Size ranges of mysis-stage based on measurements of P. japonicus
M1
  1. Body length 2.67 - 3.40 mm
  2. Body shrimp-like in shape
  3. Pereiopods well developed
  4. First and second antennae reduced
  5. Uropods well developed
  6. Primordial pleopod buds present.
M2
  1. Body length 2.99 - 3.90 mm
  2. Unsegmented pleopod buds present
M3
  1. Body length 3.70 - 4.52 mm
  2. Pleopods developed, segmented

(Treece & Yates, 1988)