Generalities of nematodes Flashcards
Nematodes belong to what phylum?
Phylum Aschelminthes/Phylum
Nemathelminthes
In fresh specimens, nematodes are
recovered as __________ in color.
light cream or white
Meaning, a cross section of a roundworm could be divided into two equal parts.
Bilaterally Symmetrical
there are no lines or segments present, unlike earthworms who have segments. (one distinctive way to differentiate)
Non-segmented, Cylindrical in shape
Vital organs of nematodes are enclosed in a _____________
pseudocoel
is the body cavity of the
nematodes.
pseudocoel
is body/protective covering of parasites.
cuticle
Cuticle is composed of _________
substance
chitin/chitin-like
Nematodes have a complete digestive system:
- Mouth
- Buccal cavity
- Esophagus
- Pharynx
- Intestine
- Rectum
- Anus
Some nematodes, depending
on the species, can be equipped with other structures such as _______ and _______ in the buccal cavity
teeth or cutting plates
Part of the dgestive system of a nematodes that is It is muscular and bulb-like.
Esophagus
Has tri-radiate symmetry
Pharynx
Part of nematode for release and excretion of waste
Anus
In terms Reproductive Structures, Nematodes are ______, meaning, they have separate sexes.
Dioecious
Are tubular and coiled
Nematodes
Male or Female Nematode
Smaller in size
Male
Male or Female Nematode
Curved Posterior
Male
Male or Female Nematode
Testes, vas deferens, seminal vesicle, ejaculatory duct ; gubernaculum
Male
Male Nematode
lined with prostate or cement glands
Ejaculatory duct
Male Nematode
accessory copulatory apparatus
gubernaculum
Male Nematode
Used as a copulatory structure
Spicules
Male Nematode
Used to allow the sperm to gain entry into
the vagina of the female worm
Spicules
Male Nematode
Numbers may vary; some have 1, some
have 2
Spicules
Male Nematode
Bell-like structure
Copulatory bursa
Male Nematode
Can be seen in some nematodes such as
hookworms
Copulatory bursa
Male Nematode
assist in
securing the female during copulation;
Dorsal rays
Male Nematode
Dorsal rays are also present
Copulatory bursa
Male or Female Nematode
Bigger in size
Female
Male or Female Nematode
Pointed posterior
Female
Male or Female Nematode
Uterus
Female
Male or Female Nematode
Vagina, ovaries, oviduct are also present
Female
Female Nematodes
This contains eggs
Uterus
What do nematodes don’t have?
Circulatory system
(No blood vessels)
Nematodes are ________: free-living or parasitic
facultative
Reproduction
Produces
Immature/Unembryonated Egg
Oviparous
Produce or lay
mature/embryonated eggs
Ovoviviparous
Produces larvae
instead of Eggs
Larviparous
Example of Oviparous
- Ascaris lumbricoides
- Trichuris trichiura
- Enterobius vermicularis
- Hookworms
Example of Larviparous
Trichinella spiralis
Presence of _______ which act as the nervous system for the parasite
Chemoreceptors
Where can you find the chemoreceptors of nematodes?
- anterior/cephalic portion
- posterior/caudal portion
Chemoreceptors present in the cephalic are called
amphids
Chemoreceptors present in the caudal are called
phasmids
Phasmid worm (which has the phasmid)
belongs to what class?
Class Phasmidia/Secernetia
Aphasmid Worm (which does not have the caudal receptors) belongs to what class?
Class
Aphasmidia/Adenophorea
Stages of Nematodes:
- Adult stage
- Larva (L1 - L4)
- Egg/Ovum
- Microfilaria
The larval stage undergoes four moltings, from _____
L1 → L4
In the laboratory, ___ and ____ are the important
stages
L1&L3
possess uniform muscular
esophagus
L3: Filariform Larva
Non-feeding stage
L3: Filariform Larva
May serve as the infective stage
L3: Filariform Larva
possess expanded and
bulb-like posterior esophagus
L1: Rhabditiform Larva
Feeding stage (open-mouth stage)
L1: Rhabditiform Larva
Egg can be _______ or ______ once release depending on the species
embryonated or unembryonated
are encountered in filarial worms
Microfilaria
It is described as pre-rhabditoid stage
Microfilaria
stage prior
the larval stage
rhabditoid stage
considered as a modified type of egg
Microfilaria
Inside
is an elongated embryo developing.
Microfilaria
