Phylum Annelida

Question 1

Characteristics of Errantids and Sedenterids

Answer 1

Errantid: Motile and active, well-developed parapodia supported by chitinous aciculae, head appendages for sensory purposes, cephalic eyes and chemosensory organs, reversible armed pharynx
Sedentarids: sessile and buried or live within tubes, reduced parapodia and no aciculae, head appendages and cephalic eyes generally lacking, any head appendages are used for feeding, normally no reversible pharynx and if it is not armed

Question 2

Nereis Locomotion

Answer 2

The parapodia can function on their own to produce slow or crawling locomotion
Longitudinal muscles may also be employed for lateral undulation for fast swimming locomotion paired with parapodia movement
If these worms attempt to burrow they will also activate their circular muscles to push them through the substrate

Question 3

Earthworm locomotion

Answer 3

Using the setae to anchor into the earth, they then contract circular muscles near the anterior end to push their head forward and anchor there. A wave of circular muscle moves posteriorly creating fat and thin sections
A wave of longitudinal muscles then follows elongating the worms and effectively moving them forward
This is called peristaltic crawling

Question 4

Nereididae feeding

Answer 4

The armed eversible pharynx is used to capture and subdue prey as well as tear off chunks of algae and decaying matter

Question 5

Glyceridae feeding

Answer 5

Everted their well-armed (4 jawed pharynx) to subdue prey

Often these jaws have venom associated with them

Question 6

Arenicolidae feeding

Answer 6

They live in j-shaped burrows and draw in water that contains bacteria, using their sticky pharynx they deposit feed

Question 7

Sabellidae feeding

Answer 7

They capture food particles floating in the water columns using their tentacled crown

Question 8

Terebellidae feeding

Answer 8

They run their tentacles over the sediments and ingest the food particles as well as sediments

Question 9

Siboglinidae feeding

Answer 9

They diffuse sulphides and CO2/O2 into their body via their head appendage (branchial filaments) and sulfur fixing bacteria living within their trophosome create energy from it

Question 10

Locomotion and feeding adaptations of leeches

Answer 10

Flattened body plan, oral and posterior sucker, well-developed metanephridia for osmoregulation, folded gut wall for increase SA, thickened cuticles for penetration
Use of both suckers for a movement called looping for sinusoidal wave swimming