Zoology Unit 2: Platyhelminthes, Nematoda, Annelida, and Mollusca

Comprehensive vocabulary terms and definitions covering Phylum Platyhelminthes, Nematoda, Annelida, and Mollusca based on the lecture notes.

Platyhelminthes Feeding

Flatworms utilize a gastrovascular cavity and pharynx for feeding; they can be free-living or parasitic.

Flame cells

Specialized cells in Platyhelminthes used for the process of excretion.

Auricles

Specialized response organs in Platyhelminthes, often located near eyespots.

Neural ganglion

A simple nervous system component consisting of a group of nerve cells; in roundworms, this ring surrounds the pharynx.

Bilateral symmetry

An important evolutionary development in Platyhelminthes where the body can be divided into identical right and left halves.

Nematos

A Greek word meaning "thread."

Eidos

A Greek word meaning "form of."

Pseudocoelom

A "false coelom," which is a body cavity that is not lined with mesoderm.

Nematoda Digestive System

A complete digestive track that features two openings: a mouth and an anus.

Chemosensors

Specialized sensors in nematodes that help them detect food and environmental stimuli.

Trichinosis

A parasitic disease caused by Genus Trichinella, often contracted by eating undercooked pork or wild game.

Ascariasis

A parasitic disease caused by ingesting ascarid eggs from contaminated soil or feces, which may cause intestinal blockage or lung migration.

Elephantiasis

A condition caused by filarial worms (Superfamily Filarioidea) transmitted by mosquitoes; results in edema (swelling) due to worms blocking the lymphatic system.

Annelida

A phylum of segmented worms whose name means "little ring."

Nephridia

Excretory organs in annelids and mollusks that eliminate metabolic (cellular) waste.

Statocysts

Sense organs in marine annelids used to detect gravity.

Parapodia

Paired appendages in marine annelids used for swimming and crawling.

Clitellum

A specialized structure in earthworms that releases eggs and sperm and later protects developing annelids.

Polychaeta

A class of marine annelids whose name means "many hair/bristles."

Hirudinea

A class of annelids commonly known as leeches, characterized by external parasitism and powerful suckers.

Oligochaeta

A class of annelids including earthworms; the name means "few bristles."

Molluscus

A Latin word meaning "soft."

Mantle

A part of the mollusk body plan that covers the body like a cloak and secretes the shell.

Visceral mass

The section of a mollusk body that contains a group of internal organs.

Radula

A structure with tiny teeth used for feeding, found in Class Gastropoda.

Siphon

A tube-like structure used by Class Bivalvia for filter feeding.

Jet propulsion

A movement method used by cephalopods involving sucking water into the body and expelling it.