Nematoda

These flashcards define key terms related to Nematoda and Ecdysozoa, including processes like molting and concepts such as pseudocoelomates and parasitic worms.

Nematoda

A phylum of roundworms, which includes both free-living and parasitic species.

Ecdysozoa

A clade characterized by molting, including phyla such as Nematoda and Arthropoda.

Molt

The process of shedding an outer layer or cuticle to allow for growth.

Pseudocoelomate

An organism possessing a pseudocoelom, a fluid-filled cavity between tissues.

Reproduction

• Male Nematodes:

  • Produce and deliver sperm using spicules and the gubernaculum.

  • Their reproductive organs include testes, vas deferens, seminal vesicle, and ejaculatory duct.

  Female Nematodes:

  • Produce, fertilize, and lay eggs.

  • Their reproductive organs include ovaries, oviducts, uterus, vagina, and vulva.

  • Fertilization occurs internally, and the female lays fertilized eggs.

Ecdysis

The process of shedding the cuticle or exoskeleton; also known as molting.

Ascaris lumbricoides

Commonly known as the human intestinal roundworm, it is one of the most prevalent parasites.

Pinworm

A small parasitic worm (Enterobius vermicularis) that primarily infects the human large intestine.

Dioecious

Referring to species that have distinct male and female individuals.

Trichinosis

A disease caused by eating raw or undercooked meat infected with larvae of the Trichinella worm.

Hydrostatic skeleton

A fluid-filled cavity that provides support and shape to an organism.

Cuticle

An external, non-living layer secreted by the epidermis; primarily composed of collagen.

Cephalization

The developmental trend whereby sensory organs and nervous tissue become concentrated at the anterior end.(Eyes are located at the front of the person)

Eutelic growth

A type of growth characterized by an increase in individual cell size rather than an increase in cell number.

Lateral expansion

The ability to increase in width; limited in nematodes due to thick cuticle.

Chemosensory sensillae

Sensory structures that detect chemical stimuli; typically found around the mouth of nematodes.

Hydrostatic pressure

The pressure exerted by a fluid in a confined space; important for movement in pseudocoelomates.

Ascaris (lifecycle)

Refers to the specific stages through which the Ascaris worms develop and reproduce, often involving various hosts.

Elephantiasis

A condition characterized by severe swelling, commonly caused by filarial worms transmitted through mosquitoes.

Filariasis

A disease caused by parasitic filarial worms, which can lead to severe swelling and disability.

Trochophore larva

A type of larval form common in some animal groups, which is absent in Ecdysozoa.

Free-living

Organisms that exist independently without depending on a host for nutrients.

Life cycle of common parisitic nematodes

Life cycles can involve 1 or more hosts • Some can be passed directly between humans• Different life stages often look similar (larval worms similar toadults but smaller, may be found in different host or location than adult)

Synapomorphy

distinct pattern of three rings of chemosensory sensillae around mouth (microscopic)

Exrection

by diffusion + specialized gland cells (no protonephridia)(Yes Excetory duct)

Elephantitasis/Filariasis

tropical parasitic disease caused by infection with filarial worms, The infection is transmitted through the bite of infected mosquitoes, and over time, it causes severe swelling and enlargement of body parts, usually the legs, arms, breasts, or genitals.

Circulatory system

No true circulatory system (no heart, blood, or blood vessels). The pseudocoelom (a fluid-filled cavity) acts as a hydrostatic skeleton and allows the distribution of nutrients, waste, and other substances throughout the body.

Respiratory system

No true respiratory system (no lungs, gills, or specialized respiratory organs). Gas exchange occurs through simple diffusion across the body surface.

Life cycle(Start-finish)

Eggs are ingested and juvenile stages develop in the duodenum. Adults reside in the large intestine, where females migrate out of the anus to deposit eggs, causing itching and spreading through contamination.