phylum mollusca!!
DESCRIPTION
Phylum Mollusca!!. Created by: Mariah Ghant , Saori Ishizuka, and Monica Lin. Germ Layers. 3 germ layers Ectoderm Mesoderm Endoderm. Symmetry. Bilateral. Coelom. Mollusca are true c oelom Fluid filled cavity within the mesoderm. Digestive Tract. Extracellular digestion - PowerPoint PPT PresentationTRANSCRIPT
Phylum Mollusca!!Created by: Mariah Ghant, Saori Ishizuka, and Monica Lin
Germ Layers• 3 germ layers• Ectoderm• Mesoderm• Endoderm
Symmetry• Bilateral
Coelom• Mollusca are true coelom• Fluid filled cavity within the mesoderm
Digestive Tract• Extracellular digestion • Complete digestive tract• Mouth• Anus
Cephalization• Evident in mollusca• Cephalopods have eyes with image formation
• Neurons concentrate in a ganglial pattern
Segmentation• No segmentation• Instead, body divided into head, foot and visceral
mass
Skeleton & Appendages• Mollusca have soft bodies • Often protected by a shell• Some have lost their shells because of evolution
• Muscular tube feet • Skeleton• Shell with three layers: periostracum, prismatic layer,
nacreous layer
Circulatory System• Open circulatory system• Except for Cephalopods, blood does not circulate within
the vessels• Collected from the gills• pumped through the heart• released directly into spaces in the tissues from which
it returns to the gills and then to the heart• Closed circulatory system for cephalopods
Respiratory System• Gills in aquatic forms• Discrete respiratory system • Improved capacity for oxygen uptake and distribution• Increases body mass
Reproduction• Single or double set of gonads and ducts in each
sex• Bivalves and some snails of mollusca are
hermaphrodites
Habitat• Occur in almost every habitat found on Earth• Most are found in marine environments, extending
from the intertidal to the deepest oceans