Crossword puzzle clue "its code uses just g t a and c"

Its code uses just G, T, A and C

___ code (communication system that uses dots and dashes)

Simple code that uses a half-alphabet shift and that's the key to this puzzle's theme

The shoe department in its flagship store has its own zip code

Violet variety (and the longest common word that uses just the right typing hand)

Knitted garments for women (and the longest common word that uses just the left typing hand)

Seesaw (and the longest common word that uses just the top typewriter row)

This animal presumably spends its entire life in a shell ... correction: just the first part of its life