Protostomes 2

Flashcards covering the classification, characteristics, and biology of Platyhelminthes and Molluscs, based on lecture notes from Dr. Katy Williams' B+E 2024 lecture.

Platyhelminthes

Phylum of flatworms with soft, flat, and unsegmented bodies. Includes free-living and parasitic forms found in marine, freshwater, and terrestrial habitats.

Acoelomate

Lacking a fluid-filled cavity between the body wall and digestive track, a characteristic of Platyhelminthes.

Protonephridia

Excretory system in Platyhelminthes, featuring flame cells for waste removal.

Cephalisation

Concentration of sense organs and nerve tissue in the anterior end of Platyhelminthes.

Hermaphroditic

Having both male and female reproductive organs, common in Platyhelminthes.

Turbellaria

Class of free-living, mostly carnivorous Platyhelminthes, such as planarians.

Cestoda

Class of parasitic Platyhelminthes, including tapeworms, which require at least two hosts in their life cycle.

Trematoda

Class of parasitic Platyhelminthes, including flukes, which may involve several hosts in their life cycle and have two suckers.

Monogenea

Class of parasitic Platyhelminthes that infect a single host, often fish.

Mollusca

Phylum of molluscs characterized by a body plan with three main components: foot, visceral mass, and mantle.

Foot (Mollusca)

Large, muscular structure in molluscs, originally for locomotion.

Visceral Mass (Mollusca)

Contains the heart, digestive, excretory, and reproductive organs in molluscs.

Mantle (Mollusca)

Fold of tissue that covers organs in the visceral mass of molluscs and secretes the calcareous shell.

Radula

Rasping structure in molluscs used for scraping algae from rocks or feeding.

Open Circulatory System

Blood and fluids empty into the hemocoel, where oxygen is delivered to internal organs. Blood eventually re-enters blood vessels and is pumped by a heart

Aplacophora

Class of molluscs mainly found in deep water; they are small and worm-shaped and carry calcareous spines.

Polyplacophora

Class of molluscs with eight dorsal shell plates, mainly intertidal grazers on algae using a radula.

Monoplacophora

Class of molluscs that were most abundant during the Cambrian, with only a few species surviving in deep water.

Scaphopoda

Class of molluscs (tusk shells) with a tubular tapering shell and no gills, eyes, or heart; they use club-like retractile tentacles in prey capture.

Gastropoda

Class of molluscs including snails, slugs, nudibranchs, limpets, and abalones; most move by gliding on the foot and typically have a spiral shell.

Bivalvia

Class of molluscs including freshwater or marine organisms with a hinged shell and two valves; they filter feed with ciliated gills.

Cephalopoda

Class of molluscs including squids, octopuses, and nautiluses; they move by jet propulsion using a modified excurrent siphon.