Class Scaphopoda – Tusk Shells
Class – Gastropoda
Class Gastropoda –
Class – Sea Hare
Class Bivalvia
Class - Cephalopoda
Characteristics of Molluscans
1. Size – Millimeter to 60 Feet (18M)
2. Major Food source
3. Lifestyle
Simple - Limpets
Complex – Squid and Octopi
Molluscan Body Plan
Circulatory System
n Open Circulatory System
v Means that not all the blood is contained in vessels but rather vessels AND open chambers called sinuses
v Sinuses take place of the Capillaries
v 3 chambered heart
Body Systems
n Respiration – this is accomplished thru the circulation of oxygen-rich water by the MANTLE
n Excretion – this is accomplished by Kidneys that double as a passageway for eggs or sperm
n Nervous System – varies with species. Limpets and Bivalves are simple, Cephalopods are well developed.
Comparison of Body Plans
Specialized Structures
n Radula – Horny-toothed structure found within the pharynx
Used for “Rasping” or “Scraping” plant or animal tissue
Bivalves are filter feeders and have lost this structure
Cephalopods, in addition, have a “Beak” which work together to kill prey
n Operculum – A protective plate that covered the opening to the shell of some gastropods
n Siphon – A tube that allows for water to enter/leave the body of a Mollusc. Bivalves and Cephalopods
n Siphuncle – a cord of tissue that connects all the chambers of the Nautilus and used for boyancy
n Nacre – secretion around sand particles by oysters resulting in a pearl.
n Hectocotylus – a special structure on one of the arms of an Octopus (male) that allows it to deposit sperm packets into the females mantle cavity
Tidak ada komentar:
Posting Komentar