1. Marine Biotechnology Lab
Production of Rotifers

2. Rotifers
Rotifers are microscopic aquatic animals of the phylum Rotifera. (40 μm – 2mm).
The name "rotifer" is derived from the Latin word meaning "wheel-bearer"; this makes reference to the crown of cilia around the mouth of the rotifer.

3. Taxonomy PHYLUM: Nemathelminthes or Aschelminthes CLASS: Rotatoria
ORDER: Monogononta
FAMILY: Brachionidae

4. Habitat of Rotifer
Most are originating in fresh water [only two genera and a few species are marine].
Several hundreds of species are sessile
about 100 species are completely planktonic.
Planktonic rotifer
Benthic rotifer

5. Morphology
Most have an elongated body covered with a thin and flexible cuticle, sometimes thickened and more rigid and then termed lorica.
The rotifer’s body is differentiated into three distinct parts:
Head.
Trunk.
Foot.

6. Head
The head carries a corona, a kind of “wheel” of cilia allowing movement of food particles toward the mouth.
Trunk
The trunk contains the digestive tract.
The excretory system.
The genital organ.
Foot
The body ends in a foot (in sessile species) which in turn ending in one or four toes bearing pedal glands that secrete an adhesive substance.
The planktonic species tend to have suspension devices (spines, setae) and reduce or lose their foot.

7. Feeding
Rotifers are filter feeders, accepting small particles up to 30 μm in size including bacteria, algae, yeast and protozoa.
There are basically two main feeding methods for rearing rotifers:
A combination of algae and baker’s yeast.
A totally artificial diet.

8. Application of the rotifers in aquaculture
Several characteristics of rotifers have contributed to their usefulness as good prey for active larvae of marine fish, shrimp and crab, these include:
High nutritional quality.
Small body size: are easily consumed by almost all marine larvae.
Relatively slow motility.
Tolerance to the marine environment.
Easiness to culture it in large scale rapidly and inexpensively.

9. Life history
The life span of rotifers is measured in days and depends on culture temperature.
At 25°C.
It has been estimated to range around 7 days.
Larvae become adults after 0.5 to 1.5 days.
Females start to lay eggs approximately every four hours.
A female will typically produce up to 20 eggs during her lifetime and can carry up to 7 eggs simultaneously.

10. The reproductive activity of Rotifer is influenced by temperature as illustrated in the table below.

11. The reproduction of Rotifer can be either
Sexual (called mictic reproduction).
Asexual (amictic or parthenogenetic reproduction).

13. Disinfection of rotifer culture
The rotifers can be obtained from
The wild.
Research institutes.
Commercial hatcheries.
However, before being used in the production cycle the inoculum should first be disinfected.

14. The most drastic disinfection consists of killing the free-swimming rotifers but not the eggs with a cocktail of antibiotics (e.g. erythromycin, chloramphenicol, sodium oxolinate, penicillin, streptomycin).
The eggs are then separated from the dead bodies on a 50 μm sieve and incubated for hatching and the offspring used for starting the stock cultures.

15. Stock cultures
At the Laboratory the stock cultures for rotifers are kept in sterilized 50 ml conical centrifuge tubes (Fig. 3) at 28°C ± 1°C.

16. Mass culture parameters and conditions to develop rotifer cultures properly.