Lerdethak

The Lerdethak is a creature from the Hork-Bajir homeworld.

Physiology
One of several monsters created by the Arn to act as a natural guardian to keep the Hork-Bajir away from Arn settlements. It resembles a huge gnarled old tree with a drooping blue-rimmed mouth and is surrounded by thousands of vine-like tentacles. The Lerdethak ensnares its prey using its tentacles, and can also store prey in a "pouch" in it's throat.

Source

 * Animorphs #11: The Forgotten.