Characteristics of Botryllus sexiens
| Botryllus sexiens | |
| Colony | |
| Shape | flat |
| Thickness (mm) | 2.5-3.0 |
| Arrangement of zooids | ladder |
| Tunic | transparent, gelatinous, extremely soft |
| Ampullae size (mm: L x W) | 0.7 x 0.2 |
| Formation of colony part including only vascular system | infrequently |
| Color of pigment cells forming pattern on a colony surface | brown |
| Pattern by deposited pigment cells | single pattern |
| Zooid | |
| Length (mm) | 2.5-3.0 |
| Ground color | brown, orange, or yellow |
| Number of tentacles (Large),(Small),(Minute) | L6, S6 |
| Number of stigmatal rows | 9-10 |
| Second row of stigmata | incomplete |
| Number of longitudinal vessels | 3 |
| Number of stomach plication | 11 |
| Pyloric caecum | large |
| Asexual reproduction | |
| Peribranchial budding | all seasons |
| Number of buds in each zooid | R1, L1 |
| Vascular budding | infrequently |
| Cycle of takeover | 5-6 days |
| Sexual reproduction | |
| Breeding season | Jul-Dec |
| Arrangement of gonads (position of ovary) | anterior to the testis |
| Testis shape & color | rosette, grayish |
| Color of eggs | yellow |
| Production of larvae | ovoviviparous |
| Mature egg diameter (µm) | 150 |
| Number of mature eggs | R2, L2 |
| Brooding organ | pouch-like organ formed from branchial sac |
| Embryo size just before hatching (µm) | - |
| Development to larvae | in 4-5 days |
| Release of larvae | shortly before degeneration of parent zooids |
| Larva | |
| Length (mm) | 1.5-1.8 |
| Length of larval trunk (µm) | 440 |
| Number of larval ampullae | 6 |
| Oozooid | |
| Length (µm) | - |
| Number of tentacles | - |
| Number of protostigmata | - |
| Number of stomach plication | - |
| Number of buds | R1 |
| Colony specificity | |
| Present or absent | present |
| Starting stage of allorejection | after vascular fusion |
| Occurrence of subcuticular rejection | no |
| References | Saito et al., 1981a |
| - : not examined |