Phylum Nematoda and Nematomorpha

What is Ecdysozoa?

Protostomes that shed their cuticle to grow.

What is the distribution of Phylum Nematoda?

Polar to tropics, marine, freshwater, and terrestrial.

What is the life style of Nematodes?

Parasites of plants and animals, causing billions in losses annually. Some are free-living and feed on bacteria, yeasts, fungal hyphae, algae, or other nematodes.

What is Caenorhabditis elegans?

A model organism for studying development, gene function, and programmed cell death.

What are the distinguishing features of Phylum Nematoda?

Cylindrical shape, cuticle (collagen), lack of cilia and flagella, longitudinal body muscles only, hydrostatic skeleton, and eutely (fixed number of cells).

What are the parts of the alimentary canal in Nematodes?

Mouth, muscular pharynx, non-muscular intestine, pseudocoelom pressure, short rectum, and anus.

How do Nematodes circulate and respire?

They use diffusion, as they lack dedicated organ systems for circulation and respiration.

What is the nervous system of Nematodes?

It consists of a ring of nervous tissue and ganglia around the pharynx, dorsal and ventral nerve cords, and sensory papillae near the head and tail.

How do most Nematodes reproduce?

Most are dioecious, with females being larger than males. Fertilization is internal and development is direct.

What are some representative nematodes?

Ascaris lumbricoides (infects humans), Necator americanus (hookworm), and Parelaphostrongylus tenuis (moose brain worm).

What are the distinguishing features of Phylum Nematomorpha?

Horsehair worms are long, slender, and have a body wall similar to nematodes, with a cuticle, hypodermis, and longitudinal muscles.

What is the digestive system of Phylum Nematomorpha?

The system responsible for breaking down food and absorbing nutrients.

How do larval forms absorb nutrients in Phylum Nematomorpha?

They absorb nutrients from their hosts.

How do adults absorb nutrients in Phylum Nematomorpha?

They absorb nutrients from the water.

What systems are lacking in nematomorphans?

Circulatory, respiratory, and excretory systems.

How does the nervous system in nematomorphans compare to Nematoda?

It is simpler in nematomorphans.

How do adults of nematomorphans reproduce?

They mate in water and shed fertilized eggs into water.

What is Gordius?

A genus of nematomorphans.

Where do juvenile nematomorphans encyst?

On vegetation.

How can nematomorphans infect hosts?

Through drinking or being consumed by arthropods.

How long do nematomorphans spend in the hemocoel?

Several months.

What do nematomorphans do to their hosts?

They drive them to water and emerge.

What is Ascaris lumbricoides?

A parasitic worm that infects humans.

Where is Ascaris lumbricoides commonly found?

In warm and humid regions of the globe.

How many humans may be infected with Ascaris lumbricoides?

Over 1 billion humans may be infected.

What is the length of Ascaris lumbricoides?

It can grow up to 30cm in length.

How many eggs does Ascaris lumbricoides produce per day?

It can produce up to 200,000 eggs per day.

How are the eggs of Ascaris lumbricoides shed?

They are shed with feces.

How long can Ascaris lumbricoides live in the ground?

It can survive in the ground for weeks.

How does Ascaris lumbricoides find a new host?

It finds a new host through the consumption of contaminated food.