15th August 14 Brooding behaviour in Ophioderma wahlbergii, a shallow-water brittle star from South Africa Minor DissertationUniversity presented in partial of Cape fulfilment Town of the requirements for the degree of Master of Science in the Department of Biological Sciences University of Cape Town By Jannes Landschoff Supervisor Professor Charles Griffiths The copyright of this thesis vests in the author. No quotation from it or information derived from it is to be published without full acknowledgement of the source. The thesis is to be used for private study or non- commercial research purposes only. Published by the University of Cape Town (UCT) in terms of the non-exclusive license granted to UCT by the author. University of Cape Town Title image: 3D animated brooding Ophioderma wahlbergii from the µCT scan data in Chapter 3, arms cut off. Rendered image is a courtesy of Henry Weber, Volume Graphics GmbH, Heidelberg, Germany. PLAGIARISM DECLARATION I know the meaning of plagiarism and declare that all of the work in the dissertation, save for that which is properly acknowledged, is my own. Date, Signature TABLE OF CONTENTS ABSTRACT .............................................................................................................................................. 3 ACKNOWLEDGEMENTS ........................................................................................................................... 4 CHAPTER 1. REPRODUCTIVE TRAITS IN THE CLASS OPHIUROIDEA: A LITERATURE REVIEW ................ 5 1. Ophiuroid divErsity and distribution ............................................................................................ 5 2. Body structurE ....................................................................................................................................... 5 2.1. General external characters ......................................................................................................................... 5 2.2. Internal anatomy .............................................................................................................................................. 6 3. Biology ..................................................................................................................................................... 7 4. REproductivE biology .......................................................................................................................... 9 4.1. Asexual reproduction ..................................................................................................................................... 9 4.2. Sexual reproduction ........................................................................................................................................ 9 4.2.1. Bursae and sexual organs ...................................................................................................................................... 9 4.2.2. Structure and number of gonads ...................................................................................................................... 10 4.2.3. Colour of gonads ...................................................................................................................................................... 11 4.2.4. Sperms and oocytes ................................................................................................................................................ 11 4.2.5. Reproductive and spawning behaviour ......................................................................................................... 13 4.2.5.1. Pseudocopulation .......................................................................................................................................... 13 4.2.5.2. Spawning ........................................................................................................................................................... 13 4.2.5.3. Behaviour of brooding species ................................................................................................................. 14 4.2.6. Spawning and reproductive cycles .................................................................................................................. 15 4.2.6.1. Seasonality and climate ............................................................................................................................... 15 4.2.6.2. Predictability ................................................................................................................................................... 16 5. DEvElopmEnt ........................................................................................................................................ 17 5.1. Developmental modes ................................................................................................................................ 17 5.1.1. Classification with more than three developmental modes ................................................................. 18 5.1.2. Classification with three developmental modes ........................................................................................ 19 5.1.1.1. Planktotrophic developing larvae .......................................................................................................... 20 5.1.1.2. Larvae with abbreviated development ................................................................................................ 21 5.1.1.3. Larvae with direct development ............................................................................................................. 23 6. Brooding ................................................................................................................................................ 24 6.1. Vivipary vs. brooding ................................................................................................................................... 24 6.2. External brooding .......................................................................................................................................... 24 6.3. Babysitting brittle stars? ............................................................................................................................ 25 6.4. Internal brooding .......................................................................................................................................... 25 6.4.1. Embryonic nutrition .............................................................................................................................................. 26 6.4.2. Size of brooded young ........................................................................................................................................... 27 6.4.3. Brooding cycles ........................................................................................................................................................ 28 6.4.4. Number of brooded young .................................................................................................................................. 28 6.4.5. Duration of brooding ............................................................................................................................................. 29 7. Brooding and Evolutionary aspects ............................................................................................. 29 7.1. Larval mortality and parental care ........................................................................................................ 29 7.2. Adult size and hermaphroditism ............................................................................................................ 30 7.3. Brooding – a reproduction strategy in cold waters? ...................................................................... 31 8. Conclusions .......................................................................................................................................... 31 CHAPTER 2.REPRODUCTION IN THE BROODING BRITTLE STAR OPHIODERMA WAHLBERGII MÜLLER & TROSCHEL, 1842 .................................................................................................................... 33 1. Introduction ......................................................................................................................................... 33 2. MEthods ................................................................................................................................................. 35 2.1. Sampling and study site ............................................................................................................................. 35 2.2. Morphological examinations ................................................................................................................... 35 2.3. Data analysis ................................................................................................................................................... 36 2.3.1. Gonads, sex ratio and egg size ........................................................................................................................... 36 2.3.2. Embryos per female and seasonality .............................................................................................................. 37 2.3.3. Developmental stages of brooded embryos ................................................................................................ 37 2.4. Imaging and photography .........................................................................................................................