing but a husk. Given that this is the only enjoyment it can get other than sex, the treel has a somewhat pathetic life, although it does not care.

The treel still retains the sandpapery bits of keratin from its digestive patch, although these now extend down its whole body so that it can more easily cling to vertical surfaces via friction. The digestive patch itself is gone, as the treel had little use for it.

Treels are largely solitary, usually aggressive towards each other and even cannibalistic towards smaller treels. They only tolerate each other when mating. When treel eggs hatch, the newborn larvae are simple detritivores that live in freshwater pools and respirate via the skin. They only venture onto land after they grow to about 10 centimeters (from their original size of 4), only then being large enough to kill most “insects”.