Nematodes and four small protostome phyla

Nematoda

A phylum of roundworms that includes free-living, freshwater, marine, terrestrial, and parasitic forms.

Roundworm

A worm with an elongated, cylindrical body covered by a flexible, nonliving cuticle.

Cuticle

A tough, nonliving outer covering of nematodes, composed largely of collagen.
Important: It protects the worm and provides resistance against the environment and, in parasites, the host.

Pseudocoel

A body cavity that is not completely lined by mesoderm.

Hydrostatic skeleton

A fluid-filled body cavity that provides support against which muscles can contract, helping produce movement.

Longitudinal muscles

Muscles running along the length of the body.

Sexual dimorphism

Differences in physical appearance between males and females of the same species.

Dioecious

Having separate male and female individuals.

Monoecious / Hermaphroditic

An individual has both male and female reproductive organs.

animalia

Ascaris Lumbricoides, kingdom;

nematoda

Ascaris Lumbricoides, phylum:

Chromadorea

Ascaris Lumbricoides, class:

Ascaridida

Ascaris Lumbricoides, order:

Ascaris

Ascaris Lumbricoides, genus:

Ascaris Lumbricoides

Ascaris Lumbricoides, species:

Ascaris Lumbricoides

the human intestinal roundworm and an important parasitic nematode

humans

what is the host of Arcaris Lumbricoides

20-40 cm long

female ascaris are approximately how long

female

Has a relatively straight posterior end, male or female Ascaris

ventral side

Ascaris: which side is the vulva on?

vulva

female genital opening

about one-third of the body length from the anterior end

Ascaris: where is the vulva located

Ovary → Oviduct → Uterus → Vagina → Vulva

Female reproductive structures

Ovary

Produces eggs

Oviduct

Eggs pass from the ovary toward the uterus.

Uterus

Where fertilization occurs and eggs receive their shells.

Vagina

Carries eggs toward the outside.

Vulva

Female genital opening.

15-31cm

approximately how long are male ascaris

male

Has a curved posterior end, male or female ascaris

Has two chitinous spicules

how many chitinous spicules does a male ascaris have?

spicules

help hold open the female vulva during copulation.

Testis → Vas deferens → Seminal vesicle → Ejaculatory duct → Cloaca

Male reproductive structures

Testis

Produces sperm.

Vas deferens

Carries sperm away from the testis.

Seminal vesicle

Stores sperm.

Ejaculatory duct

Carries sperm toward the cloaca during reproduction.

Spicules

Chitinous structures used during copulation to help keep the female vulva open and assist sperm transfer.

Cloaca

Common opening for the digestive and reproductive systems in the male.

Mouth → Pharynx → Intestine → Rectum → Anus

ASCARIS DIGESTIVE SYSTEM

Mouth

Located at the anterior end and has three lips:

• One dorsal

• Two ventral

Pharynx

A short, muscular tube that sucks food into the intestine.

Intestine

A long, straight tube where digestion/absorption occurs.

Rectum

Posterior part of the digestive tract.

Anus

Opening through which feces leave the body.

Excretory canals

Located inside the lateral lines, They join just behind the mouth and empty through an excretory pore.

Lateral lines

Longitudinal lines along the body wall containing the excretory canals.

• Nerve ring around the pharynx

• Dorsal nerve

• Ventral nerve

• Longitudinal nerve cords

ASCARIS NERVOUS SYSTEM includes:

longitudinal muscles

what type of musculature does ascaris have

hydrostatic skeleton.

ascaris movement: Because the body contains a fluid-filled pseudocoel, it functions as a _____

pseudocoel fluid.

Oxygen is obtained mainly through processes involving the breakdown of glycogen, with distribution aided by the ___

sexually

Ascaris reproduces ___

uterus

Ascaris: Fertilization occurs in the ____

Ovary → Oviduct → Uterus → Vagina → Vulva → Outside

Egg pathway

Tough cuticle

Ascaris: Protects it from the intestinal environment.

Elongated body

ascaris: Allows it to live within the intestine.

Pseudocoel

ascaris: Functions as a hydrostatic skeleton and helps with movement.

Longitudinal muscles

ascaris: Allow the characteristic side-to-side movement.

Complete digestive tract

Allows food to move continuously from mouth to anus.

Highly developed reproductive system

Allows production of enormous numbers of eggs.

Resistant eggs

Eggs can survive unfavorable conditions and remain infective for long periods.

No specialized respiratory or circulatory organs

Its body plan is sufficient for its parasitic environment.

Human feces → eggs contaminate soil → eggs become infective → humans ingest eggs → infection

ASCARIS LIFE-CYCLE

Turbatrix aceti — Vinegar eel

A free-living nematode commonly found in fermented fruit juices, especially nonpasteurized vinegar.

yeasts and bacteria

Turbatrix aceti — Vinegar eel feeds on:

in liquid environments

where does Turbatrix aceti — Vinegar eel live

by bending its body because it has only longitudinal muscles.

how does turbatrix aceti, vinegar eel move

water and moisture

what does nematodes require for active movement

Herbivorous

• Feed on plants/algae.

Carnivorous

• Feed on other nematodes and small organisms.

Saprophagous

Feed on bacteria and decaying organic material.

Omnivorous

• Eat a mixture of food types.

they help decompose organic matter.

Many nematodes are beneficial because _____

hookworms

live in the intestine of vertebrate hosts, they attach themselves to a mucosa and suck up the blood and tissue fluids from it

mucosa

where do hookworms attach themselves

Necator americanus and Ancylostoma duodenale

the species most important to humans are ___

Necator americanus

american killer

Buccal capsule

Contains cutting structures used to attach to and damage intestinal mucosa.

Ancylostoma caninum

a common hookworm of domestic dogs and cats

20 to 30 c

what do hookworms egg warmth require to develop

24 to 48 hours

how long before hookworms hatch

Trichinella spiralis; trichina worm

A parasitic nematode found in humans, hogs, rats, and other omnivorous/carnivorous mammals.

Encysted juvenile

Juveniles become enclosed in cysts within skeletal muscle.

Humans can become infected by eating infected meat containing larvae.

how can human become infected with thrichinella spiralis

• Anemia

• Protein deficiency

• Malnutrition

• Stunted growth

• Severe health problems

hookworm Heavy infections can cause:

pinworm: Enterobius vermicularis

A common human parasitic nematode. in north america

primarily in the large intestine and cecum.

where does the enterobius vermicularis live

at night around the anal region of their host

enterobius vermicularis: where do they lay their eggs

macracanthorhynchus hirudinaceus

is parasitic in the small intestine of pigs , where it attaches to the intestinal lining and absorb digested food of its host

none

macracanthorhynchus hirudinaceus digestive system:

cylindrical and widest near the anterior end

what shape is the body of the macracanthorhynchus hirudinaceus

Dracunculus medinensis

A parasitic nematode known as the guinea worm.

Dirofilaria immitis

A parasitic nematode that causes heartworm disease in dogs.

Mosquitoes ingest and transmit the microfilariae.

Dirofilaria immitis: how are dogs infected

Acanthocephala

Known as spiny-headed worms.

dioecious.

Reproduction of Macracanthorhynchus hirudinaceus

PHYLUM GASTROTRICHA

phylum of Gastrotrichs

Gastrotrichs

Small organisms found in freshwater and marine environments.

They move using ventral cilia.

locomotion of Gastrotrichs

Cilia

Hair-like structures used for movement.