The image shows that both Twi'leks (on the left) and Togruta (on the right) possess lekku.
Lekku, also known individually as a lek, are fleshy, long appendages emerging from the heads of Twi'leks, Togruta, Walunas, and male Ozrelanso; they are also called head-tails or brain-tails. While Twi'leks and Walunas typically have two lekku (though Twi'leks can sometimes have four), Togruta are characterized by having three.
The lekku of Twi'leks are prehensile, tentacle-like structures that develop from the top of their heads. Most Twi'leks have two lekku, however, some, such as Orn Free Taa, have four. These highly sensitive organs can be used to grasp objects. Damage to a lek can be extremely harmful to a Twi'lek, as they are very sensitive to touch; Squoxx died within an hour after one of his lekku was severed. However, the loss of lekku isn't always fatal; Jedi Master Loden Greatstorm survived for a period of time after his lekku were cut off while imprisoned by the Nihil. Had he not perished later in the battle, Greatstorm would have received prosthetic replacements.
Twi'leks can communicate through subtle movements of their lekku, in addition to their spoken language, Ryl. For instance, raising the right lek tip signifies "hello," dipping the left lek tip means "goodbye," crossing both lekku tips twice indicates "love you," and jabbing both lekku tips into the speaker's back translates to "may spice salt your wounds!" Despite their sensitivity, Tw'lek Jedi Matthea Cathley often smoothed her lekku when deep in thought. Her friend Tey Sirrek also claimed her lekku twitched when she lied, a claim she denied. She also had the ability to shake them. Some Twi'leks, like Cham Syndulla, had tattooed lekku. Some Twi'leks wore them hanging down their back or over their chest, while others, such as Bib Fortuna, wrapped them around their necks or shoulders for stylistic reasons.
The term "lekku" also applies to the striped head-tails found on Togruta. However, Togruta possess three such appendages: two lekku positioned at the front, draping over the chest, and a single, thicker lek located at the rear base of their skull. As demonstrated by Governor Gupat Roshti, the lekku of male Togruta are shorter in length compared to those of females. Losing a lek, as seen on the bartender Selda, is not a life-threatening injury, but the appendage will not regenerate. A Togruta's montrals are connected to their lekku. The color of a Togruta's lekku is genetically determined by their DNA.
The lekku of a Togruta grow as they age. In infancy, the lekku are only visible around the head. During adolescence, they extend slightly past the collarbones, but can reach below the waist by the time they reach adulthood. The elder Togruta Gantika had lekku that only reached her stomach.
Ozrelanso males possess lekku in the form of tentacles growing from the sides of their heads.
Lekku were first seen in the film Star Wars: Episode VI Return of the Jedi, along with the Twi'lek species. In The High Republic: Into the Dark, the lekku of Togruta Jedi Master Jora Malli are mistakenly identified as her montrals when they are described as flowing behind her as the airspeeder she is riding goes into a dive. The length of Ahsoka Tano's lekku was reduced between her animated appearance by 4 BBY and her live-action portrayals. For the series Ahsoka, her lekku were slightly lengthened.