For many benthic marine invertebrates, inversion (being turned upside-down) is a common event that can increase vulnerability to predation, desiccation and unwanted spatial transport, and requires behavioural ‘self-righting’ to correct. While self-righting behaviour has been studied for more than a century, the repeatability (R) – the portion of behavioural variance due to inter-individual differences – of this trait is not well understood. Heritability and the evolution of animal behaviour rely on behavioural repeatability. Here, we examined the self-righting technique of a cold-water holothurid, Parastichopus tremulus, and assessed the repeatability of this behaviour. Under laboratory conditions, P. tremulus consistently used muscle contractions to curl its body and roll itself back to an upright position, which provided for rapid (x̅ ± SD = 96.7 ± 49.8 s) and highly repeatable (R = 0.75) self-righting in the short term that varied between individuals (range of individual average righting times = 34.8–217.0 s). Righting time tended to increase with animal size; however, substantial variation was evident at comparable sizes, as average righting time ranged from 34.8–155.5 s for animals ~20 cm in body length. Contrary to previous studies on other echinoderms, we found no evidence of improved righting times for P. tremulus over time. This study ultimately provides the first detailed documentation of self-righting behaviour for P. tremulus and suggests that this species displays a high degree of repeatability for this trait in the short term.

The sea cucumber Holothuria (Theelothuria) notabilis for the first time is reported from the Beibu Gulf, South China Sea. A morphological description of this new record with colour figures and scanning electron microcopy images of its ossicles are provided. This finding widens the geographical range of H. (T.) notabilis and indicates that this species may expand northwards in the South China Sea. With our new record, the subgenus theelothuria is now represented by three species in China.

Holothuria (Holothuria) dakarensis (Holothuroidea: Holothuriidae) is recorded for the first time in the south-western Atlantic, from mangroves in Macau, Rio Grande do Norte State, and deposited in the Coleção de Invertebrados Paulo Young, Universidade Federal da Paraíba, Brazil.

Thyone pawsoni and Holothuria (Theelothuria) princeps are reported from shallow water of the South Atlantic Ocean. A morphological description of these new records with colour figures and scanning electron microscopy images of their ossicles are provided. With these two new records for the Brazilian Coast, the genus Thyone is now represented by two species and Holothuria by six.