The Clawsticker is notable for its two life modes: a passive, photosynthetic summer mode where it is loath to move, and an active, carnivorous winter mode in which it moves almost constantly.
Its highly derived Adoralgae symbiotes in its body (functionally chloroplasts) allow it to photosynthesize. During the extended daylight hours of its polar environment, it photosynthesizes non-stop, often as it basks on submerged rocks. It stores energy as lipids (fats). While initially thin (maximum of 1.25 mm, measured from top to bottom), as it assumes an adult form, it grows fatter and fatter. By the beginning of winter, it can balloon to nearly two-and-a-half times its initial thickness (3 mm). Its "skin" (a simple body surface) contains zeaxanthin as a photo-protective pigment to deal with the continuous high sunlight levels.
In winter, it changes to a pure consumer-form, fueling the transformation with its stored fat. It grows a secondary layer of bait-hairs that don't move, which offer a measure of protection from freezing and desiccation if it gets stranded on land. The bait-hairs at the tips of its arms also gradually fall off, limb by limb, and in their place grow special claw-like bait-hairs. These claws are three times thicker than its normal bait-hairs, and are reinforced with cellulose nanocrystals. Though its claws are softer than the softest kind of wood, they are the second-hardest substance in its whole environment at time of evolution, second only to polar Sea Rupees’ chitin shells. Unable to produce and largely unable to obtain antifreeze compounds, it relies on its fat layers and near-constant movement to prevent freezing. While it has a pale underside in its summer form, by winter, it has a uniformly green coloration. (Its symbiotes are shuffled around during the metamorphosis.)
In its winter form, its eats anything it can identify as food, catch, and rip apart, which is mainly adult Rooted Leafstars. As Clawstickers are brainless, all of their feeding behavior is reflexive, based on random wandering and whether it can "smell" food nearby. The light patches of chemoreceptors at the ends of its arms, while fewer than its ancestor's own, are bigger and more sensitive to smells in its winter mode. Once it smells out food, it makes a beeline straight for it, ripping it apart alive and shoving chunks into the stomach-like organ at the center of its body. Clawstickers will even tear apart living organisms as big as itself, such as Cupotestas, provided they are sick and dying. (e.g., from getting stranded on the beach) While very slow, like starfish, they speed up a little once they initiate feeding, preventing prey from escaping. It lives closer to the shore in winter, allowing it to feed on washed-up organisms and especially Binucleusphotoedo funes strings.
Although its claws are too weak to rip apart Sea Rupee shells under normal circumstances, if Crystalkillers manage to bore a hole into the shell, Clawstickers jab their claws into the hole and scoop out food. It can even dig away at the base of Sea Rupees to eat their roots, although it never does so unless the roots were already exposed. (Its chemoreceptors rarely detect hidden roots.) Immune to Crystalkillers itself, it can pass along Crystalkillers on tiny bits of fungus-like tissue stuck to its body hairs.
Clawstickers are so food-driven in winter that they occasionally cannibalize others of their kind if they are injured. If suddenly poked, it rapidly (by its standards) flips its clawed arms out, whether right side-up or upside-down.
Like its ancestor, when it finds a mate, it reproduces with a plume of gametes released from its underside. (It is only able to reproduce in its summer mode, however.) It also has a brief, Leafstar-like, free-swimming larval stage. Unlike its ancestor, it stops being radially symmetrical as an adult, as two of its arms are longer and thicker than the others. However, its limbs all follow a very similar body plan, and which arm develops into a "front arm" first depends on which direction it prefers to move in as a larva.