molluscs Flashcards
molluscs are protostomes. describe protostomes
first embryotic opening is the mouth
what kind of coelomate (body cavity lined by mesoderm cells) are molluscs?
shizocoelomate / coelomate: coelom formed by splitting of mesoderm
what kind of digestive system do molluscs have?
complete digestive system (one way)
what kind of symmetry
bilateral
what level of organization?
Organ level
what layers do molluscs have?
endo, meso, ecto derm
what three main parts are a molluscs body composed of and describe them
- visceral mass: soft bodied portion with internal organs
- foot: muscular portion for locomotion
- mantle: membranous/muscular covering envelops visceral mass. may secrete a shell
molluscs may have a head region with…
- eyes
- other sense organs
what contributes to the molluscs diversity and how can they be distinguished?
- division of body parts
- modification of the foot
what is the radula?
toothy, raspy tongue-like structure
gastropods are _____ footed. describe their feet and how they move
- stomach-footed
- foot is ventrally flattened
- moves by muscle contractions that pass along the foot
cephalopods are ________ footed. describe their physical characteristics
head footed
- tentacles
- beak and radula to tear prey
- cephalization
- eyes similar to vertebraes: lens, retina with photoreceptors
cephalopods brain was formed from a fusion of _____
ganglia (groups of nerves/brain cells)
what do large pairs of nerves in cephalopods contol?
rapid contraction of the mantle
rapid contraction of the mantle in cephalopods allows for what kind of movement?
quick movement by a jet propulsion of water
