member vs chelicera

member and chelicera both are nouns.

Word	Noun	Adjective	Verb	Adverb
member	Yes	No	No	No
chelicera	Yes	No	No	No

As nouns, chelicera is a hyponym of member; that is, chelicera is a word with a more specific, narrower meaning than member:

member: an external body part that projects from the body
chelicera: either of the first pair of fang-like appendages near the mouth of an arachnid; often modified for grasping and piercing

Other hyponyms of member include mouthpart, fang, chela, claw, nipper, pincer, parapodium, fin, pleopod, swimmeret, limb, dactyl, digit.

member (noun)	chelicera (noun)
an external body part that projects from the body	either of the first pair of fang-like appendages near the mouth of an arachnid; often modified for grasping and piercing
the male sex organ
an organization that is a member of another organization (especially a state that belongs to a group of nations)
one of the persons who compose a social group (especially individuals who have joined and participate in a group organization)
anything that belongs to a set or class