6.1 Introduction
6.2 Maintaining Salt and Water Balance
6.2.1 Osmosis and the Movement of Molecules across Cell Membranes
6.2.2 Salinity and Its Importance in Aquatic Habitats
6.2.2.1 Cell Volume Regulation
6.2.2.2 Hormonal Control of Osmoregulation
6.2.2.3 Marine Environment
6.2.2.4 Upper Littoral and Supralittoral Environment
6.2.2.5 Estuarine Environment
6.2.2.6 Hypersaline and Hydrothermal Environments
6.2.2.7 Fresh-Water Environments
6.2.3 The Terrestrial Environment
6.2.3.1 Amphibious Molluscs
6.3 The Vascular System
6.3.1 Overview of the Cardiovascular System and Circulation Patterns
6.3.2 Heart Structure and Function
6.3.2.1 Heart Musculature
6.3.2.2 Heart Regulation and Control
6.3.2.3 Heart Metabolism
6.3.2.4 Heart Performance
6.3.3 The Branchial Hearts of Cephalopods
6.3.4 The Aortic System and Aortic Bulb
6.3.4.1 Blood Flow through the Arteries
6.3.4.2 Arterial Haemocoels
6.3.5 Exchange Vessels – Capillaries
6.3.6 The Venous System and Haemocoelic Spaces
6.3.7 Blood Flow to the Respiratory Surface(s) and Kidney(s)
6.3.8 Compensation Mechanisms
6.3.9 Blood Release Mechanisms and the Addition of Seawater
6.3.10 Comparison of Vertebrate and Coleoid Cephalopod Vascular Systems
6.4 Molluscan Blood
6.4.1 Respiratory Pigments
6.4.1.1 Haemocyanin
6.4.1.2 The Globins: Myoglobin and Haemoglobin
6.4.2 Haemocytes
6.4.2.1 Erythrocytes
6.4.2.2 Immune Response and Other Functions
6.5 Pore Cells (Rhogocytes)
6.6 The Excretory System
6.6.1 Filtration
6.6.2 Podocytes 306
6.6.3 The Nephridial Gland
6.6.4 Excretory Challenges
6.6.4.1 Estuarine, Fresh-Water, Supralittoral, and Terrestrial Molluscs
6.6.4.2 Nitrogen Metabolism
6.6.5 Heavy Metal Uptake and Excretion/Detoxification
6.6.6 Excretion via the Digestive Gland
6.7 Comparative Kidney Morphology, the Site of Filtration and Excretion
6.7.1 Aplacophorans
6.7.2 Polyplacophora
6.7.3 Monoplacophora
6.7.4 Bivalvia
6.7.4.1 Estuarine and Fresh-Water Bivalves
6.7.5 Scaphopoda
6.7.6 Cephalopoda
6.7.6.1 Nautiloid Pericardial Appendages and Their Symbiotic Bacteria
6.7.6.2 The Branchial Heart Appendages in Coleoids
6.7.6.3 The Renal Appendages in the ‘Kidneys’
6.7.6.4 The Digestive Gland Duct Appendages (‘Pancreas’) of Coleoids
6.7.6.5 Utilisation of Ammonia for Buoyancy in Cephalopods
6.7.7 Gastropoda
6.7.7.1 Patellogastropoda
6.7.7.2 Vetigastropoda
6.7.7.3 Neritimorpha
6.7.7.4 Caenogastropoda
6.7.7.5 Heterobranchia