Phylum Annelida

Question 1

annelida basics

Answer 1

-	“bristle worms”
o	Setae
-	15000+ species 
o	Marine, freshwater, damp terrestrial 
-	Free living, symbiotic, parasitic 
o	Deposit feeders, predators, suspension feeders 
-	Closed circulatory system 
o	Blood never leaves vessels 
o	(in an open heart pumps blood and it pools over organs and into another vessel)
-	centralized nervous system

Question 2

setae

Answer 2

o	Made from epidermis 
o	Helps anchor in tube 
o	For locomotion → paddle
o	Not in leeches  
o	Chintinous, epidermal bristles

Question 3

parapodia

Answer 3

o Paddle like feet
o Respiration, swimming, crawling
o Not in oligochaetes and hirudinideans
o Believed that it was secondarily lost in certain species

Question 4

basic body plan

Answer 4

• Two part head
  o Protomium and peristomium
• Numerous segments/metameres
• Terminal pygidium – new segments (form from butt)
• Epidermis covered in non-chininous cuticle

Question 5

errantia

Answer 5

• Motile polychaetes (many long hairs)
• Well developed sense organs and cephalization
• External fertilization with trochophore larvae
  o Free swimming larvae settles to become baby polychaetes

Question 6

sedentaria

Answer 6

• Contains the former
  o Burrowing and tube dwelling polychaetes
  o Oligochaetes and hirudinians (earthworms and leeches)
  o Head modified for filter or particle feeding
  • Or reduced heads for deposit feeding (earthworms, lugworms)

Question 7

sedentaria polychates

Answer 7

• Cilia and mucus and food grooves on tentacles to capture food
• Reduced parapodia – respiration or separate gills
• Reduced setae – anchor into burrows and tubes
• Tube dwellers, calcareous, mucus, sand grains

Question 8

sedentaria: siboglinidae

Answer 8

• Used to be in its own phyla
• Beard worms discovered in 20th century
  o ~150 deep sea species often in unique ecosystems
• Chitinous tubes
• No mouth or digestive system
  o Direct absorption and feed off what chemoautotrophic bacteria makes for them using H2S

Question 9

sedentaria: echiuridae

Answer 9

• Spoon worms: has a thing like a spoon to gather food on the sea floor
• Not segmented but ancestor was → secondarily lost
• Homologous annelid setae to anchor in tube

Question 10

sedentaria: clitellata

Answer 10

• Formerly classes oligochaeta and hirudinida
• Synapomorphy: clitellum (for reproduction)
• No parapodia
• Have setae
• Found in freshwater and terrestrial environments → no free swimming larvae → direct development (no trochophore)

Question 11

oligochaetes

Answer 11

• 3000 species
• Freshwater, marine, terrestrial
• Earthworms
• Well developed circulatory system → transverse heart
• True segmentation
• Well developed circulatory, digestive and excretory systems – nephridia
  o Organ level
  o Digestive system – intestine that ends in terminal anus
• Fertilizes soil
• Good for fishing
• Ecologically important
• Simultaneous hermaphrodites
  o Both give sperm, fertilize eggs, are the moms
  o In clitellum → insert eggs (that are near head) into mucus ball

Question 12

hiruninae

Answer 12

• Leeches
• 500 species
• Dorsoventrally flattened
• Fixed number of segments
• No setae – secondarily lost
• Clitella but only visible during reproduction
• Posterior and anterior blood suckets
• No septa → solid connective tissue so they can expand and contract
• Blood sucking parasites or carnivores – powerful pharynx

Question 13

medicinal leech

Answer 13

• Hirudo medicinalis
• Blood letting → cure for many things for many years, just bleeding out
• Doesn’t transmit human diseases
• Feed slowly → blood clots quick because hirudin anticoagulant
• Helps reduce swelling

Question 14

carnivorous leech

Answer 14

• Kinabalu giant red leech

- Swallows prey whole

Question 15

phylum spinicula

Answer 15

• Peanut worms
• ~250 species
• Not segmented, no setae
• Ciliated introverted feeding tentacles
• Trochophore learve unites with the greater lophotrochozoans
• Half like molluscs, half like worms