Phylum Rotifera Microscopic Animals

Phylum Rotifera Rotifera - Latin “to bear a wheel”. Rotifers have an anterior corona. Corona – –a ciliated organ –appears to rotate like a wheel –For locomotion & feeding

Rotifer Characteristics Triploblastic Bilateral Unsegmented Pseudocoelomate Complete digestive tract Anterior corona

Rotifers are usually solitary Swimmers Body is made up of about 1,000 cells

Cont… Posterior end with toes Protonephridia (with flame cells) 0.1mm to 3mm in length Mostly freshwater, some marine About 2,000 species

Rotifer body Head –Corona with cilia –Mouth –Sensory organs –brain Trunk –Largest part, sac-like –Contains organs: mastax, salivary glands, pseudocoelom, protonephridia, stomach, intestine, anus Foot –Locomotion, attachment –Pedal glands, one to two toes

Feeding 1.Cilia on corona beat 2.Water currents bring food 3.Food enters mouth 4.Food enters pharynx 5.Mastax (jaws) grind food 6.Food passes into esophagus 7.Then into stomach 8.Enzymes break down food 9.Nutrients are absorbed

Reproduction Some sexual Several perform parthenogenesis Go to page 168 Read the reproduction section What is parthenogenesis?

Typically, reproduction is thought of as the combination of sperm and egg to form a zygote. In parthenogenesis, however, an egg develops in the absence of fertilization. Adults resulting from parthenogenesis are typically haploid. When forming new cells, the cells of these individuals do not undergo meiosis.zygote meiosis. "Parthenogenesis" is derived from parenthenos, Greek for "virgin birth". When parthenogenesis occurs in nature, an offspring is produced in the absence of a genetic father. Fertilization is able to occur in a female only setting.nature Artificially induced parthenogenesis typically results in an egg that has the capacity to divide cellularly. Forcing parthenogenesis in a non parthenogenetic individual is not done with the purpose of creating a viable offspring. Instead, experiments have been conducted to test conditions suitable for inducing divisionArtificially induced parthenogenesis