Phylum Nematoda Flashcards

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Questions and Answers

Which of the following are characteristics of nematodes?

Elastic cuticle that molts (correct)

Segmented

Triploblastic, bilateral (correct)

Pseudocoelomate (correct)

Are nematode roundworms segmented or unsegmented?

Unsegmented

What do nematodes eat?

Everything

What are the two classes of nematodes?

Secernentea (Phasmidea) and Adenophorea (Aphasmidia) Signup and view all the answers

Is the nematode digestive tract complete or incomplete?

Complete Signup and view all the answers

What two characteristics are unique in nematodes?

Excretory system and only longitudinal muscles Signup and view all the answers

What is the nematode cuticle made of?

Collagen Signup and view all the answers

Describe the nematode digestive system.

Mouth (teeth; jaws; stylets; lips) → buccal cavity → muscular pharynx → long tubular intestine (digestion and absorption) → short rectum → anus Signup and view all the answers

What helps push food along in the nematode?

Hydrostatic pressure in pseudocoelom and muscular pharynx Signup and view all the answers

Describe the nematode nervous system.

Anterior nerve ring + anterior and posterior nerves + connecting commissures Signup and view all the answers

What do nematodes excrete in terms of nitrogenous waste?

Ammonia and urea Signup and view all the answers

What are the osmoregulation and excretion systems of a nematode?

Glandular system and tubular system Signup and view all the answers

Describe the glandular system in aquatic nematodes.

Renettes absorb wastes from pseudocoelom and empty them to outside through an excretory pore Signup and view all the answers

Describe the tubular system in parasitic nematodes.

Renettes unite to form a large canal, which opens to the outside through an excretory pore. Signup and view all the answers

Are nematodes dioecious or monoecious?

Most dioecious Signup and view all the answers

Where do nematodes have their gonads?

Free in pseudocoelom Signup and view all the answers

What is the bursa in a nematode?

Posterior flap of tissue that aids in sperm transfer during copulation Signup and view all the answers

What kind of fertilization occurs in nematodes?

Internal fertilization Signup and view all the answers

What is ovoviviparity and what phylum may exhibit this?

Eggs develop within the female reproductive tract and are nourished by food stored in the egg; larval birth; nematoda Signup and view all the answers

Do nematodes have a larva?

Yes Signup and view all the answers

How many times does a nematode larva molt?

4 Signup and view all the answers

What evolutionary adaptations do parasitic nematodes possess?

High reproductive potential, life cycles that increase the likelihood of transmission between hosts, enzyme-resistant cuticle, resistant eggs, encysted larvae Signup and view all the answers

What are five important nematode parasites of humans?

Ascaris lumbricoides, Enterobius vermicularis, Necator americanus, Trichinella spiralis, Wuchereria spp. Signup and view all the answers

What does Wuchereria spp (Filarial worms) cause in humans?

Elephantitis Signup and view all the answers

What super group do nematodes belong to?

Ecdysozoa Signup and view all the answers

Study Notes

Nematode Characteristics

Triploblastic, bilateral, and unsegmented.
Pseudocoelomate structure with a round cross-section.
Elastic cuticle made of collagen that undergoes molting.
Complete digestive tract comprised of mouth, buccal cavity, pharynx, intestine, rectum, and anus.
Unique excretory system featuring 1-2 renette cells or collecting tubules.
Presence of only longitudinal muscles.

Nematode Classification

Classified into two main classes:
- Secernentea (Phasmidea)
- Adenophorea (Aphasmidia)

Feeding Habits

Nematodes are omnivorous, feeding on a wide range of organic materials.

Digestive and Excretory Systems

Digestive system utilizes hydrostatic pressure from pseudocoelom and a muscular pharynx to propel food.
Nematodes excrete nitrogenous waste as ammonia and urea.
Osmoregulation and excretion managed through a glandular system and tubular system.

Glandular and Tubular Systems

Aquatic nematodes possess a glandular system with renettes that absorb waste and release it externally.
Parasitic nematodes have a tubular system where renettes form a large canal leading to an excretory pore.

Reproductive Characteristics

Most nematodes are dioecious, with gonads located freely in the pseudocoelom.
Sperm transfer during copulation is aided by a bursa at the posterior end.
Internal fertilization is the norm, with some species exhibiting ovoviviparity (larval birth).
Nematodes typically undergo four larval molts during development.

Parasitic Adaptations

Parasitic nematodes display high reproductive potential and complex life cycles enhancing host transmission.
Adaptations include enzyme-resistant cuticles, resistant eggs, and encysted larvae for survival.

Human Parasites

Five significant human nematode parasites include:
- Ascaris lumbricoides (Giant Intestinal Roundworm)
- Enterobius vermicularis (Human Pinworm)
- Necator americanus (New World Hookworm)
- Trichinella spiralis (Porkworm)
- Wuchereria spp. (Filarial Worms), which causes elephantiasis.

Evolutionary Background

Nematodes belong to the supergroup Ecdysozoa, characterized by molting exoskeletons.

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Description

Test your knowledge on Phylum Nematoda with these flashcards. Explore key characteristics, dietary habits, and structural features of nematodes. Perfect for biology students studying roundworms.