Dr Hendrik S EGERS Belgian Biodiversity Platform Royal Belgian Institute of Natural Sciences...
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Transcript of Dr Hendrik S EGERS Belgian Biodiversity Platform Royal Belgian Institute of Natural Sciences...
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