Phylum Rotifera

1. PHYLUM ROTIFERAPHYLUM ROTIFERA
Philodina

2. PHYLUM ROTIFERAPHYLUM ROTIFERA
Rotifera- Latin word meaning “wheel-Rotifera- Latin word meaning “wheel-
bearer” (bearer” (rotarota=wheel + =wheel + ferofero=to bear).=to bear).
composed of several composed of several ciliatedciliated tufts around the tufts around the
mouth that in motion resemble a wheel mouth that in motion resemble a wheel
Structure of Philodina; a live Philodina

3. 2000 species throughout the world.2000 species throughout the world.
- freshwater inhabitants- freshwater inhabitants
- marine- marine
- terrestrial- terrestrial
- epizoic or parasitic- epizoic or parasitic
- benthic – swim or creep on vegetation- benthic – swim or creep on vegetation
Range in size – 40Range in size – 40µµm- 3mm in length.m- 3mm in length.
- most are between 100-500- most are between 100-500µm long.µm long.
Some have beautiful colors, most are Some have beautiful colors, most are
transparent.transparent.
PHYLUM ROTIFERAPHYLUM ROTIFERA

4. The morphology is very diverse, but their The morphology is very diverse, but their
body is cylindrical or spherical.body is cylindrical or spherical.
Floaters - globular & saclikeFloaters - globular & saclike
Creepers & swimmers – elongated and Creepers & swimmers – elongated and
wormlikewormlike
Sessile - vaselike Sessile - vaselike
PHYLUM ROTIFERAPHYLUM ROTIFERA

5. PHYLUM ROTIFERAPHYLUM ROTIFERA
Variety of form in rotifers

6. PHYLUM ROTIFERAPHYLUM ROTIFERA
Morphology of rotifers:Morphology of rotifers:
HeadHead: bears a ciliated crown or corona: bears a ciliated crown or corona,,
 locomotion and feedinglocomotion and feeding..
The cilia create currents of water toward the mouth- draw in small planktonic food.The cilia create currents of water toward the mouth- draw in small planktonic food.
TrunkTrunk: contains visceral organs.: contains visceral organs.
FootFoot: segmented (when present).: segmented (when present).
Ringed with joints that can telescope to shorten (in some sp.).Ringed with joints that can telescope to shorten (in some sp.).
The 1-4 toes secrete a sticky substance from the The 1-4 toes secrete a sticky substance from the pedal glandspedal glands for for
attachment.attachment.
Used by both sessile and creeping forms.Used by both sessile and creeping forms.

8. Digestive system- completeDigestive system- complete
Omnivorous: feed by sweeping minute organic Omnivorous: feed by sweeping minute organic
particles / algae forward the mouth by the particles / algae forward the mouth by the
beating of the coronal cilia.beating of the coronal cilia.
Carnivorous (some sp.)- feed on protozoa & Carnivorous (some sp.)- feed on protozoa &
small metazoans- capture by trapping or small metazoans- capture by trapping or
grasping.grasping.
TrappersTrappers- funnel-shape area around the mouth to - funnel-shape area around the mouth to
capture prey.capture prey.
HuntersHunters- trophi that can be projected & used like - trophi that can be projected & used like
forceps to seize prey.forceps to seize prey.
PHYLUM ROTIFERAPHYLUM ROTIFERA

9. Pharynx (Pharynx (mastaxmastax) fitted with a muscular ) fitted with a muscular
portion that is equipped with hard jaws portion that is equipped with hard jaws
((trophitrophi)- sucking & grinding up food )- sucking & grinding up food
particles.particles.
Absorption occurs in the stomach.Absorption occurs in the stomach.
PHYLUM ROTIFERAPHYLUM ROTIFERA

12. Reproduction:Reproduction:
Female rotifers (have 1 or 2 syncytial Female rotifers (have 1 or 2 syncytial
ovaries ovaries (germovitellaria)(germovitellaria)..
Produce yolk as well as oocytes.Produce yolk as well as oocytes.
Rotifers are dioecous, but males are Rotifers are dioecous, but males are
unknown in many species.unknown in many species.
(Dioecous- having male & female organs in separate (Dioecous- having male & female organs in separate
individuals).individuals).
PHYLUM ROTIFERAPHYLUM ROTIFERA

13. Divided into 3 classes:Divided into 3 classes:
PHYLUM ROTIFERAPHYLUM ROTIFERA
class
order

14. Class Seisonidea Class Seisonidea (most primitive)(most primitive)::
MarineMarine
Elongate formElongate form
Corona vestigialCorona vestigial
♀♀ & ♂& ♂ similar in size and form similar in size and form
Single genus: Single genus: SeisonSeison
Epizoic on gills of a crustaceanEpizoic on gills of a crustacean
SeisonideaSeisonidea: females produce haploid eggs : females produce haploid eggs
that must be fertilized and develop into either that must be fertilized and develop into either
males or females.males or females.
PHYLUM ROTIFERAPHYLUM ROTIFERA
Crustacea:
Nebalia
Seison annulatus

15. Class Bdelloidea:Class Bdelloidea:
Swimming or creeping formsSwimming or creeping forms
Anterior end rectractileAnterior end rectractile
Corona usually with pair of trochal discsCorona usually with pair of trochal discs
Males unknownMales unknown
2 germovitellaria2 germovitellaria
PHYLUM ROTIFERAPHYLUM ROTIFERA

16. BdelloideaBdelloidea: females are parthenogenetic : females are parthenogenetic
(asexual)- produce diploid eggs that hatch (asexual)- produce diploid eggs that hatch
into diploid females.into diploid females.
Examples: Examples: PhilodinaPhilodina & & RotariaRotaria
PHYLUM ROTIFERAPHYLUM ROTIFERA
Philodina
Rotaria

17. Class Monogononta: Class Monogononta:
Swimming or sessile formsSwimming or sessile forms
Single germovitellariumSingle germovitellarium
Males reduced in sizeMales reduced in size
Examples: Examples: AsplanchnaAsplanchna & & EpiphanesEpiphanes
PHYLUM ROTIFERAPHYLUM ROTIFERA
Asplanchna Epiphanes

18. PHYLUM ROTIFERAPHYLUM ROTIFERA
MonogonontaMonogononta: females produce two kinds : females produce two kinds
of eggs;of eggs;
AmicticAmictic eggs- diploid eggs that have not eggs- diploid eggs that have not
undergone reduction division, cannot be undergone reduction division, cannot be
fertilized & develop only into females. fertilized & develop only into females.
MicticMictic eggs- undergone meiosis and are eggs- undergone meiosis and are
haploid- if:haploid- if:
Unfertilized- develop quickly into males.Unfertilized- develop quickly into males.
Fertilized- they secrete a thick shell and become Fertilized- they secrete a thick shell and become
dormant for several months before developing into dormant for several months before developing into
females. females.

19. The importance of rotifers in the The importance of rotifers in the
ecosystems???ecosystems???
PHYLUM ROTIFERAPHYLUM ROTIFERA