AN INTRODUCTION TO THE ROTIFERA Dr Hendrik SEGERS

AN INTRODUCTION TO THE ROTIFERA Dr Hendrik SEGERS Belgian Biodiversity Platform Royal Belgian Institute of Natural Sciences Brussels, Belgium

The Rotifera What are Rotifera? Eating… …. and not be eaten Survival through time and space: Reproduction and dispersal Problems and opportunities Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Phylum Rotifera Ca. 2030 species: 3 Seisonida, 461 Bdelloidea, 1566 Monogononta Small (40 -3500µm) worms Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Phylum Rotifera Predominantly freshwater, some marine, brackish water; Highly abundant: 103. L-1 to 105. L-1: soda waters; One of the main zooplankton groups Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Phylum Rotifera Uses: Aquaculture: Brachionis plicatilis group for fish larvae; Ecotoxicological assays (B. calyciflorus) Scientific test organisms (e. g. , parthenogenetic reproduction) Ecological and environmental studies (e. g. , water quality assessment) … Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Phylum Rotifera Pelagic, littoral, interstitial; Solitary or colonial üFree-living or sessile üEpizoic, parasitic; ülimnoterrestrial Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Phylum Rotifera Morphology: Body: head, trunk, foot Head: corona Body: lorica + pseudocoelom, incl. digestive, excretory, reproductive system Foot (no tail) with attachment glands Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Unique Features Morphology: Corona ciliata; Mastax with trophi; Lorica; (Eutely, syncytia, unique type of protonephridia) Reproduction Anhydrobiosis Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Eating… Creation of water current by corona ciliata: Locomotion: swimming Feeding: filtering Food particle processing by mastax with trophi Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Corona Higly adaptible! Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Mastax with trophi Differentiation of the pharynx Mastax = Muscular organ containing Hard elements = trophi Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Trophi Higly adaptible! Different “types” For As Grinding Grasping « piston » Hue University Rotifer Taxonomy workshop 6 -12 March 2010

… and not being eaten Lorica: Intracytoplasmatic lamina Hue University Rotifer Taxonomy workshop 6 -12 March 2010

… and not being eaten Protection by lorica Function: Stiffness Buoyancy Protection: �passive �Active Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Lorica Phenotypic plasticity: morphological adaptation to environment • Simple: cyclomorphosis • Complex: predator-induced Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Cuticle Gelatinous glycocalyx Secreted by tegumental glands (trunk, foot) Function: Protection: �Chemical (unpalatability) �Mechanical Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Reproduction Seisonida: bisexual, sexual repoduction Bdelloidea: exclusive asexual parthenogenesis Monogononta: heterogony Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Reproduction Heterogony Rapid population growth Production of resting eggs Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Resting "eggs" Encapsulated embryos; Draught-resistent, hatching at specific clues; Survival through time and space; Highly effective dispersal stages Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Bdelloids: anhydrobiosis Survival through metabolic inactivity; Draught-resistent, reversal at specific clue; Survival through time and space; Highly effective dispersal stages Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Constraints for studying Rotifera… Size… Taxonomic impedement Cryptic speciation e. g. , Brachionus plicatilis complex Sampling and sample handling Hue University Rotifer Taxonomy workshop 6 -12 March 2010

… and opportunities: The Bdelloidea of Thailand Ecology and diversity of sessile rotifers Molecular and morphological approach combined: Cryptic diversity of Rotifera Phylogeny Genetics of bdelloids Hue University Rotifer Taxonomy workshop 6 -12 March 2010

Thank you for your attention Hue University Rotifer Taxonomy workshop 6 -12 March 2010