Table 1: Characteristics of the ink gland of four species of sea hare.

Sea hare species
A. californica A. juliana A. parvula D. dolabrifera

RER cells
 Abundant rer+++
 Condensed rer+
 Microtubule in vacuoles+
 Number of caveolae(1)0.4 ± 0.2(2)0.2 ± 0.3(2)3.3 ± 0.7(2)2.3 ± 0.4(2)
 Caveolar shapeBalloonBalloonBalloonLong and Branched
 Nucleolus+++
Granulate cells
 Nucleolus++
 Sieve areas++++
 GranulesDiet dependent++
RER and granulate cell
 AbundanceManyManyManyFew
 Spacing in glandCloseCloseCloseDispersed
Vesicle type
 PurplePigmentPigmentPigment
 Amber(4)Protein
 Clear(5)Electron-lucent with sheets
 White(4)ProteinProtein
 Transparent(5)Electron-lucent with tubes
Protein in vesicles
 Lattice dimensions37 ± 6 nm(2)46 ± 10 nm(2)36 ± 11 nm(2)15 ± 2 nm(2,3)

(1) = number/length of cell membranes in µm; (2) = mean ± SD; (3) = in cells beneath epidermis; (4) = amber and white vesicles now termed protein vesicles; (5) = clear vesicles now termed transparent vesicles.