fossils 2.2

Flashcards covering key vocabulary and concepts from the lecture on Bivalve and Gastropod Molluscs.

Phylum Mollusca

The second most diverse animal phylum, characterized by calcareous shells.

Mollusc shells

Generally made of aragonite, these shells can be single or multiple, and may be chambered.

Radula

A feeding organ made from chitin, found only in molluscs.

Class Gastropoda

Comprises 75% of all molluscs; features include a single coiled shell (or none) and a distinct head.

Bivalvia

Class of molluscs with two valves joined by a ligament, no head, no radula, and enlarged gills.

Umbo

The oldest part of the bivalve shell.

Infaunal bivalves

Bivalves that live buried in sediment.

Epifaunal bivalves

Bivalves that live on the sediment, which may be free-lying, attached, or cemented.

Pelagic

Refers to organisms that live in the water column; includes planktonic (passively floating) and nektonic (actively swimming) modes.

Benthic

Refers to organisms that live on or in the sediment, including infaunal, epifaunal, sessile, and vagrant forms.

Suspension (filter) feeding

A feeding strategy in which organisms filter food particles from the water.

Dentition

Teeth and sockets in bivalves that facilitate the closing of the shell valves.

Pallial line

Marks the line of mantle attachment in the bivalve shell.

Byssal threads

Fibrous structures that some bivalves use to attach themselves to substrates.

Siphon

An organ in bivalves used for inhaling and exhaling water.