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
Free-living or sessileEpizoic, parasitic;
limnoterrestrial
•Hue University Rotifer Taxonomy workshop 6-12 March 2010
Phylum RotiferaMorphology: 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 FeaturesMorphology: Corona ciliata; Mastax with trophi; Lorica; (Eutely, syncytia,
unique type of protonephridia)
ReproductionAnhydrobiosis
•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
CoronaHigly 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”
GrindingFor GraspingAs « piston »
•Hue University Rotifer Taxonomy workshop 6-12 March 2010
Lorica: Intracytoplasmatic lamina
… and not being eaten
•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
Rapid population growth
Production of resting eggs
Heterogony
•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
Top Related