Many alien looks in Star Trek essentially comprise a forehead make-up or some spots painted into the face. This is the method of choice under technical and budgetary production restraints, because the face is the foremost distinguishing mark among human beings and hence between humans and alien species as well. But there is one other body part that is frequently modified with special alien make-up: the hand. This small article provides an overview of the variations of hands that could be seen in Star Trek.
Aliens with Five Fingers
Most humanoid aliens have five fingers just like humans.
Suckers
Some alien species have vacuum cups on their fingertips.
On their appearances in Enterprise, Tellarites have hands with five fingers, split nails and an additional keratin structure looking like a sixth fingernail on the back of their hand. This specialty was not taken into account for the Tellarites in Lower Decks.
One Bolian in "Star Trek: First Contact" has fingers that look unnaturally long. He may be the only Bolian with this trait. The fingers are never clearly visible in the very movie, the picture is a scan from the Fact Files and probably shows a cut scene or a photo made at the set.
The Tellarite delegate in "Star Trek: The Voyage Home" is the only one of his race seen with five strangely shaped hairy fingers. TOS Tellarites had only three fingers, whereas most later incarnations could be seem with five smooth fingers.
A Zaldan bumps into Wesley and starts to insult the boy without reason, ostentatiously showing his webbed fingers. Wesley recognizes that it is a part of his Academy entrance exam. Knowing that Zaldans hate courtesy, he complains to the man about his bad manners.
Benzites appear in a couple of Lower Decks episodes. We can see the hands in "Second Contact" and in "wej Duj", where they don't have two thumbs, unlike the ones on TNG.
Bolian fingernails are darker in the crescent-shaped area in which human nails are brighter. Note that on the picture the blue make-up on the little finger is already partially gone.
Aliens with Other than Five Fingers
Certainly one way to create a distinct alien look is to give a species more than five fingers or less.
Six fingers
Six fingers per hand seem to be a very rare trait.
The Yridian thumb is grown together with the forefinger. Hence, they are four-fingered, as seen in TNG: "Birthright I" and DS9: "Business as Usual". There are Yridians with five fingers though.
Later Tellarites (TAS, movies, ENT, DIS, PIC, LOW, PRO) have five fingers. The first three-fingered Tellarite since TOS is Jankom Pog, unlike other "modern" members of his race.
The inhabitants of Tarchannen III have three fingers (and three toes). It is a first step in the transformation process to such a creature that the three central fingers of a humanoid grow together.
Vidiian hands are as diverse as the species from which the disease-ridden Vidiians steal them. The hands look just as cluttered as the rest of their bodies.