Protostomes Flashcards
What phylums come under Lophotrochozoans?
Flatworms (Platyhelminthes)
Segmented worms (Annelida)
Molluscs (Mollusca)
What are the main features of Platyhelminthes?
Simple body plan (no body cavity and mouth = anus)
Mesoderm with digestive and reproductive organs
No circulatory organs
Simple brain
Sensory/motor development and muscles allow active lifestyle
What are some features free living marine flatworms?
Predators or scavengers
Gastrovascular cavity with complex folding
Primitive ganglia and eyespots to process stimuli
Regenerate or reproduce sexually as hermaphrodites
How do parasitic flukes reproduce?
Primary host usually a vertebrate
Undergo sexual reproduction in the primary host
Leave through faeces as eggs and develop into ciliated larvae in the water
Invade a secondary host (usually invertebrate)
Reproduce asexually in the secondary host
Leave secondary host into the water and repeat the cycle
What are the main features of the phylum Annelida?
Body is linear and segmented
Body cavity is divided by septa
Circular and longitudinal muscles in the body wall
Digestive tract has specialised regions
Simple brain
What are earthworms important for?
Soil formation
Soil aeration
Releasing nutrients for plants
What are the main features of polychaete worms?
Marine segmented worms
Developed head and feet
What are the main features of the phylum Mollusca?
Not segmented
Diverse but all share the same body plan
Have a visceral mass that contains all the internal organs
Some have a radula to scrape up food from the environment
What animals come under the sub-group gastropods?
Snails
Slugs
Limpets
What animals come under the sub-group bivalves?
Oysters
Mussels
Clams
What animals come under the sub-group cephalopods?
Squid
Octopus
What are some features of cephalopods?
Closed circulatory system
3 hearts
Efficient eye - has no blind spots
Chromatophores for signalling and camouflage
Well developed brain
What phyla come under Ecysozoans?
Roundworms - Phylum Nematoda
Arthropods
What are some features of the phylum Nematoda?
Cuticle is shed
Unsegmented and tapers as tail
Complete digestive tract with anus
Moves by thrashing tail - uses longitudinal muscles (no circular so can’t undergo directional movement)
May be the most abundant multicellular animal
