Marsupial brittlestars: development, provisioning and parental care in the sister group to chordates
Supervisor: Adria LeBoeuf
Project Summary:
Brittlestars are echinoderms, the sister group to chordates, and roughly 5% brood their young inside internal cavities called bursae. In one species, juveniles sit mouth-pressed against the maternal bursal wall, hinting that mothers may nourish their young after birth, an echinoderm analogue of lactation. This project uses the large, abundant, year-round-breeding South African brittlestar Ophioderma wahlbergii to test whether brooding brittlestars provision their young, when in development transfer happens, and how.
The student will establish laboratory husbandry for brooding brittlestars, use labelled tracers to visualise and time maternal-to-offspring material transfer and skeletal mineral deposition, and run cross-fostering experiments to test whether provisioning is tuned to offspring stage. This experimental, developmental approach complements ongoing proteomic and genomic work in the lab and could deliver the first direct evidence of post-emergence maternal provisioning in echinoderms.
Type of Work:
• Develop protocols to collect and maintain brooding Ophioderma wahlbergii and their broods in aquaria, including fieldwork in Cape Town with established South African collaborators, enabling the longitudinal observation.
• Developmental timing with labelled tracers, tracking incorporation into juveniles across early, middle and late stages to time when and where transfer occurs and how the bursal wall changes.
• Cross-fostering: transfer juveniles between mothers, and between developmental stages, to test whether provisioning is stage-matched and mother-specific, distinguishing active provisioning from passive uptake.
• Work with the lab’s proteomic, transcriptomic and genomic pilot datasets to identify and validate transferred substances and their maternal source.
Importance of the area of research concerned:
Parental provisioning after birth has evolved repeatedly across animals, including mammalian milk, caecilian skin-feeding, fish parental mucus and pigeon crop milk, yet it has never been shown in echinoderms despite their being our sister lineage. This project would establish a new invertebrate model for the evolution of parental care, matrotrophy and social transfer of materials. In addition, parental provisioning helps shelter organisms from harsh conditions, so better understanding this phenomenon may help conservation in the face of climate change.
References:
Hakala SM, et al. 2023. Socially transferred materials: why and how to study them. Trends in Ecology & Evolution 38:446–458. DOI: 10.1016/j.tree.2022.11.010 6. Landschoff J, Griffiths CL. 2015. Brooding behaviour in the shallow-water brittle star Ophioderma wahlbergii. Invertebrate Biology 134:168–179. DOI: 10.1111/ivb.12081 7. Landschoff J, Griffiths CL. 2015. Three-dimensional visualisation of brooding behaviour in two distantly related brittle stars from South African waters. African Journal of Marine Science 37:533–541. DOI: 10.2989/1814232X.2015.1095801 8. Matte A, Skerrett-Byrne D, Manica A, LeBoeuf AC. 2025. The origins and molecular evolution of sperm. bioRxiv 2025.11.03.685759. DOI: 10.1101/2025.11.03.685759 9. Reitsema-Wang et al.(2025). ecoevoRxiv https://doi.org/10.32942/X2CD39