Rotifera

Zoology

1. Stella Maris Polytechnic University Mother Pattern College of Health Sciences UN Drive Monrovia, Liberia Topic: Lophophodata Course: Invertebrate Zoology 201 Submitted to: Mr. Othello Zomonway Submitted by: Group 1(0NE) Date: March 31, 2022

2. LEARNING OBJECTIVES Evolution of Rotifera Overview of Phylum Rotifera General Characteristics Habitat and Habit Morphology Mode of nutrition and movement Reproduction Life cycle of Rotifers Ecological and economic importance

3. Objectives of this work By the end of this presentation, students will be able to: Define and discuss the term rotifera Discuss the types of reproduction in these organisms Classify rotifera Discuss the impacts of these organisms both Economically and ecologically

4. What is rotifera? The term rotifera derives from two Latin words: Rota, meaning wheel and fera, meaning to bear. Rotifera are microscopic aquatic animals of the phylum rotifer.

5. Overview of Rotifers Rotifers are multicellular animals with body cavities lined by mesoderm. These organisms have specialized organs systems and a complete digestive tract that includes both mouth and anus.

6. Evolution of Rotifera Phylogenetic
Natural Selection

7. General Characteristics Rotifers can also be known as Wheel Animalcules. Rotifer’s body can be divided into three: Head, Trunk and food
The body has more than two cell layers, tissues and organs.
All live in aquatic environments. Locomotion: Inch worming (some) Sessile

8. General Characteristics - Habitat Rotifers can be found in still water environments, such as rivers or streams. Eg: Brachionus calyciflorus. They can also be found on mosses and lichens growing on tree trunk and rocks.

9. General Morphology Rotifer’s body divided into three main regions. Head The head carries the corona. Trunk Digestive tract Excretory system Genital organs Foot Petal glands One to four toes

10. Nervous System Bilobed brain dorsal to mastax They have sensory structures 0ne to five photosensitive eyespot maybe on the head

11. Excretory system Flame cells perform excretion A short ciliated intestine extends posteriorly and becomes a cloaca bladder, which receives water from the protonephridia and eggs from the ovaries as well as digestive wastes. The cloaca bladder opens to the outside via an anus.

12. Muscular System Support and Protection The cuticle supports the Rotifera as do the muscles Pseudocoelom also offers support The muscles act as a hydrostatic skeleton The muscles also serve to retract the corona in some species.

13. Systems cont’d

14. Mode of Nutrition Most rotifers are omnivores and some species are carnivorous. Their digestive tract : mouth pharynx, oesophagus , stomach ,intestine , cloaca bladder , and digestive gland. The whirling water movement produced by beating of the cilia helps in feeding of rotifer. Digestion take place in the stomach and absorption in the stomach and intestine. Rotifer diet includes the following :Bacteria ,Algae , protozoans and particles eaten are 10 micrometers or less.

15. Mode of Nutrition cont’d

16. Locomotion Ciliary activity on the corona. Most are motile and quite swimmers and crawlers.

17. Reproduction in Rotifers Rotifers are diocious A female reproductive system includes: Germarium ( egg cells) Vitellarium (yolk cells) Oviduct Uterus Germovitellarium

18. Reproduction cont’d Females reproduce Sexually ( Class Seisonidea) Parthenogenetically ( Class Bdelloidea) Alternation of Both reproductions ( Monogononta) environmental conditions trigger such the alternation Two types of Eggs Amictic or Mictic egg

19. Reproduction cont’d A male reproductive organs include Single teste Ciliated sperms Genital pore Projected penis Note: Offspring are born with adult features

20. Life cycle

21. Classification of Rotifera The phylum Rotifera has been divided into three main classes: Seisonidae e.g. Paraseison annulatus Monogononta e.g. Lecane bulla, Keratella serrulata Bdelloidea e.g. Ptygura pilula, Philodina roseola

22. Classification cont’d

23. Classification cont’d Class Seisonidae (most primitive): Marine Elongated form Corona vestigial Similar in size and form eg: Seison nebaliae

24. Classification cont’d It has a single genus: Seison Epizoic on gills of the crustacean Seisonidae: females produce haploid eggs that must be fertilized and develop into either males or females.

25. Classification cont’d Class Monogononta : Swimming and sessile forms Males reduced in size Eg: Polyarthra

26. Classification cont’d Monogononta: females produce two kinds of eggs; Amictic eggs Mictic eggs

27. Classification cont’d Class Bdelloidea: Swimming or creeping forms Anterior end retractile Corona usually with pair of trochal discs Males unknown

28. Classification cont’d Bdelloidea: females are parthenogenetic (asexual)- produce diploid eggs that hatch into diploid females. Eg: Rotaria Rotaria

29. Rotifer’s Ecology Rotifers are cosmopolitan Most Rotifers can live on the bottom of freshwater lakes or ponds, however a few are marine and some are terrestrial. Most Rotifers eat plankton. Some Rotifers are parasitic. Some Rotifers are epizoic.

30. Economic Importance Rotifers in the wild have little significance to humans. They may have some economic significance, however, because many species are cultured as a food source for aquariums and cultured filter-feeding invertebrates and fish fry.

31. Economic Importance cont’d They also may be used as biological pollution indicators. Eg: Filinia longiseta, heavy pollution

32. Ecological Importance There are three important roles of Rotifers in society: Feed on algae species Serve as important species Indicated water quantity. Eg : Synchaeta grandis, fresh and clean water.