Characteristics of Botryllus horridus
| Botryllus horridus | |
| Colony | |
| Shape | rugged |
| Thickness (mm) | 2.5-3.5 |
| Arrangement of zooids | orval |
| Tunic | a little translucent, gelatinous |
| Ampullae size (mm: L x W) | 0.5-0.8 x 0.2-.025 |
| Formation of colony part including only vascular system | infrequently |
| Color of pigment cells forming pattern on a colony surface | yellow |
| Pattern by deposited pigment cells | single pattern |
| Zooid | |
| Length (mm) | 2.5-3.0 |
| Ground color | dark brown |
| Number of tentacles (Large),(Small),(Minute) | L4, S4, M8 |
| Number of stigmatal rows | R9-11, L8-11 |
| Second row of stigmata | complete |
| Number of longitudinal vessels | 3 |
| Number of stomach plication | 9 |
| Pyloric caecum | large |
| Asexual reproduction | |
| Peribranchial budding | all seasons |
| Number of buds in each zooid | R1-2, L1-2 |
| Vascular budding | infrequently |
| Cycle of takeover | 10 days |
| Sexual reproduction | |
| Breeding season | jul-Sep |
| Arrangement of gonads (position of ovary) | anterior to the testis |
| Testis shape & color | rosette, grayish |
| Color of eggs | yellowish orange |
| Production of larvae | ovoviviparous |
| Mature egg diameter (ƒÊm) | 250-260 |
| Number of mature eggs | R1-2, L1-2 |
| Brooding organ | no brooding organ |
| Embryo size just before hatching (ƒÊm) | 350 |
| Development to larvae | in 8 days |
| Release of larvae | shortly before degeneration of parent zooids |
| Larva | |
| Length (mm) | 1.7-1.8 |
| Length of larval trunk (ƒÊm) | 400-430 |
| Number of larval ampullae | 8 |
| Oozooid | |
| Length (ƒÊm) | 520 |
| Number of tentacles | L4 |
| Number of protostigmata | 5 |
| Number of stomach plication | 4-5 |
| Number of buds | R1 |
| Colony specificity | |
| Present or absent | absent |
| Starting stage of allorejection | - |
| Occurrence of subcuticular rejection | no |
| References | Saito & Okuyama, 2003 |
| - : not examined |