Rotifera Flashcards
adult body form
Size: Tiny, typically 50 µm to 2 mm in length.
Characteristics (6)
Microscopic, bilaterally symmetrical pseudocoelomates.
Characterized by a corona, a ciliated structure at the head used for locomotion
and feeding.
Possess a mastax, a specialized jaw apparatus used for grinding food.
Have a pseudocoelom, functioning as a hydrostatic skeleton and aiding in
circulation.
Exhibit eutely, meaning they have a fixed number of cells as adults.
Capable of cryptobiosis—can survive desiccation and extreme conditions by
entering a dormant state.
body wall and support
Body Wall: Covered by a flexible cuticle, sometimes forming a hardened lorica
(shell-like structure).
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Support: Hydrostatic skeleton (pseudocoelom provides structure).
locomotion (2) and body cavity
Locomotion:
- Some swim using cilia on the corona.
- Others crawl using specialized foot structures and adhesive glands.
Body Cavities: Pseudocoelomate (fluid-filled body cavity).
Feeding (3) and circulation
Nutrition (Feeding/Digestion):
-Use ciliary corona to sweep food into the mouth.
-The mastax grinds food before digestion in the gut.
-Diet includes bacteria, protozoa, algae, and organic debris.
Circulation: No dedicated circulatory system; nutrient transport occurs through
fluid movement in the pseudocoelom.
Excretion and respiration
Excretion (Osmoregulation):
Have protonephridia with flame cells for osmoregulation and waste
removal.
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Gas Exchange (Respiration): No specialized respiratory system; gas exchange
occurs via diffusion.
Nervous system (2)
Simple brain with paired longitudinal nerve cords.
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Sensory structures include eye spots, mechanoreceptors, and
chemoreceptors.
Reproduction and development (3)
Some species reproduce sexually, while others use parthenogenesis
(females produce offspring without fertilization).
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In Bdelloid rotifers, males are absent, and reproduction is entirely
asexual.
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Direct development—no larval stage.
Habitat (3)
Found in freshwater, marine, and moist terrestrial environments.
Common in ponds, lakes, rivers, soil, and even mosses.
Can survive extreme conditions by entering a desiccated cryptobiotic state.
Why are bdelloid rotifers unique?
Bdelloid rotifers are famous for their long-term asexual reproduction and ability
to incorporate foreign DNA (horizontal gene transfer).
What role do they have for the environment?
Play a crucial role in aquatic ecosystems by controlling microbial populations
and recycling nutrients.
