Phylum Nematoda Lecture Notes

Vocabulary-style flashcards covering the anatomy, physiology, reproduction, and specific examples of the Phylum Nematoda based on the June 25 lecture.

Phylum Nematoda

A phylum of bilaterally symmetrical organisms possessing a pseudocoel, often dioecious with sexual dimorphism, and ranging from less than $1\,mm$ to over $10\,meters$ in length.

Pseudocoel

A fluid-filled cavity enclosed by the body wall that differs from a true coelom because it has no peritoneal (mesodermal) lining.

Cuticle

A noncellular, chitinous layer secreted by the underlying hypodermis that is shed 4 times (4 molts) during ontogeny.

Hypodermis

An underlying layer of the body wall that secretes the cuticle; it is syncitial in adult worms with nuclei located in 4 epidermal cords.

Epidermal cords

Longitudinal structures that divide the nematode body into 4 quadrants; dorsal and ventral cords contain nerve trunks, while lateral cords contain excretory canals.

Myocyton

The noncontractile cell body of a nematode muscle cell, which also contains a contractile portion using myosin and actin.

Hydrostatic skeleton

A structural system composed of the cuticle, hypodermis, somatic musculature, and fluid-filled pseudocoel that depends on an enclosed volume of non-compressible fluid.

Hemolymph

The specific term for the fluid found within the pseudocoel of a nematode.

Sensilla

Small sense organs found in nematodes, which are most prominent in the cephalic and cauda regions.

Depressor ani

The anal dilator muscles that contract to open the anus, allowing hydrostatic pressure to cause defecation.

Rachis

The structure through which germ cells move within the solid cord gonads of a nematode.

Pseudopodium

The means of locomotion used by nematode spermatozoa.

Copulatory spicules

Structures found in male nematodes used specifically during the process of copulation.

Trichuris trichiura

Commonly known as whipworm, this tissue parasite embeds its slender anterior end into gut mucosa and can live for several years.

Embryonation

The development period for Trichuris trichiura eggs, which takes 21 days in moist and shady soil.