Mollusks Phylum Mollusca Advanced Invertebrates Phylum Mollusca Characteristics

Mollusks Phylum Mollusca

Advanced Invertebrates • Phylum Mollusca Characteristics – 1. Visceral Mass: soft bodied portion containing internal organs – 2. Foot: Strong muscular part used for locomotion – 3. Mantle: Covering enveloping the visceral mass • Over 112, 000 different species

Class Gastropoda • • “Belly Foot” Snails Slugs Conches

Class Cephalopoda • “Head Foot” • Octopus • Squid

Class Bivalvia • Clams • Oysters • Scallops

Classification • • • Common Name: Clam Scientific Name: Unio, Anodonta Phylum: Mollusca Class: Bivalvia Other: Class Pelecypoda “Hatchet Foot”

Major Characteristics • Body Plan: Foot, Mantle, Visceral Mass • Body Cavity: Visceral Mass contains all internal organs • Symmetry: Bilateral • Cell Specialization: Complex Organs, “Soft Bodied”

Life Support Processes • Absorption: Intestines, Nephridia • Feeding: Filter Feeder, Gills, Radula = flexible, tongue-like projection with teeth • Digestion: Stomach, Intestines • Respiration: Gills • Circulation: Open System - Blood travels through sinuses, flows into pericardial cavity around heart, blood pigment is blue Hemocyanin

Life Support Processes • Excretion: Anus = solids, Nephridia = remove liquid ammonia waste • Secretion: The mantle secretes the shell • Response: Ganglia, Ocelli (Primitive Eyespot), Statocysts = Balance • Movement: Foot = burrow into ocean floor, Adductor Muscles = Opens shell when relaxed

Life Support Processes • Reproduction: Separate sexes, Trochophore = larvae • Support: Shell provides all protection

Ecological Relationships • Sessile • Pearl Formation = due to secretion of mantle • Food for starfish

Body Systems Compared With Humans • Digestive System • Separate sexes • Gonads

Advancements Over Previous Phylum • Heart • Gills • Shell

• The largest bivalve is the Marine Giant Clam that can reach a size of 50 in. in length and can weigh over 750 lbs. ! • The slowest growing animal of any kind is a deep sea clam which only grows. 31 in every 100 years!

• The largest known invertebrate is the Giant Squid Architeuthis dux. They can be over 60 ft. in length and weigh more than 4, 000 lbs. ! • The largest eye in the animal kingdom belongs to the Giant Squid; over 16 in. in diameter! (About the size of a hubcap)